TheInfoList

Medical ultrasound includes
diagnostic Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different academic discipline, disciplines, with variations in the use of logic, analytics, and experience, to determine "causality, cause an ...
techniques (mainly
imaging Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of an image). Imaging technology is the application of materials and methods to create, preserve, or duplicate images. I ...
techniques) using
ultrasound Ultrasound is s with higher than the upper audible limit of human . Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is appro ...

, as well as
therapeutic A therapy or medical treatment (often abbreviated tx, Tx, or Tx) is the attempted remediation of a health Health is a state of physical, mental and social well-being Well-being, also known as ''wellness'', ''prudential value'' or ''quality ...
applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as
tendons A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle Muscle is a soft tissue found in most animals. Muscle cells contain protein Proteins are large biomolecules or macromole ...
,
muscles Skeletal muscles (commonly referred to as muscles) are Organ (biology), organs of the vertebrate muscular system that are mostly attached by tendons to bones of the skeleton. The muscle cells of skeletal muscles are much longer than in the other ...

, joints, blood vessels, and internal organs, to measure some characteristics (e.g. distances and velocities) or to generate an informative audible sound. Its aim is usually to find a source of disease or to exclude
pathology Pathology is the study of the causesCauses, or causality, is the relationship between one event and another. It may also refer to: * Causes (band), an indie band based in the Netherlands * Causes (company), an online company See also * Cau ...
. The usage of ultrasound to produce visual images for medicine is called medical ultrasonography or simply sonography. The practice of examining
pregnant Pregnancy, also known as gestation, is the time during which one or more offspring develops inside a woman. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercour ...

women using ultrasound is called
obstetric ultrasonography ultrasonography, or prenatal ultrasound, is the use of in , in which sound waves are used to create real-time visual images of the developing or in the (womb). The procedure is a standard part of care in many countries, as it can provide a v ...
, and was an early development of clinical ultrasonography. Ultrasound is composed of
sound wave In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, its Motion (physics), motion and behavior throug ...

s with
frequencies Frequency is the number of occurrences of a repeating event per unit of time A unit of time is any particular time Time is the indefinite continued sequence, progress of existence and event (philosophy), events that occur in an apparent ...

which are significantly higher than the range of human hearing (>20,000 Hz). Ultrasonic images, also known as sonograms, are created by sending pulses of ultrasound into
tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa dubitata'', a species of geometer mot ...
using a probe. The ultrasound off tissues with different reflection properties and are returned to the probe which records and displays them as an image. Many different types of images can be formed. The most common is a B-mode image (Brightness), which displays the
acoustic impedance Acoustic impedance and specific acoustic impedance are measures of the opposition that a system presents to the acoustic flow resulting from an acoustic pressure applied to the system. The SI unit The International System of Units, known b ...
of a two-dimensional cross-section of tissue. Other types display
blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory system is controlled by homeostasis, homeostatic mechanisms of autoregulation, just as hydraul ...
, motion of tissue over time, the location of blood, the presence of specific molecules, the stiffness of tissue, or the anatomy of a three-dimensional region. Compared to other medical imaging modalities, ultrasound has several advantages. It provides images in real-time, is
portable Portable may refer to: General * Portable building, a manufactured structure that is built off site and moved in upon completion of site and utility work * Portable classroom, a temporary building installed on the grounds of a school to provide ad ...
, and can consequently be brought to the bedside. It is substantially lower in cost than other imaging strategies and does not use harmful
ionizing radiation Ionizing radiation (or ionising radiation), including nuclear radiation, consists of s or s that have sufficient to s or s by detaching s from them. The particles generally travel at a speed that is greater than 1% of , and the electromagnetic w ...
. Drawbacks include various limits on its field of view, the need for patient cooperation, dependence on patient physique, difficulty imaging structures obscured by
bone A bone is a rigid tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa dubit ...

, air or gases,It is for this reason that the person subjected to ultrasound of organs that can contain quantities of air or gas, such as the stomach, intestine and bladder, must follow a food preparation designed to reduce their quantity: specific diet and supplements for the intestine and intake of non-carbonated water to fill the bladder; sometimes, during the examination, it may be required to fill the stomach with non-carbonated water. and the necessity of a skilled operator, usually with professional training. Sonography (ultrasonography) is widely used in
medicine Medicine is the science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity, awareness, or understanding of someone or something, such as facts ( descriptive knowledge), skills (proced ...

. It is possible to perform both
diagnosis Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different academic discipline, disciplines, with variations in the use of logic, analytics, and experience, to determine "causality, cause an ...
and therapeutic procedures, using
ultrasound Ultrasound is s with higher than the upper audible limit of human . Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is appro ...

to guide interventional procedures such as
biopsies A biopsy is a medical test A medical test is a medical procedure performed to detect, diagnose, or monitor diseases, disease processes, susceptibility, or to determine a course of treatment. Medical tests such as, physical and visual exams, ...

or to drain collections of fluid, which can be both diagnostic and therapeutic.
Sonographer A sonographer is a healthcare professional who specialises in the use of ultrasonic imaging devices to produce diagnostic images, scans, videos or three-dimensional volumes of anatomy and diagnostic data. The requirements for clinical practice va ...
s are medical professionals who perform scans which are traditionally interpreted by radiologists, physicians who specialize in the application and interpretation of medical imaging modalities, or by cardiologists in the case of cardiac ultrasonography (
echocardiography An echocardiography, echocardiogram, cardiac echo or simply an echo, is an of the . It is a type of of the heart, using standard ultrasound or . Echocardiography has become routinely used in the diagnosis, management, and follow-up of patients ...
). Increasingly, physicians and other healthcare professionals who provide direct patient care are using ultrasound in office and hospital practice (
point-of-care ultrasound Emergency ultrasound or point-of-care ultrasound (POCUS) is the application of ultrasound Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different f ...
). Sonography is effective for imaging soft tissues of the body. Superficial structures such as
muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly cat ...

,
tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant l ...

,
testis Testicle or testis (plural testes) is the male Male (♂) is the sex of an organism that produces the gamete known as sperm. A male gamete can fuse with a larger female gamete, or ovum, in the process of fertilization. A male cannot sexual ...

,
breast The breast is one of two prominences located on the upper ventral Standard anatomical terms of location deal unambiguously with the anatomy of animals, including humans. Terms used generally derive from Latin or Greek language, Greek roots ...

,
thyroid The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobe (anatomy), lobes. The lower two thirds of the lobes are connected by a thin band of Connective tissue, tissue call ...

and parathyroid glands, and the
neonatal 222x222px, Eight-month-old sororal twin sisters An infant (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is the more formal or specialised synonym for the common term ''baby'', meaning the very young offspri ...
brain are imaged at higher
frequencies Frequency is the number of occurrences of a repeating event per unit of time A unit of time is any particular time Time is the indefinite continued sequence, progress of existence and event (philosophy), events that occur in an apparent ...

(7–18 MHz), which provide better linear (axial) and horizontal (lateral)
resolution Resolution(s) may refer to: Common meanings * Resolution (debate), the statement which is debated in policy debate * Resolution (law), a written motion adopted by a deliberative body * New Year's resolution, a commitment that an individual make ...

. Deeper structures such as liver and kidney are imaged at lower frequencies (1–6 MHz) with lower axial and lateral resolution as a price of deeper tissue penetration. A general-purpose ultrasound transducer may be used for most imaging purposes but some situations may require the use of a specialized transducer. Most ultrasound examination is done using a transducer on the surface of the body, but improved visualization is often possible if a transducer can be placed inside the body. For this purpose, special-use transducers, including endovaginal, endorectal, and transesophageal transducers are commonly employed. At the extreme, very small transducers can be mounted on small diameter catheters and placed within blood vessels to image the walls and disease of those vessels.

# Anesthesiology

In
anesthesiology Anesthesiology is the medical speciality, medical specialty concerned with the total perioperative medicine, perioperative care of patients before, during and after surgery. It encompasses anesthesia, intensive care medicine, critical emergency ...
, ultrasound is commonly used to guide the placement of needles when injecting local anaesthetic solutions in the proximity of
nerve A nerve is an enclosed, cable-like bundle of fibers (called axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, spelling differences), is a long, ...

s identified within the ultrasound image (nerve block). It is also used for vascular access such as
cannulation A cannula (; from Latin ''"little reed"''; plural ''cannulae'' or ''cannulas'') is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of samples. In simple terms, a cannula can surround the i ...
of large central veins and for difficult arterial cannulation.
Transcranial Doppler Transcranial Doppler (TCD) and transcranial color Doppler (TCCD) are types of Doppler ultrasonography Doppler ultrasonography is medical ultrasonography Medical ultrasound (also known as diagnostic sonography or ultrasonography) is a medical ...

is frequently used by neuro-anesthesiologists for obtaining information about flow-velocity in the basal cerebral vessels.

# Angiology (vascular)

In
angiology Angiology (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 mill ...
or
vascular The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an Biological system, organ system that permits blood to circulate and transport nutrien ...
medicine,
duplex ultrasound Doppler ultrasonography is medical ultrasonography that employs the Doppler effect to generate medical imaging, imaging of the movement of tissue (biology), tissues and body fluids (usually blood), and their relative velocity to the ultrasound prob ...
(B Mode imaging combined with Doppler flow measurement) is used to diagnose arterial and venous disease. This is particularly important in potential neurologic problems, where
carotid ultrasound In anatomy, the left and right common carotid arteries (carotids) (Entry "carotid"
in
carotid arteries In anatomy, the left and right common carotid arteries (carotids) (Entry "carotid"
in
transcranial Doppler Transcranial Doppler (TCD) and transcranial color Doppler (TCCD) are types of Doppler ultrasonography Doppler ultrasonography is medical ultrasonography Medical ultrasound (also known as diagnostic sonography or ultrasonography) is a medical ...

is used for imaging flow in the intracerebral arteries.
Intravascular ultrasound Intravascular ultrasound (IVUS) is a medical imaging methodology using a specially designed catheter with a miniaturized ultrasound Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing ...
(''IVUS'') uses a specially designed
catheter In medicine Medicine is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organizes knowledge in the form of Testability, testabl ...

with a miniaturized
ultrasound Ultrasound is s with higher than the upper audible limit of human . Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is appro ...

probe attached to its distal end, which is then threaded inside a blood vessel. The proximal end of the
catheter In medicine Medicine is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organizes knowledge in the form of Testability, testabl ...

is attached to computerized
ultrasound Ultrasound is s with higher than the upper audible limit of human . Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is appro ...

equipment and allows the application of
ultrasound Ultrasound is s with higher than the upper audible limit of human . Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is appro ...

technology, such as a
piezoelectric transducer Piezoelectricity is the electric charge Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two types of electric charge: ''positive'' and ''negative'' (comm ...
or capacitive micromachined ultrasonic transducer, to visualize the
endothelium Endothelium is a single layer of squamous Epithelium () is one of the four basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. Wit ...
of
blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to circulate and transport nutrients (such as amino ...
s in living individuals. In the case of the common and potentially, serious problem of blood clots in the deep veins of the leg,
ultrasound Ultrasound is s with higher than the upper audible limit of human . Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is appro ...
plays a key diagnostic role, while ultrasonography of chronic venous insufficiency of the legs focuses on more
superficial vein A superficial vein is a vein Veins are blood vessels The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system An organ ...

s to assist with planning of suitable interventions to relieve symptoms or improve cosmetics.

# Cardiology (heart)

Echocardiography An echocardiography, echocardiogram, cardiac echo or simply an echo, is an ultrasound Ultrasound is s with higher than the upper audible limit of human . Ultrasound is not different from "normal" (audible) sound in its physical properties ...
is an essential tool in
cardiology Cardiology (from Ancient Greek, Greek ''kardiā'', "heart" and ''wikt:-logia, -logia'', "study") is a branch of medicine that deals with the disorders of the heart as well as some parts of the circulatory system. The field includes medical dia ...
, assisting in evaluation of
heart valve A heart valve is a one-way valve check valve Image:Check Valve.svg, 140px, Check valve symbol on piping and instrumentation diagrams. The arrow shows the flow direction. A check valve, non-return valve, reflux valve, retention valve, foot valv ...
function, such as
stenosis A stenosis (from Ancient Greek στενός, "narrow") is an abnormal narrowing in a blood vessel or other tubular Organ (anatomy), organ or structure such as foramina and canals. It is also sometimes called a stricture (as in urethral stricture) ...
or insufficiency, strength of
cardiac muscle Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism ...

contraction, and
hypertrophy __NOTOC__ Hypertrophy (, from Greek ὑπέρ "excess" + τροφή "nourishment") is the increase in the volume of an organ or tissue due to the enlargement of its component Cell (biology), cells. It is distinguished from hyperplasia, in which ...
or dilatation of the main chambers. ( ventricle and atrium)

# Emergency medicine

Point of care Clinical point of care (POC) is the point in time when clinician A clinician is a health care Healthcare is the maintenance or improvement of health Health is a state of physical, mental and social well-being Well-being, also known as '' ...
ultrasound Ultrasound is sound wave In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, ...
has many applications in
emergency medicine #REDIRECT Emergency medicine #REDIRECT Emergency medicine#REDIRECT Emergency medicine Emergency medicine is the medical specialty concerned with the care of illnesses or injury, injuries requiring immediate medical attention. Emergency physician ...

. These include differentiating cardiac from pulmonary causes of , and the Focused Assessment with Sonography for Trauma (FAST) exam, extended to include assessment for significant
hemoperitoneum Hemoperitoneum (also haemoperitoneum, sometimes also hematoperitoneum) is the presence of blood Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrient A nutrient is a substance used by an org ...
trauma Trauma most often refers to: *Major trauma, in physical medicine, severe physical injury caused by an external source *Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event *Traumatic injur ...
( EFAST). Other uses include assisting with differentiating causes of abdominal pain such as
gallstone A gallstone is a stone A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition and the way in which it is formed. Rocks form the Ear ...

s and
kidney stones Kidney stone disease, also known as nephrolithiasis or urolithiasis, is when a solid piece of material (kidney stone) develops in the urinary tract The urinary system, also known as the renal system or urinary tract, consists of the kidneys ...
. Emergency Medicine Residency Programs have a substantial history of promoting the use of bedside ultrasound during physician training.

# Gastroenterology/Colorectal surgery

Both
abdominal The abdomen (colloquially called the belly, tummy, midriff or stomach) is the part of the body between the thorax The thorax or chest is a part of the anatomy of humans, mammals, other tetrapod animals located between the neck and the abdomen. I ...
and
endoanal ultrasound Endoanal ultrasound is a type of medical investigation which images the structures of the anal canal The anal canal is the terminal segment of the large intestine, between the rectum and anus, located below the level of the pelvic diaphragm. It is ...
are frequently used in
gastroenterology Gastroenterology is the branch of medicine Medicine is the science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity, awareness, or understanding of someone or something, such as ...
and
colorectal surgery thumb The thumb is the first digit of the hand A hand is a prehensile, multi- fingered appendage located at the end of the forearm The forearm is the region of the upper limb between the Elbow-joint, elbow and the wrist. The term forearm ...
. In abdominal sonography, the major organs of the abdomen such as the
pancreas The pancreas is an Organ (anatomy), organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdominal cavity, abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine ...

,
aorta The aorta ( ) is the main and largest artery An artery (plural arteries) () is a blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vas ...

,
inferior vena cava The inferior vena cava is a large vein that carries the deoxygenated blood Blood is a body fluid Body fluids, bodily fluids, or biofluids are liquid A liquid is a nearly incompressible In fluid mechanics or more generally conti ...

,
liver The liver is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's t ...

,
gall bladder In vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotrop ...
,
bile duct A bile duct is any of a number of long tube-like structures that carry bile, and is present in most vertebrates. Bile, required for the digestion of food, is secreted by the liver into passages that carry bile toward the hepatic duct, which ...
s,
kidney The kidneys are two reddish-brown bean-shaped organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized ...

s, and
spleen The spleen is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's ...

may be imaged. However, sound waves may be blocked by gas in the
bowel The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system The human digestive system consists of the human gastrointestinal tract, gastrointestinal tract plus the accessory ...
and attenuated to differing degrees by fat, sometimes limiting diagnostic capabilities. The
appendix Appendix may refer to: In documents *Addendum, an addition made to a document by its author after its initial printing or publication *Bibliography, a systematic list of books and other works *Index (publishing), a list of words or phrases with po ...

can sometimes be seen when inflamed (e.g.:
appendicitis Appendicitis is inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a pr ...

) and ultrasound is the initial imaging choice, avoiding radiation if possible, although it frequently needs to be followed by other imaging methods such as CT.
Endoanal ultrasound Endoanal ultrasound is a type of medical investigation which images the structures of the anal canal The anal canal is the terminal segment of the large intestine, between the rectum and anus, located below the level of the pelvic diaphragm. It is ...
is used particularly in the investigation of anorectal symptoms such as
fecal incontinence Fecal incontinence (FI), or in some forms encopresis Encopresis is voluntary or involuntary passage of feces outside of toilet trained contexts (fecal soiling) in children who are four years or older and after an organic cause has been exclude ...

or
obstructed defecation Obstructed defecation is "difficulty in evacuation or emptying the rectum
hich Ij ( fa, ايج, also Romanize Romanization or romanisation, in linguistics Linguistics is the scientific study of language A language is a structured system of communication used by humans, including speech (spoken language), ge ...

may occur even with frequent visits to the toilet and even with passing soft motions". The conditions that can create the symptom are sometimes grouped together as de ...
. It images the immediate
perianal The anus (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Rom ...
anatomy and is able to detect occult defects such as tearing of the anal sphincter.
Ultrasonography of liver tumors Ultrasonography of liver tumors involves two stages: detection and characterization. Tumor detection is based on the performance of the method and should include morphometric information (three axes dimensions, volume) and topographic information ...
allows for both detection and characterization.

# Gynecology and obstetrics

Gynecologic ultrasonography Gynecologic ultrasonography or gynecologic sonography refers to the application of medical ultrasonography Medical ultrasound (also known as diagnostic sonography or ultrasonography) is a medical imaging, diagnostic imaging technique, or thera ...
examines female pelvic organs (specifically the
uterus The uterus (from Latin "uterus", plural ''uteri'') or womb () is the main female hormone-responsive, sex organ, secondary sex organ of the reproductive system in humans and most other mammals. Things occurring in the uterus are described with t ...

,
ovaries The ovary is an organ found in the female reproductive system 300px, 1. Labia_majora.html"_;"title="Vulva: 2. Labia_majora">Vulva: 2. Labia_majora; 3. Labia_minora; 4. Vulval_vestibule.html" "title="Labia_minora.html ...

, and
Fallopian tubes The Fallopian tubes, also known as uterine tubes, salpinges (singular salpinx), or oviducts, are tubes that stretch from the to the , in the human . In other mammals they are called s. A passes through the Fallopian tubes from the ovaries t ...
) as well as the
bladder The urinary bladder, or simply bladder, is a hollow muscular organ in humans and other vertebrates that stores urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ure ...
, adnexa, and Pouch of Douglas. It uses transducers designed for approaches through the lower abdominal wall, curvilinear and sector, and specialty transducers such as endovaginal. Obstetrical sonography was originally developed in the late 1950s and 1960s by Sir Ian Donald and is commonly used during
pregnancy Pregnancy, also known as gestation, is the time during which one or more offspring In biology, offspring are the young creation of living organisms, produced either by a Asexual reproduction, single organism or, in the case of sexual repr ...

to check the development and presentation of the
fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo An embryo is the early stage of development of a multicellular organism A multicellular organism is an organism tha ...

. It can be used to identify many conditions that could be potentially harmful to the mother and/or baby possibly remaining undiagnosed or with delayed diagnosis in the absence of sonography. It is currently believed that the risk of delayed diagnosis is greater than the small risk, if any, associated with undergoing an ultrasound scan. However, its use for non-medical purposes such as fetal "keepsake" videos and photos is discouraged. Obstetric ultrasound is primarily used to: *Date the pregnancy (
gestational age Gestational age is a measure of the age of a pregnancy Pregnancy, also known as gestation, is the time during which one or more offspring In biology, offspring are the young creation of living organisms, produced either by a Asexual repr ...
) *Confirm fetal viability *Determine location of
fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo An embryo is the early stage of development of a multicellular organism A multicellular organism is an organism tha ...

, intrauterine vs *Check the location of the placenta in relation to the cervix *Check for the number of fetuses (
multiple pregnancy A multiple birth is the culmination of one multiple pregnancy Pregnancy, also known as gestation, is the time during which one or more offspring develops inside a woman. A multiple birth, multiple pregnancy involves more than one offspring, ...
) *Check for major physical abnormalities. *Assess fetal growth (for evidence of
intrauterine growth restriction Intrauterine growth restriction (IUGR) refers to poor growth of a fetus while in the mother's womb during pregnancy. The causes can be many, but most often involve poor maternal nutrition or lack of adequate oxygen supply to the fetus. At least ...
( IUGR)) *Check for fetal movement and heartbeat. *Determine the sex of the baby According to the European Committee of Medical Ultrasound Safety (ECMUS)
Ultrasonic examinations should only be performed by competent personnel who are trained and updated in safety matters. Ultrasound produces heating, pressure changes and mechanical disturbances in tissue. Diagnostic levels of ultrasound can produce temperature rises that are hazardous to sensitive organs and the embryo/fetus. Biological effects of non-thermal origin have been reported in animals but, to date, no such effects have been demonstrated in humans, except when a micro-bubble
contrast agent A contrast agent (or contrast medium) is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance, a material with a definite chemical composition * Matter, an ...
is present.
Nonetheless, care should be taken to use low power settings and avoid pulsed wave scanning of the fetal brain unless specifically indicated in high risk pregnancies. Figures released for the period 2005–2006 by the UK Government (Department of Health) show that non-obstetric ultrasound examinations constituted more than 65% of the total number of ultrasound scans conducted.

# Hemodynamics (blood circulation)

Blood velocity can be measured in various blood vessels, such as
middle cerebral artery The middle cerebral artery (MCA) is one of the three major paired cerebral artery, arteries that supply blood to the cerebrum. The MCA arises from the internal carotid and continues into the lateral sulcus where it then branches and projects to man ...
or
descending aorta The descending aorta is part of the aorta The aorta ( ) is the main and largest artery An artery (plural arteries) () is a blood vessel The blood vessels are the components of the circulatory system The circulatory system, also ...
, by relatively inexpensive and low risk ultrasound Doppler probes attached to portable monitors. These provide non-invasive or transcutaneous (non-piercing) minimal invasive blood flow assessment. Common examples are,
Transcranial Doppler Transcranial Doppler (TCD) and transcranial color Doppler (TCCD) are types of Doppler ultrasonography Doppler ultrasonography is medical ultrasonography Medical ultrasound (also known as diagnostic sonography or ultrasonography) is a medical ...

,
Esophogeal Doppler In medicine, Esophageal Doppler or Oesophageal Doppler uses a small ultrasound probe inserted into the esophagus through the nose or mouth to measure blood velocity in the descending aorta. It is minimally invasive (does not break the skin) and is ...
and Suprasternal Doppler.

Most structures of the neck, including the
thyroid The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobe (anatomy), lobes. The lower two thirds of the lobes are connected by a thin band of Connective tissue, tissue call ...

and
parathyroid gland Parathyroid glands are small endocrine The endocrine system is a messenger system comprising feedback loops of the hormone A hormone (from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ε ...
s,
lymph nodes A lymph node, or lymph gland, is a kidney-shaped Organ (anatomy), organ of the lymphatic system, and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lympho ...
, and
salivary glands The salivary glands in mammal Mammals (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'' ...

, are well-visualized by high-frequency ultrasound with exceptional anatomic detail. Ultrasound is the preferred imaging modality for thyroid tumors and lesions, and its use is important in the evaluation, preoperative planning, and postoperative surveillance of patients with
thyroid cancer Thyroid cancer is cancer that develops from the Tissue (biology), tissues of the thyroid gland. It is a disease in which cell (biology), cells grow abnormally and have the potential to metastasize, spread to other parts of the body. Symptoms can ...

. Many other benign and malignant conditions in the head and neck can be differentiated, evaluated, and managed with the help of diagnostic ultrasound and ultrasound-guided procedures.

# Neonatology

In
neonatology Neonatology is a subspecialty of pediatrics that consists of the medical care of newborn infants, especially the ill or premature newborn. It is a hospital-based specialty, and is usually practised in neonatal intensive care units (NICUs). The ...
,
transcranial Doppler Transcranial Doppler (TCD) and transcranial color Doppler (TCCD) are types of Doppler ultrasonography Doppler ultrasonography is medical ultrasonography Medical ultrasound (also known as diagnostic sonography or ultrasonography) is a medical ...

can be used for basic assessment of intracerebral structural abnormalities, suspected hemorrhage,
ventriculomegaly Ventriculomegaly is a brain condition that mainly occurs in the fetus when the lateral ventricles become dilated. The most common definition uses a width of the atrium of the lateral ventricle of greater than 10 mm. This occurs in around 1% ...
or
hydrocephalus :''This article concerns the medical condition. For the hydrocephalus creature in American folklore that bares this condition as a part of its legend, see melon heads In the American folklore of Ohio, Michigan and Connecticut, Melon Heads are b ...

and anoxic insults (
Periventricular leukomalacia Periventricular leukomalacia (PVL) is a form of white-matter brain injury, characterized by the necrosis (more often coagulation) of white matter near the lateral ventricles.Vlasyuk V.V. Periventricular leukomalacia in children. SPb, "Гелик ...
). It can be performed through the soft spots in the skull of a newborn infant (
Fontanelle A fontanelle (or fontanel) (colloquially, soft spot) is an anatomical Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, ...

) until these completely close at about 1 year of age by which time they have formed a virtually impenetrable acoustic barrier to ultrasound. The most common site for cranial ultrasound is the anterior fontanelle. The smaller the fontanelle, the more the image is compromised.

# Ophthalmology ()

In
ophthalmology Ophthalmology () is a branch of medicine and surgery that deals with the diagnosis and treatment of disorders of the eye. An ophthalmologist is a physician who Specialty (medicine), specializes in ophthalmology. The credentials include a degree i ...
and
optometry Optometry is a specialized health care profession that involves examining the eyes and related structures for defects or abnormalities. This often involves prescribing corrective lenses and providing medical eye care. Optometrists (Doctors of Op ...
, there are two major forms of eye exam using ultrasound: * A-scan ultrasound biometry, is commonly referred to as an ''A-scan'' (''Amplitude scan''). A-mode provides data on the length of the
eye Eyes are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized as parenchyma Parenchyma () is t ...

, which is a major determinant in common sight disorders, especially for determining the power of an intraocular lens after cataract extraction. *''B-scan ultrasonography'', or ''B-scan'', is a B-mode scan that produces a cross-sectional view of the
eye Eyes are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized as parenchyma Parenchyma () is t ...

and the
orbit In celestial mechanics, an orbit is the curved trajectory of an physical body, object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an satellite, artificial satellite around an object or po ...
. Its use in the emergency department for the timely diagnosis of conditions such as retinal or vitreous detachment, retinal and vitreous hemorrhages, and intra-ocular foreign bodies is common and important.

# Pulmonology (lungs)

Ultrasound is used to assess the
lung The lungs are the primary organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized as parenchyma ...

s in a variety of settings including critical care, emergency medicine, trauma surgery, as well as general medicine. This imaging modality is used at the bedside or examination table to evaluate a number of different lung abnormalities as well as to guide procedures such as
thoracentesis Thoracentesis , also known as thoracocentesis (from the Greek ''thōrax'' "chest, thorax"— GEN ''thōrakos''—and ''kentēsis'' "pricking, puncture"), pleural tap, needle thoracostomy, or needle decompression (often used term) is an invasive ...

, (drainage of pleural fluid (effusion)), needle aspiration biopsy, and
catheter In medicine Medicine is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organizes knowledge in the form of Testability, testabl ...

placement. Although air present in the lungs does not allow good penetration of ultrasound waves, interpretation of specific artifacts created on the lung surface can be used to detect abnormalities.

## Lung ultrasound basics

* The Normal Lung Surface: The lung surface is composed of visceral and parietal
pleura The pulmonary pleurae (''sing.'' pleura) are the two opposing layers of serous membrane In anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology Biology is the natural science that studies life and living orga ...
. These two surfaces are typically pushed together and make up the pleural line, which is the basis of lung (or pleural) ultrasound. This line is visible less than a centimeter below the rib line in most adults. On ultrasound, it is visualized as a hyperechoic (bright white) horizontal line if the ultrasound probe is applied perpendicularly to the skin. * Artifacts: Lung ultrasound relies on artifacts, which would otherwise be considered a hindrance in imaging. Air blocks the ultrasound beam and thus visualizing healthy lung tissue itself with this mode of imaging is not practical. Consequently, physicians and sonographers have learned to recognize patterns that ultrasound beams create when imaging healthy versus diseased lung tissue. Three commonly seen and utilized artifacts in lung ultrasound include lung sliding, A-lines, and B-lines. ** §  Lung Sliding: The presence of lung sliding, which indicates the shimmering of the pleural line that occurs with movement of the visceral and parietal pleura against one another with respiration (sometimes described as 'ants marching'), is the most important finding in normal aerated lung. Lung sliding indicates both that the lung is present at the chest wall and that the lung is functioning. ** §  A-lines: When the ultrasound beam makes contact with the pleural line, it is reflected back creating a bright white horizontal line. The subsequent reverberation artifacts that appear as equally spaced horizontal lines deep to the pleura are A-lines. Ultimately, A-lines are a reflection of the ultrasound beam from the pleura with the space between A-lines corresponding to the distance between the parietal pleura and the skin surface. A-lines indicate the presence of air, which means that these artifacts can be present in normal healthy lung (and also in patients with pneumothorax). ** §  B-lines: B-lines are also reverberation artifacts. They are visualized as hyperechoic vertical lines extending from the pleura to the edge of the ultrasound screen. These lines are sharply defined and laser-like and typically do not fade as they progress down the screen. A few B-lines that move along with the sliding pleura can be seen in normal lung due to acoustic impedance differences between water and air. However, excessive B-lines (three or more) are abnormal and are typically indicative of underlying lung pathology.

## Lung pathology assessed with ultrasound

*
Pulmonary edema Pulmonary edema (PE), also known as pulmonary congestion, is liquid accumulation in the tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a ...

: Lung ultrasound has been shown to be very sensitive for the detection of pulmonary edema. It allows for improvement in diagnosis and management of critically ill patients, particularly when used in combination with echocardiography. The sonographic feature that is present in pulmonary edema is multiple B-lines. B-lines can occur in a healthy lung; however, the presence of 3 or more in the anterior or lateral lung regions is always abnormal. In pulmonary edema, B-lines indicate an increase in the amount of water contained in the lungs outside of the pulmonary vasculature. B-lines can also be present in a number of other conditions including pneumonia, pulmonary contusion, and lung infarction. Additionally, it is important to note that there are multiple types of interactions between the pleural surface and the ultrasound wave that can generate artifacts with some similarity to B-lines but which do not have pathologic significance. *
Pneumothorax A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and dyspnea, shortness of breath. In a minority of cases, a one-way ...

: In clinical settings when pneumothorax is suspected, lung ultrasound can aid in diagnosis. In pneumothorax, air is present between the two layers of the pleura and lung sliding on ultrasound is therefore absent. The
negative predictive value The positive and negative predictive values (PPV and NPV respectively) are the proportions of positive and negative results in Predictive value of tests, statistics and diagnostic tests that are true positive and true negative results, respective ...
for lung sliding on ultrasound is reported as 99.2–100% - briefly, if lung sliding is present, a pneumothorax is effectively ruled out. The absence of lung sliding, however, is not necessarily specific for pneumothorax as there are other conditions that also cause this finding including
acute respiratory distress syndrome Acute respiratory distress syndrome (ARDS) is a type of respiratory failure Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal l ...
, lung consolidations, pleural adhesions, and
pulmonary fibrosis Pulmonary fibrosis is a condition in which the lungs become scarred over time. Symptoms include shortness of breath, a dry cough, feeling tired, weight loss, and nail clubbing. Complications may include pulmonary hypertension, respiratory failure ...
. *
Pleural effusion A pleural effusion is accumulation of excessive fluid in the pleural space, the potential space that surrounds each lung. Under normal conditions, pleural fluid is secreted by the parietal pleural capillaries at a rate of 0.01 millilitre per kilo ...

: Lung ultrasound is a cost-effective, safe, and non-invasive imaging method that can aid in the prompt visualization and diagnosis of pleural effusions. Effusions can be diagnosed by a combination of physical exam, percussion, and
auscultation :''For the ancient monasterial worker, see Auscultare'' Auscultation (based on the Latin verb ''auscultare'' "to listen") is listening to the internal sounds of the body, usually using a stethoscope The stethoscope is an acoustic medical ...

of the chest. However, these exam techniques can be complicated by a variety of factors including the presence of
mechanical ventilation Mechanical ventilation, assisted ventilation or intermittent mandatory ventilationIntermittent Mandatory Ventilation (IMV) refers to any mode of mechanical ventilation where a regular series of breaths are scheduled but the ventilator senses p ...
, obesity, or patient positioning, all of which reduce the sensitivity of the physical exam. Consequently, lung ultrasound can be an additional tool to augment plain chest Xray and
chest CT A CT scan or computed tomography scan (formerly known as computed axial tomography or CAT scan) is a medical image, imaging Scientific technique, technique used in radiology to obtain detailed internal images of the body noninvasively for Diagno ...

. Pleural effusions on ultrasound appear as structural images within the thorax rather than an artifact. They will typically have four distinct borders including the pleural line, two rib shadows, and a deep border. In critically ill patients with pleural effusion, ultrasound may guide procedures including needle insertion,
thoracentesis Thoracentesis , also known as thoracocentesis (from the Greek ''thōrax'' "chest, thorax"— GEN ''thōrakos''—and ''kentēsis'' "pricking, puncture"), pleural tap, needle thoracostomy, or needle decompression (often used term) is an invasive ...

, and chest-tube insertion. *
Lung cancer Lung cancer, also known as lung carcinoma, since about 98–99% of all lung cancers are carcinomas, is a malignant lung tumor characterized by uncontrolled cell growth in tissue (biology), tissues of the lung. Lung carcinomas derive from trans ...

staging: In
pulmonology Pulmonology (, , from Latin ''pulmō, -ōnis'' "lung" and the Ancient Greek, Greek suffix "study of") or pneumology (, built on Greek πνεύμων "lung") is a specialty (medicine), medical specialty that deals with Respiratory disease, di ...
, endobronchial ultrasound (EBUS) probes are applied to standard flexible endoscopic probes and used by pulmonologists to allow for direct visualization of endobronchial lesions and lymph nodes prior to transbronchial needle aspiration. Among its many uses, EBUS aids in lung cancer staging by allowing for lymph node sampling without the need for major surgery. *
COVID-19 Coronavirus disease 2019 (COVID-19) is a contagious disease A contagious disease is a disease A disease is a particular abnormal condition that negatively affects the structure A structure is an arrangement and organization o ...

: Lung ultrasound has proved useful in the diagnosis of COVID-19 especially in cases where other investigations are not available.

# Urinary tract

Ultrasound is routinely used in
urology Urology (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approxima ...
to determine the amount of fluid retained in a patient's bladder. In a pelvic sonogram, images include the
uterus The uterus (from Latin "uterus", plural ''uteri'') or womb () is the main female hormone-responsive, sex organ, secondary sex organ of the reproductive system in humans and most other mammals. Things occurring in the uterus are described with t ...

and
ovaries The ovary is an organ found in the female reproductive system 300px, 1. Labia_majora.html"_;"title="Vulva: 2. Labia_majora">Vulva: 2. Labia_majora; 3. Labia_minora; 4. Vulval_vestibule.html" "title="Labia_minora.html ...

or
urinary bladder The urinary bladder, or simply bladder, is a hollow Muscle, muscular organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a hollow distensible organ that sits on the pel ...
in females. In males, a sonogram will provide information about the bladder,
prostate The prostate is both an accessory gland of the male reproductive system The male reproductive system consists of a number of sex organ A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual repr ...

, or
testicles Testicle or testis (plural testes) is the male Male (♂) is the sex of an organism that produces the gamete known as sperm. A male gamete can fuse with a larger female gamete, or ovum, in the process of fertilization. A male cannot sexual r ...

(for example to urgently distinguish
epididymitis Epididymitis is a medical condition characterized by inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a prot ...
from
testicular torsion Testicular torsion occurs when the spermatic cord The spermatic cord is the cord-like structure in males formed by the vas deferens (''ductus deferens'') and surrounding tissue that runs from the deep inguinal ring down to each testicle. Its Serou ...
). In young males, it is used to distinguish more benign testicular masses (
varicocele A varicocele is an abnormal enlargement of the pampiniform venous plexus in the scrotum. This plexus of veins drains blood from the testicles back to the heart. The blood vessel, vessels originate in the abdomen and course down through the inguinal ...

or
hydrocele A hydrocele is an accumulation of serous fluid in a body cavity. A hydrocele testis is the accumulation of fluids around a testicle Testicle or testis (plural testes) is the male reproductive gland or gonad A gonad, sex gland, or repro ...
) from
testicular cancer Testicular cancer is cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most ...

, which is curable but must be treated to preserve health and fertility. There are two methods of performing pelvic sonography – externally or internally. The internal pelvic sonogram is performed either trans
vagina In mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the class (biology), class Mammalia (), and characterized by the presence of mammary glands which in Female#Mammalian female, femal ...

lly (in a woman) or transrectally (in a man). Sonographic imaging of the pelvic floor can produce important diagnostic information regarding the precise relationship of abnormal structures with other pelvic organs and it represents a useful hint to treat patients with symptoms related to pelvic prolapse, double incontinence and obstructed defecation. It is also used to diagnose and, at higher frequencies, to treat (break up) kidney stones or kidney crystals (
nephrolithiasis Kidney stone disease, also known as nephrolithiasis or urolithiasis, is when a solid piece of material (kidney stone) develops in the urinary tract. Kidney stones typically form in the kidney and leave the body in the urine stream. A small ston ...
).

# Penis and scrotum

Scrotal ultrasonography is used in the evaluation of
testicular pain Testicular pain, also known as scrotal pain, occurs when part or all of either one or both testicles hurt. Pain in the scrotum The scrotum or scrotal sac is an Anatomy, anatomical male reproductive structure located Anatomical terms of locatio ...
, and can help identify solid masses. Ultrasound is an excellent method for the study of the
penis A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during Copulation (zoology), copulation. Such organs occur in many animals, both #Vertebrates, vertebrate ...

, such as indicated in trauma, priapism, erectile dysfunction or suspected
Peyronie's disease Peyronie's disease is a connective tissue disorder involving the growth of fibrous plaques in the soft tissue of the Human penis, penis. Specifically, scar tissue forms in the Tunica albuginea (penis), tunica albuginea, the thick sheath of tissue ...

.Originally copied from:

# Musculoskeletal

Musculoskeletal The human musculoskeletal system (also known as the human locomotor system, and previously the activity system) is an organ system An organ system is a biological system A biological system is a complex biological network, network which conne ...
ultrasound is used to examine tendons, muscles, nerves, ligaments, soft tissue masses, and bone surfaces. It is helpful in diagnosing ligament sprains, muscles strains and joint pathology. It is an alternative or supplement to x-ray imaging in detecting fractures of the wrist, elbow and shoulder for patients up to 12 years ( Fracture sonography). Quantitative ultrasound is an adjunct musculoskeletal test for myopathic disease in children; estimates of lean body mass in adults; proxy measures of muscle quality (i.e., tissue composition) in older adults with
sarcopenia Sarcopenia is a type of muscle loss (muscle atrophy Muscle atrophy is the loss of skeletal muscle mass. It can be caused by immobility, aging, malnutrition, medications, or a wide range of injuries or diseases that impact the musculoskeletal or n ...
Ultrasound can also be used for needle guidance in muscle or joint injections, as in ultrasound-guided hip joint injection.

# Kidneys

In
nephrology Nephrology (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approxi ...
, ultrasonography of the kidneys is essential in the diagnosis and management of kidney-related diseases. The kidneys are easily examined, and most pathological changes are distinguishable with ultrasound. It is an accessible, versatile, relatively economic, and fast aid for decision-making in patients with renal symptoms and for guidance in renal intervention.Content initially copied from:
(CC-BY 4.0)
/ref> Using B-mode imaging, assessment of renal anatomy is easily performed, and US is often used as image guidance for renal interventions. Furthermore, novel applications in renal US have been introduced with contrast-enhanced ultrasound (CEUS), elastography and fusion imaging. However, renal US has certain limitations, and other modalities, such as CT (CECT) and MRI, should be considered for supplementary imaging in assessing renal disease.

# Venous Access

Intravenous access, for the collection of blood samples to assist in diagnosis or laboratory investigation including blood culture, or for administration of intravenous fluids for fluid maintenance of replacement or blood transfusion in sicker patients, is a common medical procedure. The need for intravenous access occurs in the outpatient laboratory, in the inpatient hospital units, and most critically in the Emergency Room and Intensive Care Unit. In many situations, intravenous access may be required repeatedly or over a significant time period. In these latter circumstances, a needle with an overlying catheter is introduced into the vein and the catheter is then inserted securely into the vein while the needle is withdrawn. The chosen veins are most frequently selected from the arm, but in challenging situations, a deeper vein from the neck (
external jugular vein The external jugular vein receives the greater part of the blood from the exterior of the Human cranium, cranium and the deep parts of the face, being formed by the junction of the posterior division of the retromandibular vein with the posterior a ...

) or upper arm (
subclavian vein The subclavian vein is a paired large vein Veins are blood vessels The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an Biological sys ...
) may need to be used. There are many reasons why the selection of a suitable vein may be problematic. These include, but are not limited to, obesity, previous injury to veins from inflammatory reaction to previous ‘blood draws’, previous injury to veins from recreational drug use. In these challenging situations, the insertion of a catheter into a vein has been greatly assisted by the use of ultrasound. The ultrasound unit may be ‘cart-based’ or ‘handheld’ using a linear transducer with a frequency of 10 to 15
megahertz The hertz (symbol: Hz) is the unit Unit may refer to: Arts and entertainment * UNIT Unit may refer to: Arts and entertainment * UNIT, a fictional military organization in the science fiction television series ''Doctor Who'' * Unit of action ...

. In most circumstances, choice of vein will be limited by the requirement that the vein is within 1.5 cms. from the skin surface. The transducer may be placed longitudinally or transversely over the chosen vein. Ultrasound training for intravenous cannulation is offered in most ultrasound training programs.

# From sound to image

The creation of an image from sound has three steps – transmitting a
sound wave In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, its Motion (physics), motion and behavior throug ...

, receiving echoes, and interpreting those echoes.

## Producing a sound wave

A sound wave is typically produced by a
piezoelectric Piezoelectricity (, ) is the electric charge Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carrie ...
transducer A transducer is a device that converts Religious conversion is the adoption of a set of beliefs identified with one particular religious denomination A religious denomination is a subgroup within a religion Religion is a social system ...

encased in a plastic housing. Strong, short electrical pulses from the ultrasound machine drive the transducer at the desired frequency. The
frequencies Frequency is the number of occurrences of a repeating event per unit of time A unit of time is any particular time interval, used as a standard way of measuring or expressing duration. The SI base unit, base unit of time in the Internation ...

can vary between 1 and 18
MHz The hertz (symbol: Hz) is the derived unit of frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and an ...
, though frequencies up to 50–100 megahertz have been used experimentally in a technique known as biomicroscopy in special regions, such as the anterior chamber of the eye. Older technology transducers focused their beam with physical lenses. Contemporary technology transducers use
digital antenna array Digital antenna array (DAA) is smart antenna with multi channels digital beamforming, usually by using fast Fourier transform (FFT). The development and practical realization of digital antenna arrays theory started in 1962 under the guidance of ...

techniques (piezoelectric elements in the transducer produce echos at different times) to enable the ultrasound machine to change the direction and depth of focus. As stated, the sound is focused either by the shape of the transducer, a lens in front of the transducer, or a complex set of control pulses from the ultrasound scanner, in the
beamforming Beamforming or spatial filtering is a signal processing Signal processing is an electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and system ...

or spatial filtering technique. This focusing produces an arc-shaped sound wave from the face of the transducer. The wave travels into the body and comes into focus at a desired depth. Materials on the face of the transducer enable the sound to be transmitted efficiently into the body (often a rubbery coating, a form of
impedance matching In electronics The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons The electron is a subatomic particle In physical sciences, subatomic particles ...
). In addition, a water-based gel is placed between the patient's skin and the probe to facilitate ultrasound transmission into the body. This is because air causes total reflection of ultrasound; impeding the transmission of ultrasound into the body. The sound wave is partially reflected from the layers between different tissues or scattered from smaller structures. Specifically, sound is reflected anywhere where there are acoustic impedance changes in the body: e.g.
blood cell A blood cell, also called a hematopoietic cell, hemocyte, or hematocyte, is a cell produced through hematopoiesis Haematopoiesis (, from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ...

s in
blood plasma Blood plasma is a yellowish liquid component of blood Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the Cell (biology), cells and transports metabolic waste products ...
, small structures in organs, etc. Some of the reflections return to the transducer.

## Receiving the echoes

The return of the sound wave to the transducer results in the same process as sending the sound wave, in reverse. The returned sound wave vibrates the transducer and the transducer turns the vibrations into electrical pulses that travel to the ultrasonic scanner where they are processed and transformed into a digital image.

## Forming the image

To make an image, the ultrasound scanner must determine two characteristics from each received echo: # How long it took the echo to be received from when the sound was transmitted. (Time and distance are equivalent.) # How strong the echo was. Once the ultrasonic scanner determines these two, it can locate which pixel in the image to illuminate and with what intensity. Transforming the received signal into a digital image may be explained by using a blank spreadsheet as an analogy. First picture a long, flat transducer at the top of the sheet. Send pulses down the 'columns' of the spreadsheet (A, B, C, etc.). Listen at each column for any return echoes. When an echo is heard, note how long it took for the echo to return. The longer the wait, the deeper the row (1,2,3, etc.). The strength of the echo determines the brightness setting for that cell (white for a strong echo, black for a weak echo, and varying shades of grey for everything in between.) When all the echoes are recorded on the sheet, a greyscale image has been accomplished.

## Displaying the image

Images from the ultrasound scanner are transferred and displayed using the
DICOM Digital Imaging and Communications in Medicine (DICOM) is the standard for the communication and management of medical imaging information and related data. DICOM is most commonly used for storing and transmitting In electronics Electronics c ...
standard. Normally, very little post processing is applied.

# Sound in the body

Ultrasonography (
sonography Medical ultrasound (also known as diagnostic sonography or ultrasonography) is a diagnostic imaging technique, or therapeutic application of ultrasound Ultrasound is sound waves with frequency, frequencies higher than the upper audible ...

) uses a probe containing multiple acoustic
transducer A transducer is a device that converts Religious conversion is the adoption of a set of beliefs identified with one particular religious denomination A religious denomination is a subgroup within a religion Religion is a social system ...

s to send pulses of sound into a material. Whenever a sound wave encounters a material with a different density (acoustical impedance), some of the sound wave is scattered but part is reflected back to the probe and is detected as an echo. The time it takes for the
echo In audio signal processing Audio signal processing is a subfield of signal processing that is concerned with the electronic manipulation of audio signals. Audio signals are electronic representations of sound waves—longitudinal waves whic ...
to travel back to the probe is measured and used to calculate the depth of the tissue interface causing the echo. The greater the difference between acoustic impedances, the larger the echo is. If the pulse hits gases or solids, the density difference is so great that most of the acoustic energy is reflected and it becomes impossible to progress further. The frequencies used for medical imaging are generally in the range of 1 to 18 MHz. Higher frequencies have a correspondingly smaller wavelength, and can be used to make more detailed sonograms. However, the attenuation of the sound wave is increased at higher frequencies, so penetration of deeper tissues necessitates a lower frequency (3–5 MHz). Penetrating deep into the body with sonography is difficult. Some acoustic energy is lost each time an echo is formed, but most of it (approximately $\textstyle 0.5 \frac$) is lost from acoustic absorption. (See
Acoustic attenuationAcoustic attenuation is a measure of the energy In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, ...
for further details on modeling of acoustic attenuation and absorption.) The speed of sound varies as it travels through different materials, and is dependent on the acoustical impedance of the material. However, the sonographic instrument assumes that the acoustic velocity is constant at 1540 m/s. An effect of this assumption is that in a real body with non-uniform tissues, the beam becomes somewhat de-focused and image resolution is reduced. To generate a 2-D image, the ultrasonic beam is swept. A transducer may be swept mechanically by rotating or swinging or a 1-D
phased array In antenna Antenna (pl. antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the ...
transducer may be used to sweep the beam electronically. The received data is processed and used to construct the image. The image is then a 2-D representation of the slice into the body. 3-D images can be generated by acquiring a series of adjacent 2-D images. Commonly a specialized probe that mechanically scans a conventional 2-D image transducer is used. However, since the mechanical scanning is slow, it is difficult to make 3D images of moving tissues. Recently, 2-D phased array transducers that can sweep the beam in 3-D have been developed. These can image faster and can even be used to make live 3-D images of a beating heart. ultrasonography is used to study blood flow and muscle motion. The different detected speeds are represented in color for ease of interpretation, for example leaky heart valves: the leak shows up as a flash of unique color. Colors may alternatively be used to represent the amplitudes of the received echoes.

# Modes

Several modes of ultrasound are used in medical imaging. These are: *A-mode: A-mode (amplitude mode) is the simplest. A single transducer scans a line through the body with the echoes plotted on screen as a function of depth.
Therapeutic ultrasound Therapeutic ultrasound refers generally to any type of ultrasonic procedure that uses ultrasound Ultrasound is s with higher than the upper audible limit of human . Ultrasound is not different from "normal" (audible) sound in its physical ...
aimed at a specific tumor or calculus is A-mode, to allow for pinpoint accurate focus of the destructive wave energy. *B-mode or 2D mode: In B-mode (brightness mode), a linear array of transducers simultaneously scans a plane through the body that can be viewed as a two-dimensional image on screen. More commonly known as 2D mode now. :*B-flow is a mode that digitally highlights moving reflectors (mainly
red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek language, Greek ''erythros'' for "red" and ''k ...

s) while suppressing the signals from the surrounding stationary tissue. It can visualize flowing blood and surrounding stationary tissues simultaneously. It is thus an alternative or complement to
Doppler ultrasonography Doppler ultrasonography is medical ultrasonography Medical ultrasound (also known as diagnostic sonography or ultrasonography) is a medical imaging, diagnostic imaging technique, or therapeutic ultrasound, therapeutic application of ultrasound ...
in visualizing blood flow. *C-mode: A C-mode image is formed in a plane normal to a B-mode image. A gate that selects data from a specific depth from an A-mode line is used; then the transducer is moved in the 2D plane to sample the entire region at this fixed depth. When the transducer traverses the area in a spiral, an area of 100 cm2 can be scanned in around 10 seconds. *M-mode: In M-mode (motion mode), pulses are emitted in quick succession – each time, either an A-mode or B-mode image is taken. Over time, this is analogous to recording a
video Video is an electronic Electronic may refer to: *Electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matter. It uses active d ...

in ultrasound. As the organ boundaries that produce reflections move relative to the probe, this can be used to determine the velocity of specific organ structures. * Doppler mode: This mode makes use of the Doppler effect in measuring and visualizing blood flow **Color Doppler: Velocity information is presented as a color-coded overlay on top of a B-mode image **Continuous wave (CW) Doppler: Doppler information is sampled along a line through the body, and all velocities detected at each time point are presented (on a time line) **Pulsed wave (PW) Doppler: Doppler information is sampled from only a small sample volume (defined in 2D image), and presented on a timeline ** Duplex: a common name for the simultaneous presentation of 2D and (usually) PW Doppler information. (Using modern ultrasound machines, color Doppler is almost always also used; hence the alternative name Triplex.) *Pulse inversion mode: Two successive pulses with opposite sign are emitted and then subtracted from each other. This implies that any linearly responding constituent will disappear while gases with non-linear compressibility stand out. Pulse inversion may also be used in a similar manner as in Harmonic mode; see below: *Harmonic mode: A deep penetrating fundamental frequency is emitted into the body and a harmonic overtone is detected. Noise and artifacts due to reverberation and aberration are greatly reduced. Some also believe that penetration depth can be gained with improved lateral resolution; however, this is not well documented.

# Expansions

An additional expansion of ultrasound is bi-planar ultrasound, in which the probe has two 2D planes perpendicular to each other, providing more efficient localization and detection. Furthermore, an omniplane probe can rotate 180° to obtain multiple images.Page 161 (part II > Two-dimensional Echocardiography) in: In 3D ultrasound, many 2D planes are digitally added together to create a 3-dimensional image of the object.

## Doppler ultrasonography

Doppler ultrasonography Doppler ultrasonography is medical ultrasonography Medical ultrasound (also known as diagnostic sonography or ultrasonography) is a medical imaging, diagnostic imaging technique, or therapeutic ultrasound, therapeutic application of ultrasound ...
employs the
Doppler effect The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency Frequency is the number of occurrences of a repeating event per unit of time A unit of time is any particular time Time is the ...

to assess whether structures (usually blood) are moving towards or away from the probe, and their relative velocity. By calculating the frequency shift of a particular sample volume, flow in an artery or a jet of blood flow over a heart valve, its speed and direction can be determined and visualized, as an example. ''Color Doppler'' is the measurement of velocity by color scale. Color Doppler images are generally combined with gray scale ( B-mode) images to display ''duplex ultrasonography'' images. Uses include: * Doppler echocardiography is the use of Doppler ultrasonography to examine the
heart The heart is a muscular MUSCULAR (DS-200B), located in the United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,Usage is mixed. The Guardian' and Telegraph' use ...

. An echocardiogram can, within certain limits, produce accurate assessment of the direction of
blood flow Hemodynamics or haemodynamics are the dynamics Dynamics (from Greek language, Greek δυναμικός ''dynamikos'' "powerful", from δύναμις ''dynamis'' "power (disambiguation), power") or dynamic may refer to: Physics and engineering * ...

and the
velocity The velocity of an object is the rate of change of its position with respect to a frame of reference In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical scie ...

of blood and cardiac tissue at any arbitrary point using the Doppler effect. Velocity measurements allow assessment of
cardiac valve A heart valve is a Check valve, one-way valve that allows blood flow, blood to flow in one direction through the chambers of the heart. Four valves are usually present in a mammalian heart and together they determine the pathway of blood flow throu ...
areas and function, abnormal communications between the left and right side of the heart, leaking of blood through the valves ( valvular regurgitation), and calculation of the
cardiac output Cardiac output (CO), also known as heart output denoted by the symbols Q, or \dot Q_ , is a term used in cardiac physiology Cardiac physiology or heart function is the study of healthy, unimpaired function of the heart: involving blood flow; ...
and
E/A ratioThe E/A ratio is a marker of the function of the left ventricle of the heart. It represents the ratio of peak velocity blood flow from left ventricular relaxation in early diastole (the E wave) to peak velocity flow in late diastole caused by atrial ...

Abdul Latif Mohamed, Jun Yong, Jamil Masiyati, Lee Lim, Sze Chec Tee. ''The Prevalence Of Diastolic Dysfunction In Patients With Hypertension Referred For Echocardiographic Assessment of Left Ventricular Function.'' Malaysian Journal of Medical Sciences, Vol. 11, No. 1, January 2004, pp. 66-74
(a measure of
diastolic dysfunction Heart failure with preserved ejection fraction (HFpEF) is a form of heart failure in which the ejection fraction – the percentage of the volume of blood ejected from the left ventricle with each heartbeat divided by the volume of blood when the le ...
). Contrast-enhanced ultrasound using gas-filled microbubble contrast media can be used to improve velocity or other flow-related measurements of interest. *
Transcranial Doppler Transcranial Doppler (TCD) and transcranial color Doppler (TCCD) are types of Doppler ultrasonography Doppler ultrasonography is medical ultrasonography Medical ultrasound (also known as diagnostic sonography or ultrasonography) is a medical ...

(TCD) and transcranial color Doppler (TCCD), measure the velocity of
blood flow Hemodynamics or haemodynamics are the dynamics Dynamics (from Greek language, Greek δυναμικός ''dynamikos'' "powerful", from δύναμις ''dynamis'' "power (disambiguation), power") or dynamic may refer to: Physics and engineering * ...

through the
brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tis ...

's
blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to circulate and transport nutrients (such as amino ...
s through the
cranium The skull is a bone A bone is a Stiffness, rigid tissue (anatomy), tissue that constitutes part of the vertebrate skeleton in animals. Bones protect the various organs of the body, produce red blood cell, red and white blood cells, store mi ...

. They are useful in the diagnosis of
emboli An embolism is the lodging of an embolus An embolus (; plural emboli; from the Greek ἔμβολος "wedge", "plug") is an unattached mass that travels through the bloodstream The circulatory system, also called the cardiovascular system ...
,
stenosis A stenosis (from Ancient Greek στενός, "narrow") is an abnormal narrowing in a blood vessel or other tubular Organ (anatomy), organ or structure such as foramina and canals. It is also sometimes called a stricture (as in urethral stricture) ...
,
vasospasm Vasospasm refers to a condition in which an arterial spasm leads to vasoconstriction. This can lead to tissue ischemia and tissue death (necrosis). Cerebral vasospasm may arise in the context of subarachnoid hemorrhage Subarachnoid hemorrhage ...
from a subarachnoid
hemorrhage Bleeding, also known as a hemorrhage, haemorrhage, or simply blood loss, is blood Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the Cell (biology), cells and transports ...
(bleeding from a ruptured
aneurysm An aneurysm is an outward bulging, likened to a bubble or balloon, caused by a localized, abnormal, weak spot on a blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the ca ...
), and other problems. *
Doppler fetal monitor A Doppler fetal monitor is a hand-held ultrasound transducer used to detect the fetal heartbeat for prenatal care. It uses the Doppler effect to provide an audible simulation of the heart beat. Some models also display the heart rate in beats per ...
s use the Doppler effect to detect the
fetal heartbeat Heart development (also known as cardiogenesis) refers to the prenatal development Prenatal development () includes the development of the embryo and of the foetus during a viviparous animal's gestation. Prenatal development starts with ferti ...
during
prenatal care Prenatal care, also known as antenatal care, is a type of preventive healthcare Preventive healthcare, or prophylaxis, consists of measures taken for disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing ...
. These are hand-held, and some models also display the
heart rate Heart rate is the speed of the heartbeat Heartbeat or heartbeats may refer to: Physiology *Cardiac cycle, of the heart *Contraction of the cardiac muscle, muscles of the heart, or a perceived effect of it, such as: **Heart sounds, the noises gene ...

in beats per minute (BPM). Use of this monitor is sometimes known as ''Doppler
auscultation :''For the ancient monasterial worker, see Auscultare'' Auscultation (based on the Latin verb ''auscultare'' "to listen") is listening to the internal sounds of the body, usually using a stethoscope The stethoscope is an acoustic medical ...

''. The Doppler fetal monitor is commonly referred to simply as a ''Doppler'' or ''fetal Doppler'' and provides information similar to that provided by a
fetal stethoscope A Pinard horn is a type of stethoscope used to listen to the heart rate of a fetus during pregnancy. It is a hollow horn, often made of wood or metal, about long. It functions similarly to an ear trumpet by amplifying sound. The user holds the wid ...
.

## Contrast ultrasonography (ultrasound contrast imaging)

A
contrast medium A contrast agent (or contrast medium) is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance, a material with a definite chemical composition * Matter, an ...
for medical ultrasonography is a formulation of encapsulated gaseous microbubbles to increase
echogenicity Echogenicity (misspelled sometimes as echogenecity) or ''echogeneity'' is the ability to bounce an echo, e.g. return the signal in ultrasound Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human ...
of blood, discovered by Dr Raymond Gramiak in 1968 and named
contrast-enhanced ultrasound Contrast-enhanced ultrasound (CEUS) is the application of ultrasound Ultrasound is sound wave In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is ...
. This contrast
medical imaging Medical imaging is the technique and process of imaging Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of an image). Imaging technology is the application of materi ...
modality is used throughout the world, for
echocardiography An echocardiography, echocardiogram, cardiac echo or simply an echo, is an of the . It is a type of of the heart, using standard ultrasound or . Echocardiography has become routinely used in the diagnosis, management, and follow-up of patients ...
in particular in the United States and for
ultrasound Ultrasound is s with higher than the upper audible limit of human . Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is appro ...

radiology Radiology is the medical discipline that uses medical imaging Medical imaging is the technique and process of imaging Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the form ...

in
Europe Europe is a continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of scienc ...

and
Asia Asia () is Earth's largest and most populous continent, located primarily in the Eastern Hemisphere, Eastern and Northern Hemisphere, Northern Hemisphere of the Earth, Hemispheres. It shares the continental landmass of Eurasia with the cont ...

. Microbubbles-based contrast media is administrated
intravenously Intravenous therapy (abbreviated as IV therapy) is a medical technique that delivers fluids, medications and nutrition directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrition ...
into the
patient A patient is any recipient of health care Healthcare is the maintenance or improvement of health Health, according to the , is "a state of complete physical, and social and not merely the absence of and ".. (2006)''Constitution of the ...

blood stream The circulatory system, also called the cardiovascular system or the vascular system, is an organ system An organ system is a biological system A biological system is a complex network Network and networking may refer to: Arts, entertai ...
during the ultrasonography examination. Due to their size, the microbubbles remain confined in
blood vessels The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system An organ system is a biological system A biological system is a co ...

without extravasating towards the
interstitial fluid In cell biology Cell biology (also cellular biology or cytology) is a branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, ...
. An
ultrasound Ultrasound is s with higher than the upper audible limit of human . Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is appro ...

contrast media is therefore purely intravascular, making it an ideal agent to image
organ Organ may refer to: Biology * Organ (biology) In biology, an organ is a collection of Tissue (biology), tissues joined in a structural unit to serve a common function. In the biological organization , hierarchy of life, an organ lies betwee ...
microvascularization for
diagnostic Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic Logic is an interdisciplinary field which studies truth and reasoning. Inf ...
purposes. A typical clinical use of contrast ultrasonography is detection of a hypervascular
metastatic Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then, ...
tumor A neoplasm () is a type of abnormal and excessive growth of tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth ...

, which exhibits a contrast uptake (kinetics of microbubbles concentration in blood circulation) faster than healthy
biological tissue In biology, tissue is a Biological organisation#Levels, biological organizational level between cell (biology), cells and a complete organ (biology), organ. A tissue is an ensemble of similar cells and their extracellular matrix from the same o ...
surrounding the tumor. Other clinical applications using contrast exist, as in
echocardiography An echocardiography, echocardiogram, cardiac echo or simply an echo, is an of the . It is a type of of the heart, using standard ultrasound or . Echocardiography has become routinely used in the diagnosis, management, and follow-up of patients ...
to improve delineation of
left ventricle A ventricle is one of two large chambers toward the bottom of the heart The heart is a muscular MUSCULAR (DS-200B), located in the United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the Unite ...
for visualizing contractibility of
heart The heart is a muscular MUSCULAR (DS-200B), located in the United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,Usage is mixed. The Guardian' and Telegraph' use ...

muscle after a
myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory sy ...

. Finally, applications in quantitative perfusion (relative measurement of
blood flow Hemodynamics or haemodynamics are the dynamics Dynamics (from Greek language, Greek δυναμικός ''dynamikos'' "powerful", from δύναμις ''dynamis'' "power (disambiguation), power") or dynamic may refer to: Physics and engineering * ...

) have emerged for identifying early patient response to anti-cancerous drug treatment (methodology and clinical study by Dr Nathalie Lassau in 2011), enabling the best oncological
therapeutic A therapy or medical treatment (often abbreviated tx, Tx, or Tx) is the attempted remediation of a health Health is a state of physical, mental and social well-being Well-being, also known as ''wellness'', ''prudential value'' or ''quality ...
options to be determined. In oncological practice of medical contrast ultrasonography, clinicians use 'parametric imaging of vascular signatures' invented by Dr Nicolas Rognin in 2010. This method is conceived as a
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most often refers to: * Cell (biolo ...

aided diagnostic tool, facilitating characterization of a suspicious
tumor A neoplasm () is a type of abnormal and excessive growth of tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth ...

(
malignant Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign tumor, benign'' tumor in that a mali ...
versus
benign {{Unreferenced, date=June 2019, bot=noref (GreenC bot) Benignity (from Latin ''benignus'' "kind, good", itself deriving from ''bonus'' "good" and ''genus'' "origin") is any condition that is harmless in the long run. The opposite of benignity is ...
) in an organ. This method is based on medical
computational science Computational science, also known as scientific computing or scientific computation (SC), is a field that uses advanced computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes th ...
to analyze a time sequence of ultrasound contrast images, a digital video recorded in real-time during patient examination. Two consecutive
signal processing Signal processing is an electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronics, and electromagnetis ...

steps are applied to each
pixel In digital imaging Digital imaging or digital image acquisition is the creation of a representation of the visual characteristics of an object, such as a physical scene or the interior structure of an object. The term is often assumed to imp ...

of the tumor: #calculation of a vascular signature (contrast uptake difference with respect to healthy tissue surrounding the tumor); #automatic
classification Classification is a process related to categorization Categorization is the human ability and activity of recognizing shared features or similarities between the elements of the experience Experience refers to conscious , an English Paracels ...
of the vascular signature into a unique
parameter A parameter (), generally, is any characteristic that can help in defining or classifying a particular system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified wh ...

, the latter coded in one of the four following
color Color (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American Engli ...

s: #*
green Green is the color between blue and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 Nanometre, nm. In subtractive color systems, used in painting and color printing, it is created by ...

for continuous hyper-enhancement (contrast uptake higher than healthy tissue one), #*
blue Blue is one of the three primary colours of pigments in painting and traditional colour theory In the visual arts The visual arts are art forms such as painting Painting is the practice of applying paint Paint is any pig ...

for continuous hypo-enhancement (contrast uptake lower than healthy tissue one), #*
red Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength Image:dominant wavelength.png, frame, Dominant/complementary wavelength example on the CIE color ...

for fast hyper-enhancement (contrast uptake before healthy tissue one) or #*
yellow Yellow is the color between green and Orange (colour), orange on the Visible spectrum, spectrum of visible light. It is evoked by light with a dominant wavelength of roughly 575585 Nanometre, nm. It is a primary color in subtractive color syst ...

for fast hypo-enhancement (contrast uptake after healthy tissue one). Once
signal processing Signal processing is an electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronics, and electromagnetis ...

in each pixel is completed, a color spatial map of the parameter is displayed on a
computer monitor A computer monitor is an output device that displays information in pictorial or text form. A monitor usually comprises a electronic visual display, visual display, electronic circuit, some circuitry, a casing, and a power supply. The display de ...

, summarizing all
vascular The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an Biological system, organ system that permits blood to circulate and transport nutrien ...
information of the tumor in a single image called a parametric image (see last figure of press article as clinical examples). This parametric image is interpreted by clinicians based on predominant colorization of the tumor: red indicates a suspicion of
malignancy Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade ...
(risk of cancer), green or yellow – a high probability of
benignity {{Unreferenced, date=June 2019, bot=noref (GreenC bot) Benignity (from Latin ''benignus'' "kind, good", itself deriving from ''bonus'' "good" and ''genus'' "origin") is any condition that is harmless in the long run. The opposite of benignity is ...
. In the first case (suspicion of
malignant tumor Cancer is a group of diseases involving abnormal cell growth with the potential to invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible Cancer signs and symptoms, signs and ...
), the clinician typically prescribes a biopsy to confirm the diagnostic or a
CT scan A CT scan or computed tomography scan (formerly known as computed axial tomography or CAT scan) is a medical image, imaging Scientific technique, technique used in radiology to obtain detailed internal images of the body noninvasively for Diagno ...

examination as a second opinion. In the second case (quasi-certain of
benign tumor A benign tumor is a mass of cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Closed spaces * Monastic cell, a small room, hut, or cave in which a monk or religious recluse lives * P ...
), only a follow-up is needed with a contrast ultrasonography examination a few months later. The main clinical benefits are to avoid a systemic biopsy (with inherent risks of invasive procedures) of benign tumors or a
CT scan A CT scan or computed tomography scan (formerly known as computed axial tomography or CAT scan) is a medical image, imaging Scientific technique, technique used in radiology to obtain detailed internal images of the body noninvasively for Diagno ...

examination exposing the patient to
X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Moti ...

radiation. The parametric imaging of vascular signatures method proved to be effective in humans for characterization of tumors in the liver. In a
cancer screening Cancer screening aims to detect cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells ...
context, this method might be potentially applicable to other organs such as
breast The breast is one of two prominences located on the upper ventral Standard anatomical terms of location deal unambiguously with the of s, including s. Terms used generally derive from or roots and used to describe something in its . Th ...

or
prostate The prostate is both an accessory gland of the male reproductive system The male reproductive system consists of a number of sex organ A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual repr ...

.

## Molecular ultrasonography (ultrasound molecular imaging)

The current future of contrast ultrasonography is in
molecular imaging Molecular imaging is a field of medical imaging that focuses on imaging molecules of medical interest within living patients. This is in contrast to conventional methods for obtaining molecular information from preserved tissue samples, such as his ...
with potential clinical applications expected in
cancer screening Cancer screening aims to detect cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells ...
to detect
malignant tumor Cancer is a group of diseases involving abnormal cell growth with the potential to invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible Cancer signs and symptoms, signs and ...
s at their earliest stage of appearance. Molecular ultrasonography (or ultrasound molecular imaging) uses targeted microbubbles originally designed by Dr Alexander Klibanov in 1997; such targeted microbubbles specifically bind or adhere to tumoral microvessels by targeting biomolecular cancer expression (overexpression of certain biomolecules that occurs during Angiogenesis, neo-angiogenesis or inflammation in malignant tumors). As a result, a few minutes after their injection in blood circulation, the targeted microbubbles accumulate in the malignant tumor; facilitating its localization in a unique ultrasound contrast image. In 2013, the very first exploratory clinical trial in humans for prostate cancer was completed at Amsterdam in the Netherlands by Dr Hessel Wijkstra. In molecular ultrasonography, the technique of acoustic radiation force (also used for shear wave elastography) is applied in order to literally push the targeted microbubbles towards microvessels wall; first demonstrated by Dr Paul Dayton in 1999. This allows maximization of binding to the malignant tumor; the targeted microbubbles being in more direct contact with cancerous biomolecules expressed at the inner surface of tumoral microvessels. At the stage of scientific preclinical research, the technique of acoustic radiation force was implemented as a prototype in clinical ultrasound systems and validated ''in vivo'' in 2D and 3D imaging modes.

## Elastography (ultrasound elasticity imaging)

Ultrasound is also used for elastography, which is a relatively new imaging modality that maps the elastic properties of soft tissue. This modality emerged in the last two decades. Elastography is useful in medical diagnoses as it can discern healthy from unhealthy tissue for specific organs/growths. For example, cancerous tumors will often be harder than the surrounding tissue, and diseased livers are stiffer than healthy ones. There are many ultrasound elastography techniques.

## Interventional ultrasonography

Interventional ultrasonography involves biopsy, emptying fluids, intrauterine Blood transfusion (Hemolytic disease of the newborn). *Thyroid cysts: High frequency thyroid
ultrasound Ultrasound is s with higher than the upper audible limit of human . Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is appro ...

(HFUS) can be used to treat several gland conditions. The recurrent thyroid cyst that was usually treated in the past with surgery, can be treated effectively by a new procedure called percutaneous ethanol injection, or PEI. With ultrasound guided placement of a 25 gauge needle within the cyst, and after evacuation of the cyst fluid, about 50% of the cyst volume is injected back into the cavity, under strict operator visualization of the needle tip. The procedure is 80% successful in reducing the cyst to minute size. *Metastatic thyroid cancer neck lymph nodes: HFUS may also be used to treat metastatic thyroid cancer neck lymph nodes that occur in patients who either refuse, or are no longer candidates, for surgery. Small amounts of ethanol are injected under ultrasound guided needle placement. A power doppler blood flow study is done prior to injection. The blood flow can be destroyed and the node rendered inactive. Power doppler visualized blood flow can be eradicated, and there may be a drop in the cancer blood marker test, thyroglobulin, TG, as the node become non-functional. Another interventional use for HFUS is to mark a cancer node prior to surgery to help locate the node cluster at the surgery. A minute amount of methylene dye is injected, under careful ultrasound guided placement of the needle on the anterior surface, but not in the node. The dye will be evident to the thyroid surgeon when opening the neck. A similar localization procedure with methylene blue, can be done to locate parathyroid adenomas. *Joint injections can be guided by medical ultrasound, such as in ultrasound-guided hip joint injections.

## Compression ultrasonography

Compression ultrasonography is when the probe is pressed against the skin. This can bring the target structure closer to the probe, increasing spatial resolution of it. Comparison of the shape of the target structure before and after compression can aid in diagnosis. It is used in ultrasonography of deep venous thrombosis, wherein absence of vein compressibility is a strong indicator of thrombosis. Compression ultrasonography has both high sensitivity and specificity for detecting proximal deep vein thrombosis in symptomatic patients. Results are not reliable when the patient is asymptomatic, for example in high risk postoperative orthopedic patients. File:Ultrasonography of a normal appendix without and with compression.jpg, A normal appendix (anatomy), appendix without and with compression. Absence of compressibility indicates
appendicitis Appendicitis is inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a pr ...

. File:Ultrasonographic measurement of aortic diameter at the navel.svg, Compression is used in this ultrasonograph to get closer to the abdominal aorta, making the superior mesenteric vein and the
inferior vena cava The inferior vena cava is a large vein that carries the deoxygenated blood Blood is a body fluid Body fluids, bodily fluids, or biofluids are liquid A liquid is a nearly incompressible In fluid mechanics or more generally conti ...

look rather flat.

## Panoramic ultrasonography

Panoramic ultrasonography is the digital image stitching, stitching of multiple ultrasound images into a broader one. April 2010 It can display an entire abnormality and show its relationship to nearby structures on a single image.

# Attributes

As with all imaging modalities, ultrasonography has positive and negative attributes.

## Strengths

*
muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly cat ...

, soft tissue, and bone surfaces are imaged very well including the delineation of interfaces between solid and fluid-filled spaces. * "Live" images can be dynamically selected, permitting diagnosis and documentation often rapidly. Live images also permit ultrasound-guided biopsies or injections, which can be cumbersome with other imaging modalities. * Organ structure can be demonstrated. * There are no known long-term side effects when used according to guidelines, and discomfort is minimal. * Ability to image local variations in the mechanical properties of soft tissue. * Equipment is widely available and comparatively flexible. * Small, easily carried scanners are available which permit bedside examinations. * Transducers have become relatively inexpensive compared to other modes of investigation, such as CT scan, computed X-ray tomography, Dual energy X-ray absorptiometry, DEXA or magnetic resonance imaging. * Image resolution#Spatial resolution, Spatial resolution is better in high frequency ultrasound transducers than most other imaging modalities. * Use of an ultrasound research interface can offer a relatively inexpensive, real-time, and flexible method for capturing data required for specific research purposes of tissue characterization and development of new image processing techniques.

## Weaknesses

* Sonographic devices have trouble penetrating
bone A bone is a rigid tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa dubit ...

. For example, sonography of the adult brain is currently very limited. * Sonography performs very poorly when there is gas between the transducer and the organ of interest, due to the extreme differences in
acoustic impedance Acoustic impedance and specific acoustic impedance are measures of the opposition that a system presents to the acoustic flow resulting from an acoustic pressure applied to the system. The SI unit The International System of Units, known b ...
. For example, overlying gas in the gastrointestinal tract often makes ultrasound scanning of the
pancreas The pancreas is an Organ (anatomy), organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdominal cavity, abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine ...

difficult. Lung imaging however can be useful in demarcating pleural effusions, detecting heart failure and pneumonia. * Even in the absence of bone or air, the depth penetration of ultrasound may be limited depending on the frequency of imaging. Consequently, there might be difficulties imaging structures deep in the body, especially in obese patients. * Image quality and accuracy of diagnosis is limited with obese patients and overlying subcutaneous fat attenuates the sound beam. A lower frequency transducer is required with subsequent lower resolution. * The method is operator-dependent. Skill and experience is needed to acquire good-quality images and make accurate diagnoses. * There is no scout image as there is with CT and MRI. Once an image has been acquired there is no exact way to tell which part of the body was imaged. * 80% of sonographers suffer from Repetitive Strain Injuries (RSI) or so-called Work-Related Musculoskeletal Disorders (WMSD) because of bad ergonomic positions.

# Risks and side-effects

Ultrasonography is generally considered safe imaging, with the World Health Organizations stating: :"Diagnostic ultrasound is recognized as a safe, effective, and highly flexible imaging modality capable of providing clinically relevant information about most parts of the body in a rapid and cost-effective fashion". Diagnostic ultrasound studies of the fetus are generally considered to be safe during pregnancy. However, this diagnostic procedure should be performed only when there is a valid medical indication, and the lowest possible ultrasonic exposure setting should be used to gain the necessary diagnostic information under the "as low as reasonably practicable" or ALARP principle. Although there is no evidence that ultrasound could be harmful to the fetus, medical authorities typically strongly discourage the promotion, selling, or leasing of ultrasound equipment for making "keepsake fetal videos".

## Studies on the safety of ultrasound

* A meta-analysis of several ultrasonography studies published in 2000 found no statistically significant harmful effects from ultrasonography. It was noted that there is a lack of data on long-term substantive outcomes such as neurodevelopment. * A study at the Yale School of Medicine published in 2006 found a small but significant correlation between prolonged and frequent use of ultrasound and abnormal neuronal migration in mice. * A study performed in Sweden in 2001 has shown that subtle effects of neurological damage linked to ultrasound were implicated by an increased incidence in left-handedness in boys (a marker for brain problems when not hereditary) and speech delays. ** The above findings, however, were not confirmed in a follow-up study. ** A later study, however, performed on a larger sample of 8865 children, has established a statistically significant, albeit weak association of ultrasonography exposure and being non-right handed later in life.

# Regulation

Diagnostic and therapeutic ultrasound equipment is regulated in the US by the Food and Drug Administration, and worldwide by other national regulatory agencies. The FDA limits acoustic output using several metrics; generally, other agencies accept the FDA-established guidelines. Currently, New Mexico, Oregon, and North Dakota are the only US states that regulate diagnostic medical sonographers. Certification examinations for sonographers are available in the US from three organizations: the American Registry for Diagnostic Medical Sonography, Cardiovascular Credentialing International and the American Registry of Radiologic Technologists. The primary regulated metrics are Mechanical Index (MI), a metric associated with the cavitation bio-effect, and Thermal Index (TI) a metric associated with the tissue heating bio-effect. The FDA requires that the machine not exceed established limits, which are reasonably conservative in an effort to maintain diagnostic ultrasound as a safe imaging modality. This requires Industry self-regulation, self-regulation on the part of the manufacturer in terms of machine calibration. Ultrasound-based pre-natal care and sex screening technologies were launched in India in the 1980s. With concerns about its misuse for sex-selective abortion, the Government of India passed the Pre-Conception and Pre-Natal Diagnostic Techniques Act, 1994, Pre-natal Diagnostic Techniques Act (PNDT) in 1994 to distinguish and regulate legal and illegal uses of ultrasound equipment. The law was further amended as the Pre-Conception and Pre-natal Diagnostic Techniques (Regulation and Prevention of Misuse) (PCPNDT) Act in 2004 to deter and punish prenatal sex screening and sex selective abortion. It is currently illegal and a punishable crime in India to determine or disclose the sex of a fetus using ultrasound equipment.

# History

After the French physicist Pierre Curie’s discovery of piezoelectricity in 1880, ultrasonic waves could be deliberately generated for industry. In 1940, the American acoustical physicist Floyd Firestone devised the first ultrasonic echo imaging device, the Supersonic Reflectoscope, to detect internal flaws in metal castings. In 1941, Austrian neurologist Karl Theo Dussik, in collaboration with his brother, Friedrich, a physicist, was likely the first person to image the human body ultrasonically, outlining the ventricles of a human brain. Ultrasonic energy was first applied to the human body for medical purposes by Dr George Ludwig at the Naval Medical Research Institute, Bethesda, Maryland, in the late 1940s. English-born physicist John J. Wild, John Wild (1914–2009) first used ultrasound to assess the thickness of bowel tissue as early as 1949; he has been described as the "father of medical ultrasound". Subsequent advances took place concurrently in several countries but was not until 1961 when David Robinson and George Kossoff's work at the Australian Department of Health resulted in the first commercially practical water bath ultrasonic scanner. In 1963 Meyerdirk & Wright launched production of the first commercial, hand-held, articulated arm, compound contact B-mode scanner, which made ultrasound generally available for medical use.

## France

Léandre Pourcelot, a researcher and teacher at INSA (Institut National des Sciences Appliquées), Lyon, co-published a report in 1965 at the Académie des sciences, "''Effet Doppler et mesure du débit sanguin'' ("Doppler effect and measure of the blood flow"), the basis of his design of a Doppler flow meter in 1967.

## Scotland

Parallel developments in Glasgow, Scotland by Professor Ian Donald and colleagues at the Princess Royal Maternity Hospital, Glasgow Royal Maternity Hospital (GRMH) led to the first diagnostic applications of the technique. Donald was an obstetrics, obstetrician with a self-confessed "childish interest in machines, electronic and otherwise", who, having treated the wife of one of the company's directors, was invited to visit the Research Department of boilermakers Doosan Babcock, Babcock & Wilcox at Renfrew. He adapted their industrial ultrasound equipment to conduct experiments on various morbid anatomical specimens and assess their ultrasonic characteristics. Together with the medical physicist . and fellow obstetrician Dr John MacVicar, Donald refined the equipment to enable differentiation of pathology in live volunteer patients. These findings were reported in ''The Lancet'' on 7 June 1958 as "Investigation of Abdominal Masses by Pulsed Ultrasound" – possibly one of the most important papers published in the field of diagnostic
medical imaging Medical imaging is the technique and process of imaging Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of an image). Imaging technology is the application of materi ...
. At GRMH, Professor Donald and Dr James Willocks then refined their techniques to obstetric applications including fetal head measurement to assess the size and growth of the fetus. With the opening of the new Queen Mother's Hospital in Yorkhill in 1964, it became possible to improve these methods even further. Dr Stuart Campbell (Obstetrician and Gynaecologist), Stuart Campbell's pioneering work on fetal cephalometry led to it acquiring long-term status as the definitive method of study of foetal growth. As the technical quality of the scans was further developed, it soon became possible to study pregnancy from start to finish and diagnose its many complications such as multiple pregnancy, fetal abnormality and ''placenta praevia''. Diagnostic ultrasound has since been imported into practically every other area of medicine.

## Sweden

Medical ultrasonography was used in 1953 at Lund University by cardiology, cardiologist Inge Edler and Gustav Ludwig Hertz's son Carl Hellmuth Hertz, who was then a graduate student at the university's department of nuclear physics. Edler had asked Hertz if it was possible to use radar to look into the body, but Hertz said this was impossible. However, he said, it might be possible to use ultrasonography. Hertz was familiar with using ultrasonic reflectoscopes of the American acoustical physicist Floyd Firestone's invention for nondestructive testing, nondestructive materials testing, and together Edler and Hertz developed the idea of applying this methodology in medicine. The first successful measurement of heart activity was made on October 29, 1953, using a device borrowed from the ship construction company Kockums in Malmö. On December 16 the same year, the method was applied to generate an echo-encephalogram (ultrasonic probe of the
brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tis ...

). Edler and Hertz published their findings in 1954.

## United States

In 1962, after about two years of work, Joseph Holmes, William Wright, and Ralph Meyerdirk developed the first compound contact B-mode scanner. Their work had been supported by United States Public Health Service, U.S. Public Health Services and the University of Colorado Denver, University of Colorado. Wright and Meyerdirk left the university to form Physionic Engineering Inc., which launched the first commercial hand-held articulated arm compound contact B-mode scanner in 1963. This was the start of the most popular design in the history of ultrasound scanners. In the late 1960s Gene Strandness, Dr Gene Strandness and the bio-engineering group at the University of Washington conducted research on Doppler ultrasound as a diagnostic tool for vascular disease. Eventually, they developed technologies to use duplex imaging, or Doppler in conjunction with B-mode scanning, to view vascular structures in real time while also providing hemodynamic information. The first demonstration of color Doppler was by Geoff Stevenson, who was involved in the early developments and medical use of Doppler shifted ultrasonic energy.

# Manufacturers

The leading manufacturers of ultrasound equipment are Canon Medical
FUJIFILM SonoSite
GE Healthcare, Hitachi, Philips and Siemens Healthineers. Companies such as Usono design, develop, and sell accessories to make the use of ultrasound easier.

*
Doppler fetal monitor A Doppler fetal monitor is a hand-held ultrasound transducer used to detect the fetal heartbeat for prenatal care. It uses the Doppler effect to provide an audible simulation of the heart beat. Some models also display the heart rate in beats per ...
* Elastography * Polybiography * Radiographer * Ultrasound computer tomography * Ultrasound transmission tomography * 3D ultrasound