Interventional radiology (IR) is a medical specialty that performs various
minimally-invasive procedure
Minimally invasive procedures (also known as minimally invasive surgeries) encompass surgical techniques that limit the size of incisions needed, thereby reducing wound healing time, associated pain, and risk of infection. Surgery by definition ...
s using medical imaging guidance, such as
x-ray fluoroscopy,
computed tomography,
magnetic resonance imaging
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...
, or
ultrasound
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
. IR performs both diagnostic and therapeutic procedures
through very small incisions or
body orifice
A body orifice is any opening in the body of an animal.
External
In a typical mammalian body such as the human body, the external body orifices are:
* The nostrils, for breathing and the associated sense of smell
* The mouth, for eating, bre ...
s. Diagnostic IR procedures are those intended to help make a
diagnosis
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, analytics, and experience, to determine " cause and effect". In systems engin ...
or guide further medical treatment, and include image-guided biopsy of a tumor or injection of an
imaging contrast agent into a hollow structure, such as a
blood vessel
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away ...
or a
duct. By contrast,
therapeutic
A therapy or medical treatment (often abbreviated tx, Tx, or Tx) is the attempted remediation of a health problem, usually following a medical diagnosis.
As a rule, each therapy has indications and contraindications. There are many different ...
IR procedures provide direct treatment—they include catheter-based medicine delivery, medical device placement (e.g., stents), and angioplasty of narrowed structures.
The main benefits of interventional radiology techniques are that they can reach the deep structures of the body through a
body orifice
A body orifice is any opening in the body of an animal.
External
In a typical mammalian body such as the human body, the external body orifices are:
* The nostrils, for breathing and the associated sense of smell
* The mouth, for eating, bre ...
or tiny incision using
small needles and wires. That decreases risks, pain, and recovery compared to
open procedures.
Real-time
Real-time or real time describes various operations in computing or other processes that must guarantee response times within a specified time (deadline), usually a relatively short time. A real-time process is generally one that happens in defined ...
visualization also allows precision guidance to the abnormality, making the procedure or diagnosis more accurate. These benefits are weighed against the additional risks of lack of immediate access to internal structures (should bleeding or a perforation occur), and the risks of
radiation exposure such as cataracts and cancer.
Types of interventional radiology
Common elements
Interventional radiology is a set of techniques that allows access to the internal structures of the body through
body orifice
A body orifice is any opening in the body of an animal.
External
In a typical mammalian body such as the human body, the external body orifices are:
* The nostrils, for breathing and the associated sense of smell
* The mouth, for eating, bre ...
s or very small incisions and guidance with
medical imaging
Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to rev ...
. Regardless of the reason for the intervention, the procedure will likely use common elements such as a
puncture needle (to pass through the skin),
guidewires (to guide through structures such as blood vessels or the biliary or urinary systems), a sheath (which slides over the guidewire and hold the path open without injuring it), and
catheter
In medicine, a catheter (/ˈkæθətər/) is a thin tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgical procedure. Cath ...
s (that allow fluids to be pushed through them).
Also common to all intervention radiology procedures are the medical imaging machines that allow the healthcare provider to see what is occurring within the body. Some use x-rays (such as
CT and
fluoroscopy
Fluoroscopy () is an imaging technique that uses X-rays to obtain real-time moving images of the interior of an object. In its primary application of medical imaging, a fluoroscope () allows a physician to see the internal structure and functio ...
) and some do not (such as
ultrasound
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
and
MRI
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...
).
[ In each case, the images created may be modified by computer to better visualize the structures as is in the case with ]digital subtraction angiography
Digital subtraction angiography (DSA) is a fluoroscopy technique used in interventional radiology to clearly visualize blood vessels in a bony or dense soft tissue environment. Images are produced using contrast medium by subtracting a "pre-contra ...
, CT and MRI, or the display of the images improved with virtual reality
Virtual reality (VR) is a simulated experience that employs pose tracking and 3D near-eye displays to give the user an immersive feel of a virtual world. Applications of virtual reality include entertainment (particularly video games), educ ...
or augmented reality
Augmented reality (AR) is an interactive experience that combines the real world and computer-generated content. The content can span multiple sensory modalities, including visual, auditory, haptic, somatosensory and olfactory. AR can be de ...
presentation.
Diagnostic interventional radiology
* Angiography
Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is perfor ...
: Imaging the blood vessels to look for abnormalities with the use of various contrast media, including iodinated contrast, gadolinium based agents, and gas.
* Cholangiography
Cholangiography is the imaging of the bile duct (also known as the biliary tree) by x-rays and an injection of contrast medium.
__TOC__ Types
There are at least four types of cholangiography:
# Percutaneous transhepatic cholangiography (PTC): Exa ...
: Imaging the bile ducts within the liver to look for areas of blockage.
* Biopsy
A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a diseas ...
: Taking of a tissue sample from the area of interest for pathological examination from a percutaneous or transvenous approach.
Therapeutic interventional radiology
''Vascular''
* Balloon angioplasty/stent: Opening of narrow or blocked blood vessels using a balloon, with or without placement of metallic stents to aid in keep vessel patent.
* Endovascular aneurysm repair
Endovascular aneurysm repair (EVAR) is a type of minimally-invasive endovascular surgery used to treat pathology of the aorta, most commonly an abdominal aortic aneurysm (AAA). When used to treat thoracic aortic disease, the procedure is then spe ...
: Placement of endovascular stent-graft across an aneurysm
An aneurysm is an outward bulging, likened to a bubble or balloon, caused by a localized, abnormal, weak spot on a blood vessel wall. Aneurysms may be a result of a hereditary condition or an acquired disease. Aneurysms can also be a nidus (s ...
to prevent expansion or progression of the defective vessel.
* Embolization
Embolization refers to the passage and lodging of an embolus within the bloodstream. It may be of natural origin ( pathological), in which sense it is also called embolism, for example a pulmonary embolism; or it may be artificially indu ...
: Placement of a metallic coil or embolic substance (gel-foam, poly-vinyl alcohol) to block blood through to a blood vessel, either to stop bleeding or decrease blood flow to a target organ or tissue.
** Uterine artery embolization
Uterine artery embolization is a procedure in which an interventional radiologist uses a catheter to deliver small particles that block the blood supply to the uterine body. The procedure is done for the treatment of uterine fibroids and adenomyos ...
(UAE) or uterine fibroid embolization (UFE)
** Prostate artery embolization (PAE)
** Pulmonary arteriovenous malformation
Arteriovenous malformation is an abnormal connection between arteries and veins, bypassing the capillary system. This vascular anomaly is widely known because of its occurrence in the central nervous system (usually cerebral AVM), but can appe ...
(PAVM) embolization
* Thrombolysis
Thrombolysis, also called fibrinolytic therapy, is the breakdown (lysis) of blood clots formed in blood vessels, using medication. It is used in ST elevation myocardial infarction, stroke, and in cases of severe venous thromboembolism (massive ...
: Catheter-directed technique for dissolving blood clots, such as pulmonary embolism and deep venous thrombosis, with either pharmaceutical (TPA) or mechanical means.
* IVC filters: Metallic filters placed in the vena cava to prevent propagation of deep venous thrombus.
* Dialysis related interventions: Placement of tunneled hemodialysis catheters, peritoneal dialysis catheters, and revision/thrombolysis of poorly functioning surgically placed AV fistulas and grafts.
* TIPS: Placement of a Transjugular Intrahepatic Porto-systemic Shunt (TIPS) for select indications in patients with critical end-stage liver disease and portal hypertension.
* Endovenous laser treatment
Endovenous laser treatment (ELT) is a minimally invasive ultrasound-guided technique used for treating varicose veins using laser energy commonly performed by a phlebologist, interventional radiologist or vascular surgeon.
Methods
Endovenous las ...
of varicose veins: Placement of thin laser fiber in varicose veins for non-surgical treatment of venous insufficiency.
'' Biliary intervention''
* Placement of catheters in the biliary system to bypass biliary obstructions and decompress the biliary system.
* Placement of permanent indwelling biliary stents.
* Cholecystostomy
A cholecystostomy or cholecystotomy is a procedure where a stoma is created in the gallbladder, which can facilitate placement of a tube for drainage, first performed by American surgeon, Dr. John Stough Bobbs, in 1867. It is sometimes used in cas ...
: Placement of a tube into the gallbladder to remove infected bile in patients with cholecystitis, an inflammation of the gallbladder, who are too frail or too sick to undergo surgery.
''Catheter placement''
* Central venous catheter
A central venous catheter (CVC), also known as a central line(c-line), central venous line, or central venous access catheter, is a catheter placed into a large vein. It is a form of venous access. Placement of larger catheters in more central ...
placement: Vascular access and management of intravenous
Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrie ...
devices (IVs), including both tunneled and non-tunneled catheters (e.g., PIC, Hickman
Hickman or Hickmann may refer to:
People
* Hickman (surname), notable people with the surname Hickman or Hickmann
* Hickman Ewing, American attorney
* Hickman Price (1911–1989), assistant secretary in the United States Department of Commerce
* ...
, port catheters, hemodialysis catheters, translumbar and transhepatic venous lines).
* Drainage catheter placement: Placement of tubes to drain pathologic fluid collections (e.g., abscess, pleural effusion). This may be achieved by percutaneous, trans-rectal, or trans-vaginal approach. Exchange or repositioning of indwelling catheters is achieved over a guidewire under image guidance.
* Radiologically inserted gastrostomy or jejunostomy : Placement of a feeding tube percutaneously into the stomach and/or jejunum.
''Ablative''
* Chemoembolization
Transcatheter arterial chemoembolization (TACE) is a minimally invasive procedure performed in interventional radiology to restrict a tumor's blood supply. Small embolic particles coated with chemotherapeutic drugs are injected selectively through ...
: Combined injection of chemotherapy and embolic agents into the arterial blood supply of a tumor, with the goal of both local administration of chemotherapy, slowing "washout" of the chemotherapy drug, and also decreasing tumor arterial supply
* Radioembolization
Selective internal radiation therapy (SIRT), also known as transarterial radioembolization (TARE), radioembolization or intra-arterial microbrachytherapy is a form of radiation therapy used in interventional radiology to treat cancer. It is general ...
: Combined injection of radioactive glass or plastic beads and embolic agents into the arterial blood supply of a tumor, with the goal of both local administration of radiotherapy, slowing "washout" of the radioactive substance, and also decreasing tumor arterial supply
* Radiofrequency ablation
Radiofrequency ablation (RFA), also called fulguration, is a medical procedure in which part of the electrical conduction system of the heart, tumor or other dysfunctional tissue is ablated using the heat generated from medium frequency alternati ...
(RF/RFA): Local treatment in which a special catheter destroys tissue with heat generated by medium frequency alternating currents
* Cryoablation
Cryoablation is a process that uses extreme cold to destroy tissue. Cryoablation is performed using hollow needles (cryoprobes) through which cooled, thermally conductive, fluids are circulated. Cryoprobes are positioned adjacent to the target in ...
: Local treatment with a special catheter that destroys tissue with cold temperature generated by rapid expansion of compressed argon
Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abu ...
gas—used mostly to treat small renal cancers and for the palliation of painful bone lesions
* Microwave ablation: Local treatment with a special catheter that destroys tissue with heat generated by microwave
Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ran ...
s
''Genitourinary''
* Percutaneous nephrostomy {{More citations needed, date=January 2021
In surgery, a percutaneous procedurei.e. Granger et al., 2012 is any medical procedure or method where access to inner organs or other tissue is done via needle-puncture of the skin, rather than by using ...
or nephroureteral stent placement: Placement of a catheter through the skin, directly into the kidney to drain from the collecting system. This is typically done to treat a downstream obstruction of urine.
* Ureteral stent exchange: indwelling double-J type ureteral stents, typically placed by urologist using cystoscopy, may be exchanged in retrograde fashion through the female urethra. The IR uses a thin wire snare under fluoroscopy to capture the distal portion of the stent. After partially extracting the distalmost stent, exchange for a new stent can be accomplished over a guidewire.
Techniques for specific disorders
Gastrointestinal intervention
Gastrointestinal hemorrhage
The treatment of gastrointestinal hemorrhage
Gastrointestinal bleeding (GI bleed), also called gastrointestinal hemorrhage (GIB), is all forms of bleeding in the gastrointestinal tract, from the mouth to the rectum. When there is significant blood loss over a short time, symptoms may includ ...
can range anywhere from monitoring an asymptomatic bleed to supporting and maintaining the hemodynamic function of the patient. The role for the interventional radiologist is to offer patients an image-guided, minimally invasive procedure to alleviate a condition that could be otherwise be potentially life-threatening.
The avenue for the interventional radiologist to dictate the clinical course of a GI bleed is largely influenced by location of bleed, overall patient health and other conditions the patient may have, most notably heart and liver functions. For most cases, collaboration between the gastroenterologist and interventional radiologist optimizes patient outcome but again, is largely dictated by anatomical location of the GI bleed. If a patient is evaluated and determined to be a candidate for an interventional procedure, then the bleed is often treated by embolization. Embolization is a process in which the interventional radiologist accesses the culprit bleeding vessel via a small catheter and interrupts blood flow to the site of bleeding via various mechanisms. Side effects of this procedure are minimal but there is a risk of bleeding and infection—though much less than the equivalent surgical procedure. When successful, the procedure often eliminates the bleed and patients can walk after a few hours of rest.
Hepatobiliary intervention
Transjugular intrahepatic portosystemic shunt
A transjugular intrahepatic portosystemic shunt (TIPS) is a procedure an interventional radiologist performs to create a shunt (essentially, a new conduit allowing for blood flow) between the hepatic inferior vena cava and the portal vein, a vessel that returns blood from the intestines to the liver. The portal vein is the site where hypertension (high blood pressure) can produce a myriad of deleterious effects throughout the liver and small or large intestine.
Primarily, a TIPS functions to alleviate two different conditions: an emergent/life-threatening GI bleed or ascites (excessive abdominal fluid) caused by too high of blood pressure in the portal vein that is otherwise uncontrolled by diet and medications.
The workup for the procedure is straightforward and the interventional radiologist performing the procedure often orders several tests to assess how well the patient will tolerate the procedure. These are often simple blood tests, and an ultrasound of the heart and liver. The procedure is often well tolerated and can result in a permanent reduction or elimination of symptoms. The procedure can take anywhere between 15 minutes to an hour and has lower risks of bleeding or infection compared to an equivalent surgical procedure.
A TIPS may cause temporary confusion or worsening of liver/heart function. The degree of these two side effects largely depend on the health of the patient's heart and liver prior to the procedure and the risk-benefits of the procedure must be thoroughly discussed with their interventional radiologist before beginning. If the post-procedural consequences are more troublesome to the patient than their initial symptoms the artificial conduit created by the procedure can be reversed if the post-procedural side effects outweigh those caused by the prior conditions.
Biliary intervention
In addition to normal liver tissue, the liver has three main vessels traversing it: arteries, veins and bile ducts. While bile is made in the liver and stored in the gallbladder, the bile eventually passes into the GI tract through the hepatic, cystic and common bile ducts. Any condition that prevents the normal flow of bile from the liver, through these bile vessels and into the GI tract can cause a condition called jaundice
Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme meta ...
.
While jaundice can be caused by a few viruses that the human body can naturally clear, jaundice in the setting of an obstruction is usually caused by a cancer and can result in intolerable itching and a worsening of liver function that can be life-threatening. Depending on a patient's condition, this type of obstructive jaundice can be alleviated with surgery or chemotherapy but if these measures fail to restore proper flow of bile, an interventional radiologist can perform a procedure called a percutaneous transhepatic cholangiography (PTC).
A PTC is an outpatient procedure lasting anywhere from 15 minutes to an hour where an interventional radiologist accesses the patient's bile duct system with a needle through the skin and liver under imaging guidance. Using fluoroscopy (essentially an Xray camera) to guide a wire (followed by a catheter over the wire) through the bile duct system and into the GI tract, essentially restoring the normal flow of bile. If the patient's GI tract cannot be accessed due to the obstruction, the catheter can be placed to drain the bile duct system into a bag that the patient can wear during daily activities. Risks of this procedure include bleeding and infection but these are much lower than an equivalent surgical procedure.
Genitourinary intervention
Benign prostatic hyperplasia
Benign prostatic hyperplasia
Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the prostate gland. Symptoms may include frequent urination, trouble starting to urinate, weak stream, inability to urinate, or loss o ...
, or BPH, is a noncancerous condition that commonly affects men over the age of 50. The prostate gland enlarges and compresses the adjacent urethra, making it difficult for men to control frequency and/or urgency of urination. First line therapy involves medication, though long-term treatment for symptoms that are persistent despite medical optimization typically involves transurethral resection of the prostate (TURP) as the "gold standard" of care. However, TURP can lead to urinary incontinence or permanent male infertility and may not be the ideal procedure for a certain subset of patients. For those reasons, a physician may recommend undergoing a treatment known as prostate artery embolization (PAE).
Patients typically go home the same day as the procedure and can expect to feel some symptom relief in a matter of days. Though rare, risks of PAE include unintentional embolization of nearby blood vessels, which can result in loss of blood flow to surrounding areas of the bladder or rectum.
Data suggests that TURP may have higher rates of symptom resolution at 1 and 6 months, but PAE appears to provide lower risks of complications more commonly associated with surgery, such as infection.
Kidney stone disease
Kidney stones
Kidney stone disease, also known as nephrolithiasis or urolithiasis, is a crystallopathy where 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 s ...
can be present along any part of the course of the urinary tract from the kidneys to the urethra. The most common symptoms, whether in men or women, are sudden onset, intense flank pain accompanied by blood in the urine. Most kidney stones pass spontaneously, but larger ones (greater than 5 mm) are less likely to, and can cause severe pain or infection.
The interventional radiologist plays a large clinical role in the treatment of kidney stones that are unlikely to pass on their own. The gold standard of treatment for these types of stones is surgical removal. However, some patients have an infected stone and are simply too ill for an operative surgical removal. In these instances, the mainstay of IR treatment is a percutaneous nephrostomy tube. This is a procedure where a small caliber catheter is placed through the skin and into the urinary collecting system upstream of the stone. This procedure not only drains any infection, often bringing about a precipitous improvement in the patient's symptoms but also diverts urine—thus giving the patient more time to recover before definitive surgical treatment.
Varicocele
A varicocele
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 vessels originate in the abdomen and course down through the inguinal canal as p ...
is defined as an enlargement of the veins within the scrotum, most commonly occurring on the left side due to anatomical reasons. When this happens, blood can stagnate within these dilated veins and cause temperature fluctuations within the testicle itself. The exact cause to this condition remains unknown and an ill-favored sequela can be male infertility
Infertility is the inability of a person, animal or plant to reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species (mostly haplodiploid insects). It is the normal state ...
.
The mainstay of treatment for this condition within the field of interventional radiology is varicocele embolization. An embolization, within the context of this procedure, results in the interruption of venous blood flow. The interruption of blood flow abates venous dilation of blood that can lead to impaired testicular temperature regulation and theoretically improve infertility. The physician accesses the dilated scrotal veins with a small catheter via a vein in the groin and embolize the varicocele. Patients often tolerate this procedure well and are able to return home the same day.
Neurological intervention
Acute ischemic stroke
About 87% of all strokes are ischemic strokes, in which blood flow to the brain is blocked. A clot-busting medication such as tissue plasminogen activator
Tissue plasminogen activator (abbreviated tPA or PLAT) is a protein involved in the breakdown of blood clots. It is a serine protease () found on endothelial cells, the cells that line the blood vessels. As an enzyme, it catalyzes the conversion ...
(t-PA) can be used in a controlled hospital setting to dissolve the clot and help restore blood flow to the damaged area of the brain. Certain patients with an acute ischemic stroke may be candidates for endovascular therapy. Endovascular therapy is a procedure performed by neurointerventionalists to remove or dissolve the thrombus
A thrombus (plural thrombi), colloquially called a blood clot, is the final product of the blood coagulation step in hemostasis. There are two components to a thrombus: aggregated platelets and red blood cells that form a plug, and a mesh of ...
(clot) and restore blood flow to parts of the brain. Using a catheter that is directed through the blood vessels in the arm or leg up to the brain, the interventionalist can remove the thrombus or deliver drugs to dissolve the thrombus.[ These procedures are referred to as mechanical thrombectomy or ]thrombolysis
Thrombolysis, also called fibrinolytic therapy, is the breakdown (lysis) of blood clots formed in blood vessels, using medication. It is used in ST elevation myocardial infarction, stroke, and in cases of severe venous thromboembolism (massive ...
, and several factors are considered before the procedure is completed.
People who may be eligible for endovascular treatment have a ''large vessel occlusion'', which means the thrombus is in an artery that is large enough to reach and there are no contraindications such as, a hemorrhagic stroke (bleeding in the brain), greater than six hours since onset of symptoms, or greater than 24 hours in special cases. Hospitals with comprehensive stroke centers are equipped to treat patients with endovascular care.
Long-term care after an ischemic stroke is focused on rehabilitation and preventing future blood clots using anticoagulant therapy. Patients work with specialists from fields such as physical therapy, occupational therapy
Occupational therapy (OT) is a global healthcare profession. It involves the use of assessment and intervention to develop, recover, or maintain the meaningful activities, or ''occupations'', of individuals, groups, or communities. The field of ...
, and speech therapy to complete recovery.
Intracranial aneurysm
Although there are no clearly defined recommendations on treatment of asymptomatic aneurysms, all symptomatic unruptured brain aneurysms should be treated. Endovascular therapy is an effective treatment for select cases. During this treatment, an interventional radiologist inserts a catheter into the patient's leg and uses it to guide a coil through blood vessels to the site of the aneurysm. The coil induces clotting within the aneurysm, which reduces the risk of rupture. Multiple coils may be used depending on the size. Imaging studies ( DSA, CTA, or MRA) help characterize the aneurysm to decide the best course of treatment, whether endovascular coiling or surgical clipping. Endovascular coiling is associated with a reduction in procedural morbidity and mortality over surgical. For cases of ruptured aneurysms, emergent treatment is based on the type of aneurysm, and may use a combination of techniques. Conservative therapy focuses on minimizing modifiable risk factors with blood pressure control and smoking cessation.
Cerebral arteriovenous malformation
Arteriovenous malformations (AVMs) are abnormal blood vessel structures in which an artery connects to a vein via an abnormal channel. This creates a high flow system that puts the vessel at risk of rupture. Ruptured AVMs require emergency management of the patient; unruptured AVMs require expert consultation to discuss the risks and benefits of treatment. Current treatment options include conservative management, surgical resection, stereotactic radiosurgery, endovascular embolization, or combinations of these treatments. Endovascular embolization
Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs bo ...
is a technique used by neurointerventionalists in which particles, glue, or coils are lodged inside the AVM to prevent blood flow through the abnormal channel. During this treatment, an interventional radiologist guides a catheter through a blood vessel accessed from the patient's leg to the site of the AVM. The particles, glue, or coils induce clotting within the malformation, which reduces the risk of rupture.
Pain management
Joint and local injections
Utilizing image guidance, local anesthetics and/or long-acting steroid medications can be directly delivered to localized sites of pain. The use of image guidance helps to confirm appropriate needle placement. This includes common imaging modalities used in joint injections: ultrasound
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
, fluoroscopy
Fluoroscopy () is an imaging technique that uses X-rays to obtain real-time moving images of the interior of an object. In its primary application of medical imaging, a fluoroscope () allows a physician to see the internal structure and functio ...
and computerized tomography (CT).
= Facet joints
=
* Facet joints
Facets () are flat faces on geometric shapes. The organization of naturally occurring facets was key to early developments in crystallography, since they reflect the underlying symmetry of the crystal structure. Gemstones commonly have facets cut ...
, also known as zygapophyseal joints, refer to small bony structures located between the vertebrae of the spine that promote spinal stability.
* Degeneration or damage to the facet joints can often lead to '' facet joint syndrome'', which can be both diagnosed and treated by image-guided injection of anesthetics.
* Facet joint block is a minimally invasive procedure
Minimally invasive procedures (also known as minimally invasive surgeries) encompass surgical techniques that limit the size of incisions needed, thereby reducing wound healing time, associated pain, and risk of infection. Surgery by definition ...
in which a physician uses fluoroscopy
Fluoroscopy () is an imaging technique that uses X-rays to obtain real-time moving images of the interior of an object. In its primary application of medical imaging, a fluoroscope () allows a physician to see the internal structure and functio ...
or CT imaging to guide the placement of an injection of medication into a facet joint to provide pain relief.
= Sacroiliac joints
=
* The sacroiliac joint
The sacroiliac joint or SI joint (SIJ) is the joint between the sacrum and the ilium bones of the pelvis, which are connected by strong ligaments. In humans, the sacrum supports the spine and is supported in turn by an ilium on each side. Th ...
is a structure that is located at the bottom of the spine, and connects the spine to hips. The purpose of this joint is to help the spine bear the weight of the upper region of the body. The sacroiliac joint also decreases the incidence of injuries by improving overall stability and restricting the torso's range of movement.
* A sacroiliac joint injection is typically performed to decrease persistent back pain that developed due to an injured or inflamed sacroiliac joint.
= Epidural space
=
* In the spine, the epidural space
In anatomy, the epidural space is the potential space between the dura mater and vertebrae (spine).
The anatomy term "epidural space" has its origin in the Ancient Greek language; , "on, upon" + dura mater also known as "epidural cavity", "e ...
is an anatomic space {{set index article
In anatomy, a spatium or anatomic space is a space (cavity or gap). Anatomic spaces are often landmarks to find other important structures. When they fill with gases (such as air) or liquids (such as blood) in pathological ways, ...
that is the outermost part of the spinal canal. It is the space within the canal (formed by the surrounding vertebrae
The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...
) lying outside the dura mater
In neuroanatomy, dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. ...
(which encloses the arachnoid mater
The arachnoid mater (or simply arachnoid) is one of the three meninges, the protective membranes that cover the brain and spinal cord. It is so named because of its resemblance to a spider web. The arachnoid mater is a derivative of the neural c ...
, subarachnoid space, the cerebrospinal fluid
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates.
CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...
, and the spinal cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spi ...
).
* Injection of local anesthetics is often performed to treat local pain or radiculopathy
Radiculopathy, also commonly referred to as pinched nerve, refers to a set of conditions in which one or more nerves are affected and do not work properly (a neuropathy). Radiculopathy can result in pain (radicular pain), weakness, altered sens ...
, particularly due to disc herniation
Spinal disc herniation is an injury to the cushioning and connective tissue between vertebrae, usually caused by excessive strain or trauma to the spine. It may result in back pain, pain or sensation in different parts of the body, and physical ...
or central/foraminal stenosis.
* Usually performed under fluoroscopic guidance.
= Selective nerve root injection
=
* A spinal nerve root Spinal nerve root may refer to:
* Posterior root of spinal nerve
* Anterior root of spinal nerve
In anatomy and neurology, the ventral root of spinal nerve, anterior root, or motor root is the efferent motor root of a spinal nerve.
At its dist ...
is the initial or proximal segment of one of the thirty-one pairs of spinal nerves
A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the ...
leaving the central nervous system from the spinal cord.
* Damage to nerve roots can cause paresis
In medicine, paresis () is a condition typified by a weakness of voluntary movement, or by partial loss of voluntary movement or by impaired movement. When used without qualifiers, it usually refers to the limbs, but it can also be used to desc ...
and paralysis of the muscle innervated by the affected spinal nerve. It can also cause pain and numbness in the corresponding dermatome Dermatome may refer to:
* Dermatome (anatomy), an area of skin that is supplied by a single pair of dorsal roots
* Dermatome (embryology), the portion of the embryonic paraxial mesoderm, the somite, which gives rise to dermis
* Dermatome (instrument ...
. A common cause of damage to the nerve roots are lesions in the spine, such as prolapse of the nucleus pulposus, spinal tuberculosis
Pott disease is tuberculosis of the spine, usually due to haematogenous spread from other sites, often the lungs. The lower thoracic and upper lumbar vertebrae areas of the spine are most often affected.
It causes a kind of tuberculous arthriti ...
, 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 tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
, 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 protective response involving im ...
and spinal tabes. Root pain syndromes, known colloquially as radiculitis
Radicular pain, or radiculitis, is pain "radiated" along the dermatome (sensory distribution) of a nerve due to inflammation or other irritation of the nerve root (radiculopathy) at its connection to the spinal column. A common form of radicu ...
(i.e., sciatica
Sciatica is pain going down the leg from the lower back. This pain may go down the back, outside, or front of the leg. Onset is often sudden following activities like heavy lifting, though gradual onset may also occur. The pain is often described ...
) are one of the most common symptoms caused by damage to the nerve root.
* Used to treat patients with radicular symptoms in the cervical, thoracic, lumbar or sacral region.
* Helps to alleviate pain by dealing with inflammation of the nerve root.
Chronic pelvic pain
* Veins
Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...
have one-way valves that help blood flow toward the heart. If the valves are weak or damaged, blood can pool in veins, making them swell. When this happens near the pelvis, it is called pelvic congestion syndrome
Pelvic congestion syndrome, also known as pelvic vein incompetence, is a long term condition believed to be due to enlarged veins in the lower abdomen. The condition may cause chronic pain, such as a constant dull ache, which can be worsened by ...
, which can lead to chronic pain
Chronic pain is classified as pain that lasts longer than three to six months. In medicine, the distinction between Acute (medicine), acute and Chronic condition, chronic pain is sometimes determined by the amount of time since onset. Two commonly ...
beneath the level of the belly button.
* Pelvic congestion syndrome
Pelvic congestion syndrome, also known as pelvic vein incompetence, is a long term condition believed to be due to enlarged veins in the lower abdomen. The condition may cause chronic pain, such as a constant dull ache, which can be worsened by ...
usually affects women who have previously been pregnant, because the ovarian veins and pelvic veins had widened to accommodate the increased blood flow from the uterus
The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The uter ...
during pregnancy. After the pregnancy, some of these veins remain enlarged and fail to return to their previous size, causing them to weaken and allowing blood to pool.
* An interventional radiologist
Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs bo ...
can offer a minimally invasive treatment option for pelvic congestion syndrome: ovarian vein embolization
* Ovarian vein embolization is a same-day treatment, which takes place in an interventional radiology suite. The interventional radiologist gains access through a large vein in the groin, called the femoral vein
In the human body, the femoral vein is a blood vessel that accompanies the femoral artery in the femoral sheath. It begins at the adductor hiatus (an opening in the adductor magnus muscle) as the continuation of the popliteal vein. It ends a ...
, by using a small catheter
In medicine, a catheter (/ˈkæθətər/) is a thin tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgical procedure. Cath ...
, which is a flexible tube like a strand of spaghetti. The catheter is moved through the vein to the enlarged pelvic veins, allowing the introduction of embolic agents, which are medications that cause the vein to seal off and relieve the painful pressure.
** This treatment can be less expensive than surgery and is much less invasive.
* A number of diagnostic tests
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, diagnostic imaging, genetic te ...
can be performed through minimally invasive methods, to determine whether a patient's chronic pelvic pain
Pelvic pain is pain in the area of the pelvis. Acute pain is more common than chronic pain. If the pain lasts for more than six months, it is deemed to be chronic pelvic pain. It can affect both the male and female pelvis.
Common causes in inclu ...
is a result of pelvic varicose veins. These tests include:
** Pelvic and Transvaginal Ultrasound
** Pelvic Venogram
** Computed Tomography (CT)
** Magnetic Resonance Imaging (MRI)
Palliative care
* Palliative care
Palliative care (derived from the Latin root , or 'to cloak') is an interdisciplinary medical caregiving approach aimed at optimizing quality of life and mitigating suffering among people with serious, complex, and often terminal illnesses. Wit ...
is an interdisciplinary approach to specialized medical and nursing care for people with life-limiting illnesses. It focuses on providing relief from the symptoms, pain, physical stress, and mental stress at any stage of illness. The goal is to improve quality of life for both the person and their family.
* The interventional radiologist
Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs bo ...
may be uniquely skilled as hospice
Hospice care is a type of health care that focuses on the palliation of a terminally ill patient's pain and symptoms and attending to their emotional and spiritual needs at the end of life. Hospice care prioritizes comfort and quality of life by ...
and palliative medicine
In 2006, ''hospice and palliative medicine'' was officially recognized by the American Board of Medical Specialties, and is ''co-sponsored'' by the American Boards of
* Internal Medicine
* Anesthesiology
* Family Medicine
* Physical Medicine ...
providers. As an imager, the radiologist
Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiat ...
is the expert in obtaining maximum imaging value; furthermore, the radiologist
Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiat ...
has extensive experience in diagnostic image interpretation and disease prognostication. In addition, the interventional radiologist
Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs bo ...
has an array of both therapeutic and palliative interventions to offer the patient coping with a life-threatening illness.
Nerve block/ablations
* Injection of medication or anesthetic to decrease inflammation or "turn off" a pain signal along a specific distribution of nerve.
* "Block
Block or blocked may refer to:
Arts, entertainment and media Broadcasting
* Block programming, the result of a programming strategy in broadcasting
* W242BX, a radio station licensed to Greenville, South Carolina, United States known as ''96.3 ...
" vs. Ablation": Although these terms are often used interchangeably, they differ in terms of duration of action
** Nerve block: "temporary disruption of the disruption of pain transmission via the celiac plexus and is accomplished by injecting corticosteroids or long-acting local anesthetics".
** Neurolysis: "permanent destruction of the celiac plexus with ethanol or phenol".
* Types of blocks/neurolyses:
** Celiac plexus block/neurolysis: A procedure performed to manage refractory cancer-related abdominal pain by modulating the celiac plexus
The celiac plexus, also known as the solar plexus because of its radiating nerve fibers, is a complex network of nerves located in the abdomen, near where the celiac trunk, superior mesenteric artery, and renal arteries branch from the abdomi ...
, which is a network of nerve fibers
A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system.
A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the e ...
located in the retroperitoneum
The retroperitoneal space (retroperitoneum) is the anatomical space (sometimes a potential space) behind (''retro'') the peritoneum. It has no specific delineating anatomical structures. Organs are retroperitoneal if they have peritoneum on their ...
along the anterolateral wall of the aorta
The aorta ( ) is the main and largest artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries). The aorta distributes ...
.
*** Often used in the management of incurable pancreatic cancer
Pancreatic cancer arises when cell (biology), cells in the pancreas, a glandular organ behind the stomach, begin to multiply out of control and form a Neoplasm, mass. These cancerous cells have the malignant, ability to invade other parts of t ...
.
*** Often utilizes multidetector CT for image guidance.
** Superior hypogastric plexus block/neurolysis: A procedure performed to manage refractory abdominal/pelvis pain by modulating the superior hypogastric plexus
The superior hypogastric plexus (in older texts, hypogastric plexus or presacral nerve) is a plexus of nerves situated on the vertebral bodies anterior to the bifurcation of the abdominal aorta.
Structure
From the plexus, sympathetic fibers are ca ...
, which is a network of nerve fibers located in the retroperitoneum that modulate pain from the bladder
The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...
, vulva
The vulva (plural: vulvas or vulvae; derived from Latin for wrapper or covering) consists of the external sex organ, female sex organs. The vulva includes the mons pubis (or mons veneris), labia majora, labia minora, clitoris, bulb of vestibu ...
, vagina
In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen ...
, uterus
The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The uter ...
, urethra
The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra con ...
, penis
A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during copulation. Such organs occur in many animals, both vertebrate and invertebrate, but males do n ...
, perineum
The perineum in humans is the space between the anus and scrotum in the male, or between the anus and the vulva in the female. The perineum is the region of the body between the pubic symphysis (pubic arch) and the coccyx (tail bone), includi ...
, prostate
The prostate is both an Male accessory gland, accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, ...
, testes
A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoster ...
, rectum
The rectum is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the s ...
, and colon.
** Lumbar sympathetic block: A procedure performed to manage pain originating from the lower back, buttocks
The buttocks (singular: buttock) are two rounded portions of the exterior anatomy of most mammals, located on the posterior of the pelvic region. In humans, the buttocks are located between the lower back and the perineum. They are composed ...
or legs
A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element ...
.
*** Common indications: complex regional pain syndrome (CRPS)/regional sympathetic dystrophy (RDS), post-herpetic neuralgia, neuropathy
Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or o ...
.
** Pudendal nerve block: A procedure performed to manage chronic pelvic pain
Pelvic pain is pain in the area of the pelvis. Acute pain is more common than chronic pain. If the pain lasts for more than six months, it is deemed to be chronic pelvic pain. It can affect both the male and female pelvis.
Common causes in inclu ...
.
*** Common indications: pudendal neuralgia
Pudendal nerve entrapment (PNE), also known as Alcock canal syndrome, is an uncommon source of chronic pain in which the pudendal nerve (located in the pelvis) is entrapped or compressed in Alcock's canal. There are several different types of ...
(i.e., repetitive use from cycling), cancer-related pain
** Sphenopalatine ganglion block
*** A procedure performed to manage head and neck pain/headaches related to the trigeminal nerve
In neuroanatomy, the trigeminal nerve ( lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chewin ...
, usually in the treatment of migraine headaches.
Palliative bone/musculoskeletal
* The standard of care for local treatment of extraspinal osseous metastases is external-beam radiation therapy. Fifty percent of patients who undergo this therapy achieve complete response or resolution of symptoms. Of the remaining patients, half fail therapy (20–30% of the total), 10% require retreatment, and 1–3% experience debilitating complications such as fracture of the treated bone.
* Due to the need for multiple treatments requiring multiple transports to and from the hospital and potential disruption to treatment/therapy, minimally invasive
Minimally invasive procedures (also known as minimally invasive surgeries) encompass Surgery, surgical techniques that limit the size of incisions needed, thereby reducing wound healing time, associated pain, and risk of infection. Surgery by d ...
options in the treatment of extraspinal osseous metastases have emerged as attractive options in management of symptomatic metastases. These typically take the form of three types of ablative therapy: microwave thermal ablation, radiofrequency ablation
Radiofrequency ablation (RFA), also called fulguration, is a medical procedure in which part of the electrical conduction system of the heart, tumor or other dysfunctional tissue is ablated using the heat generated from medium frequency alternati ...
("coblation") and cryoablation
Cryoablation is a process that uses extreme cold to destroy tissue. Cryoablation is performed using hollow needles (cryoprobes) through which cooled, thermally conductive, fluids are circulated. Cryoprobes are positioned adjacent to the target in ...
.
** Microwave thermal ablation
*** Microwave ablation is a treatment that uses heat to treat tumors. An interventional radiologist
Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs bo ...
makes a tiny incision in the skin to insert a special needle into the body. Using a live computed tomography (CT) scan or an ultrasound
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
, the doctor guides the needle to the tumor. The interventional radiologist
Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs bo ...
generates electromagnetic microwaves that can destroy the tumor.
*** The advantages of microwave ablation (removal of tissue) compared to radiofrequency ablation
Radiofrequency ablation (RFA), also called fulguration, is a medical procedure in which part of the electrical conduction system of the heart, tumor or other dysfunctional tissue is ablated using the heat generated from medium frequency alternati ...
include a generation of higher temperatures and the ability to use multiple needles to better destroy larger tumors.
*** After the treatment, patients follow up with their physician for several months. The treatment team also orders additional imaging scans to evaluate whether the microwave ablation successfully destroyed the tumor.
** Plasma-mediated radiofrequency ablation ("coblation")
*** Radiofrequency ablation
Radiofrequency ablation (RFA), also called fulguration, is a medical procedure in which part of the electrical conduction system of the heart, tumor or other dysfunctional tissue is ablated using the heat generated from medium frequency alternati ...
is a treatment that uses heat to destroy multiple small tumors. An interventional radiologist
Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs bo ...
makes a tiny incision and uses either a computed tomography (CT) scan or ultrasound
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
to guide a special needle to the site of the tumors. Next, radiofrequency (RF) electrodes are placed into the tumor. The electrodes generate an electric current
An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...
(RF energy
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the upp ...
), which produces heat that destroys the tumor. This technique can be repeated at multiple sites, as necessary, before the interventional radiologist
Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs bo ...
removes the RF electrode.
*** After the treatment, patients follow up with their physician for several months. The treatment team orders additional imaging scans to evaluate whether the radiofrequency ablation
Radiofrequency ablation (RFA), also called fulguration, is a medical procedure in which part of the electrical conduction system of the heart, tumor or other dysfunctional tissue is ablated using the heat generated from medium frequency alternati ...
successfully destroyed the tumor.
** Cryoablation
*** Cryoablation
Cryoablation is a process that uses extreme cold to destroy tissue. Cryoablation is performed using hollow needles (cryoprobes) through which cooled, thermally conductive, fluids are circulated. Cryoprobes are positioned adjacent to the target in ...
is a treatment option that destroys cancer cells by applying extremely cold temperatures at the location of the tumor. A small cut is made in the skin and a tiny needle called a cryoprobe
Cryosurgery is the use of extreme cold in surgery to destroy abnormal or diseased tissue; thus, it is the surgical application of cryoablation. The term comes from the Greek words cryo (κρύο) ("icy cold") and surgery (''cheirourgiki'' – χ ...
is inserted. Using image-guidance – either by a computed tomography (CT) scan or by ultrasound
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
–the interventional radiologist
Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs bo ...
maneuvers the cryoprobe
Cryosurgery is the use of extreme cold in surgery to destroy abnormal or diseased tissue; thus, it is the surgical application of cryoablation. The term comes from the Greek words cryo (κρύο) ("icy cold") and surgery (''cheirourgiki'' – χ ...
toward the location of the tumor.
*** Next, the cryoprobes are inserted into the tumor to begin freezing it with a gas called argon
Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abu ...
, creating an "ice ball" over the entire tumor to freeze it for about ten minutes. Nitrogen gas
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh ...
is then used to thaw the tumor for five minutes. This cycle is repeated two or three times depending on the tumor type and size.
Vertebral augmentation
Vertebral augmentation, which includes vertebroplasty and kyphoplasty, are similar spinal procedures in which bone cement
Bone cements have been used very successfully to anchor artificial joints (hip joints, knee joints, shoulder and elbow joints) for more than half a century. Artificial joints (referred to as prostheses) are anchored with bone cement. The bone ce ...
is injected through a small hole in the skin into a fractured vertebra
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...
to try to relieve back pain
Back pain is pain felt in the back. It may be classified as neck pain (cervical), middle back pain (thoracic), lower back pain (lumbar) or coccydynia (tailbone or sacral pain) based on the segment affected. The lumbar area is the most common ...
caused by a vertebral compression fracture
A compression fracture is a collapse of a vertebra. It may be due to trauma or due to a weakening of the vertebra (compare with burst fracture). This weakening is seen in patients with osteoporosis or osteogenesis imperfecta, lytic lesions from ...
s. It was found ineffective in treating osteoporosis
Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to bone fragility, and consequent increase in fracture risk. It is the most common reason for a broken bone ...
-related compression fractures of the spine. The people in both the experimental and placebo groups reported improvement in their pain, suggesting that the benefit is related to the placebo effect
A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like Saline (medicine), saline), sham surgery, and other procedures.
In general ...
. , routine use is thus not recommended.
Sacroplasty
* Sacral insufficiency fractures are an infrequent but often disabling cause of severe low back pain. At times, the pain can be so severe that it may cause the patients to become bedridden, placing them at risk for complications of immobility such as deep vein thrombosis
Deep vein thrombosis (DVT) is a type of venous thrombosis involving the formation of a blood clot in a deep vein, most commonly in the legs or pelvis. A minority of DVTs occur in the arms. Symptoms can include pain, swelling, redness, and enla ...
, pulmonary emboli, muscle atrophy, decubitus ulcers
Pressure ulcers, also known as pressure sores, bed sores or pressure injuries, are localised damage to the skin and/or underlying tissue that usually occur over a bony prominence as a result of usually long-term pressure, or pressure in combi ...
, and bone demineralization
Biomineralization, also written biomineralisation, is the process by which living organisms produce minerals, often to harden or stiffen existing tissues. Such tissues are called mineralized tissues. It is an extremely widespread phenomenon; ...
. Until the development of the sacroplasty
A sacral fracture is a break in the sacrum bone. The sacrum is the large triangular bone that forms the last part of the vertebral column from the fusion of the five sacral vertebrae. Sacral fractures are relatively uncommon. They tend to be ca ...
technique, there was no definitive treatment other than bed rest.
* Sacral insufficiency fractures result from an axial loading mechanism on abnormal bone, such as osteoporosis
Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to bone fragility, and consequent increase in fracture risk. It is the most common reason for a broken bone ...
or underlying neoplasm.
* Analogous to vertebroplasty
Vertebral augmentation, including vertebroplasty and kyphoplasty, refers to similar percutaneous spinal procedures in which bone cement is injected through a small hole in the skin into a fractured vertebra in order to relieve back pain cause ...
, the purpose of sacroplasty is to provide stabilization to prevent painful micromotion at the fracture site. A needle is placed through the skin and into the bone under CT guidance and a polymethylmethacrylate mixture is injected into the sacrum
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30.
The sacrum situates at the upper, back part ...
under real-time fluoroscopy.
* Sacroplasty is a safe and effective procedure in the treatment of sacral insufficiency fractures that can provide substantial pain relief and lead to a better quality of life.
Interventional oncology
Procedures performed
* Image guided ablation: Uses different types of energy to burn (radiofrequency ablation
Radiofrequency ablation (RFA), also called fulguration, is a medical procedure in which part of the electrical conduction system of the heart, tumor or other dysfunctional tissue is ablated using the heat generated from medium frequency alternati ...
(RFA) and microwave ablation (MWA)), deliver electrical fields/electroporate (irreversible electroporation
Irreversible electroporation is a soft tissue Ablation#Medicine, ablation technique using short but strong Electric field, electrical fields to create permanent and hence lethal nanopores in the cell membrane, to disrupt cellular homeostasis. The ...
(IRE)) or freeze (cryoablation
Cryoablation is a process that uses extreme cold to destroy tissue. Cryoablation is performed using hollow needles (cryoprobes) through which cooled, thermally conductive, fluids are circulated. Cryoprobes are positioned adjacent to the target in ...
) solid tumors resulting in tumor cell death. Ablation techniques can be performed throughout the body such as in the lung, liver, kidney, prostate, breast, bone, and other organs using image guidance to place a needle/probe through the skin into the target tissue.
** Radiofrequency ablation video demonstration
Radio Frequency Ablation of Liver Tumor
** Microwave ablation video demonstration
Microwave Ablation Used To Treat Cancer Quickly at Stanford
** Irreversible electroporation video demonstration
Stony Brook Surgery Uses NanoKnife Technology
** Cryoablation video demonstration
Cryoablation Demonstration
* High Intensity Focused Ultrasound: Uses a machine that emits high frequency sound waves to kill cancer cells and provide relief for tumor-related pain, such as in the bone.
* Transarterial embolization (TAE)/Bland embolization
Transarterial bland embolization (TAE, also known as HAE) is a catheter-based tumor treatment of the liver. In this procedure, a variety of embolizing agents (e.g., polyvinyl alcohol, gelfoam, acrylic copolymer gelatin particles, embospheres) can ...
: Injection of embolic material (microparticles, alcohol, glue) through a catheter
In medicine, a catheter (/ˈkæθətər/) is a thin tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgical procedure. Cath ...
into the arteries feeding a tumor to completely occlude the tumor's blood supply and cause cell death. The most common indication is for treatment of unresectable liver cancer ( hepatocellular carcinoma).
* Transarterial chemoembolization
Transcatheter arterial chemoembolization (TACE) is a minimally invasive procedure performed in interventional radiology to restrict a tumor's blood supply. Small embolic particles coated with chemotherapeutic drugs are injected selectively throug ...
(TACE): Injection of a chemotherapy agent often with microparticles through a catheter
In medicine, a catheter (/ˈkæθətər/) is a thin tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgical procedure. Cath ...
into arteries feeding a tumor that both delivers chemotherapy and blocks the blood supply to the tumor to cause cell death
* Can be performed in different ways:
** Conventional transarterial chemoembolization (cTACE): Injection of lipiodol
Lipiodol, also known as ethiodized oil, is a poppyseed oil used by Injection (medicine), injection as a radio-opaque contrast agent that is used to outline structures in radiological investigations. It is used in Transcatheter arterial chemoemboli ...
with high dose chemotherapy with or without microparticles directly into the tumor-feeding arteries.
** Drug eluting bead transarterial chemoembolization (DEB-TACE): delivery of microparticles that are themselves loaded with the chemotherapy agent – typically doxorubicin or irinotecan.
* Selective internal radiation therapy
Selective internal radiation therapy (SIRT), also known as transarterial radioembolization (TARE), radioembolization or intra-arterial microbrachytherapy is a form of radiation therapy used in interventional radiology to treat cancer. It is general ...
(also known as SIRT or Y-90 radioembolization): Injection of small beads loaded with a radioactive isotope, Yittrium-90 (Y-90), into blood vessels feeding a tumor to deliver a lethal dose of radiation to cause cell death. Can be performed in a segmental (radiation segmentectomy) or a lobar ( Radiation Lobectomy) fashion. Radiation lobectomy is commonly performed with the goal of inducing growth of the non-diseased lobe in order to have adequate liver function necessary to undergo surgical resection.
** Y-90 video demonstration
SIR-Spheres Y-90 resin microspheres Mode of Action Video
* Portal vein embolization
Portal vein embolization (PVE) is a preoperative procedure performed in interventional radiology to initiate hypertrophy of the anticipated future liver remnant a couple weeks prior to a major liver resection procedure. The procedure involves in ...
(PVE): delivery of embolic material into the portal vein feeding the lobe of liver containing the tumor(s) of interest to induce growth of the non-diseased lobe to maintain adequate liver function necessary to undergo surgical resection of lobe containing the tumor(s).
Diseases treated
Interventional oncology (IO) procedures are commonly applied to treat primary or 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, ...
cancer. IO treatments may be also offered in combination with surgery, systemic chemotherapy/immunotherapy, and radiation therapy to augment the therapeutic outcome. A variety of interventional oncological treatments for tumors arise:
* Liver cancer: primary liver tumors such as hepatocellular carcinoma or cholangiocarcinoma and liver metastases are often treated by procedures such as transarterial chemoembolization
Transcatheter arterial chemoembolization (TACE) is a minimally invasive procedure performed in interventional radiology to restrict a tumor's blood supply. Small embolic particles coated with chemotherapeutic drugs are injected selectively throug ...
(TACE), Selective internal radiation therapy
Selective internal radiation therapy (SIRT), also known as transarterial radioembolization (TARE), radioembolization or intra-arterial microbrachytherapy is a form of radiation therapy used in interventional radiology to treat cancer. It is general ...
(SIRT/Y-90 radioembolization), portal vein embolization, transarterial/bland embolization, or image guided ablation (RFA, MWA, IRE, Cryoablation)
* 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 tran ...
: lung metastases or inoperable primary lung cancer can be treated by interventional radiology procedures such as image guided ablation (cryoablation, microwave ablation and radiofrequency ablation).
** Cryoablation of lung cancer video demonstration
Cryoablation of a non-small cell lung cancer pleural invasion (www.mposium.com))
* Kidney cancer
Kidney cancer, also known as renal cancer, is a group of cancers that starts in the kidney. Symptoms may include blood in the urine, lump in the abdomen, or back pain. Fever, weight loss, and tiredness may also occur. Complications can include sp ...
: kidney tumors such as renal cell carcinoma
Renal cell carcinoma (RCC) is a kidney cancer that originates in the lining of the Proximal tubule, proximal convoluted tubule, a part of the very small tubes in the kidney that transport primary urine. RCC is the most common type of kidney cance ...
can be treated with image guided ablation (RFA, MWA, cryotherapy) with similar results to partial nephrectomy. Generally, surgery via an either partial or total nephrectomy (removal of kidney) is most often curative but for patients with a smaller lesion or who are not ideal surgical candidates, radiofrequency or cryoablation ablation can be a curative option. Advantages of cryoablation include the ability to visualize the ice ball as well as use more than one probe simultaneously to create the desired ice ball shape. Benign kidney tumors such as angiomyolipomas can be treated with transarterial embolization to shrink the tumor size and reduce the risk of rupture/bleeding. Other embolization
Embolization refers to the passage and lodging of an embolus within the bloodstream. It may be of natural origin ( pathological), in which sense it is also called embolism, for example a pulmonary embolism; or it may be artificially indu ...
s are also performed for symptom relief or prior to surgery to reduce bleeding
* Bone Cancer
A bone tumor is an abnormal growth of tissue in bone, traditionally classified as noncancerous (benign) or cancerous (malignant). Cancerous bone tumors usually originate from a cancer in another part of the body such as from lung, breast, thyro ...
: bone metastases located in the spine, pelvis and long bones can be treated with image guided ablative techniques (RFA, MWA, cryoablation, electrocorporation) with or without injection of cement (cementoplasty) to stabilize the bone. These treatments may be palliatively for bone metastases pain or for some cases such as osteoid osteoma can curatively treat tumors. Embolization
Embolization refers to the passage and lodging of an embolus within the bloodstream. It may be of natural origin ( pathological), in which sense it is also called embolism, for example a pulmonary embolism; or it may be artificially indu ...
s are also performed for prior to surgery to reduce bleeding.
* Breast Cancer
Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or a re ...
: for small, solitary breast cancer image guided ablative techniques are used to treat tumors, however their efficacy versus surgical resection has not yet been studied.
* Prostate Cancer: inoperable tumors can be treated with image guided ablative techniques and more recently irreversible electroporation.
** Irreversible electroporation video demonstration
Irreversible Electroporation (NanoKnife®) to Treat Prostate Tumors , Memorial Sloan Kettering Cancer Center
* Pancreatic cancer
Pancreatic cancer arises when cell (biology), cells in the pancreas, a glandular organ behind the stomach, begin to multiply out of control and form a Neoplasm, mass. These cancerous cells have the malignant, ability to invade other parts of t ...
: inoperable, or borderline resectable, locally advanced pancreatic adenocarcinoma can be treated with irreversible electroporation
Vascular disease
Vascular Disease refers to disorders of the vasculature or circulatory system
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
, most commonly involving the arteries
An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...
, veins
Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...
and lymphatics. The symptoms related to vascular disease can range from asymptomatic, bothersome symptoms or limb and/or life-threatening conditions.
Vascular and Interventional Radiologists are at the forefront of treating a wide variety of vascular diseases.
Basics of vascular intervention
Since its development by Charles Dotter
Charles Theodore Dotter (14 June 1920 – 15 February 1985) was a pioneering US vascular radiologist who is credited with developing interventional radiology. Dotter, with his trainee Dr Melvin P. Judkins, described angioplasty in 1964.
Dott ...
when he did a percutaneous peripheral vascular revascularization procedure for the first time on January 16, 1964, on Laura Shaw, Vascular & Interventional Radiology (commonly Interventional Radiology or IR) distinguished itself from earlier approaches to vascular disease by the use of medical imaging to guide endovascular therapies (fixing this from inside the vessel). The Seldinger technique
The Seldinger technique, also known as Seldinger wire technique, is a medical procedure to obtain safe access to blood vessels and other hollow organs. It is named after Sven Ivar Seldinger (1921–1998), a Swedish radiologist who introduced th ...
is the basic principle that underlies endovascular procedures. Briefly, this involves using a needle to puncture a target vessel, then using a series of small medical guidewires and catheters to pass various tools inside for treatment. When these minimally-invasive techniques can be used, patients avoid the need for larger surgical exposure to treat diseased vessels. Though numerous factors can affect patient's post-operative course, in general an endovascular approach is associated with a more rapid recovery time compared to a traditional open vascular surgery.
Over the past few decades, many endovascular procedures have been developed and refined. Numerous tools are at the disposal of modern Vascular and Interventional Radiologists to perform these procedures, and developing new tools is a burgeoning focus of international research.
While some interventional radiology endovascular procedures are highly specialized, a few standard techniques apply to most:
# Angiography
Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is perfor ...
: Sometimes referred to as traditional angiography, catheter angiography or digital subtraction angiography (DSA.) A small needle is inserted into a blood vessel, then exchanged for a catheter over a wire. The catheter is directed at the vessel to be studied, and contrast is directly injected to evaluate the lumen under video X-ray. This is an older technique than modern CT angiography
Computed tomography angiography (also called CT angiography or CTA) is a computed tomography technique used for angiography—the visualization of arteries and veins—throughout the human body. Using contrast injected into the blood vessels, i ...
or MR angiography
Magnetic resonance angiography (MRA) is a group of techniques based on magnetic resonance imaging (MRI) to image blood vessels. Magnetic resonance angiography is used to generate images of arteries (and less commonly veins) in order to evaluate t ...
, but provides unique advantages. With a catheter in place, provocative maneuvers can be performed such as breath holds or instillation of vasodilators, to evaluate a patient's blood flow dynamically. This can reproduce symptoms and identify functional abnormalities in a vessel that a static CT or MR imaging cannot. Angiography provides the basis for all endovascular therapy.
# Balloon angiography
Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is perfor ...
: The foundational IR procedure. Small balloons can be inflated inside a narrowed vessel to open it. These can then be safely deflated and removed. Some balloons have a specialized surface material, such as fine razor blades ("cutting balloons") to crack the plaque or instill a coating of medicine ("Drug-coated balloon") that keeps the vessel open longer.
# Stents and stent-grafts: Stent
In medicine, a stent is a metal or plastic tube inserted into the lumen of an anatomic vessel or duct to keep the passageway open, and stenting is the placement of a stent. A wide variety of stents are used for different purposes, from expandab ...
s are used to provide a scaffold along a segment of diseased vessel. These are available in a variety of sizes to accommodate placement in vessels throughout the body from head to toe. Endografts are stents with fabric covering that are used for the treatment of bleeding or aneurysms. These devices typically come folded up very small on a scaffold, or delivery device, such as a balloon. Stents then expand into pipe-like cylinders (demonstratio
video
to support a vessel wall and keep the pathway for blood flow as large as possible. Some stents are bare-metal, allowing blood to leak through the walls of the stent, while others have a thin covering that keeps flow moving through only from one open end to the other. These can be used for a variety of applications depending on the vessel and the nature of the disease. Sometimes multiple stents are deployed end-to-end or side by side to maintain laminar flow. Like balloons, some stents come coated with medicine to help prevent the treated vessel from closing again.
# Embolization
Embolization refers to the passage and lodging of an embolus within the bloodstream. It may be of natural origin ( pathological), in which sense it is also called embolism, for example a pulmonary embolism; or it may be artificially indu ...
: The goal of embolization is to decrease or stop flow only in a target vessel, while avoiding cutting off the flow to nearby non-target vessels. This can be performed to stop active bleeding (as in trauma) to limit anticipated blood loss (such as in a complex surgery,) or to cut off blood supply to either an abnormal vessel (e.g., aneurysm) or abnormal structure (e.g., tumor.) There are many embolic agents available, from metallic plugs and coils to various biologically compatible particles and glues. Depending on the clinical situation, embolization can be temporary or permanent.
# Thrombolysis
Thrombolysis, also called fibrinolytic therapy, is the breakdown (lysis) of blood clots formed in blood vessels, using medication. It is used in ST elevation myocardial infarction, stroke, and in cases of severe venous thromboembolism (massive ...
and thrombectomy
Mechanical thrombectomy, or simply thrombectomy, is the interventional procedure of removing a blood clot (thrombus) from a blood vessel. It is commonly performed in the cerebral arteries (interventional neuroradiology). The effectiveness of throm ...
: The body forms blood clots as a natural protective mechanism against bleeding. However, when arising outside this context, blood clots can wreak havoc in the human body including disabling strokes. Thrombolysis is the process of breaking down blood clots, by injecting them with powerful medications. Thrombectomy involves using a device to remove the clot directly.
The goal of endovascular therapy is to revascularize an affected or diseased vessel.
Arterial disease
Arteries
An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...
are the component of the circulatory system
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
that carry oxygenated blood away from the heart
The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...
to the vital organs
In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a f ...
and extremities. Arteries have relatively thick, muscular walls, composed of multiple layers, because they transport freshly oxygenated blood through the body at relatively high pressures. Arterial diseases can affect one or multiple layers of the artery wall.
The aorta
The aorta ( ) is the main and largest artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries). The aorta distributes ...
is the largest artery in the body, and the major aortic branches continue to divide multiple times, giving way to smaller arteries, muscular arterioles
An arteriole is a small-diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries.
Arterioles have muscular walls (usually only one to two layers of smooth muscle cells) and are the primar ...
and thin-walled capillaries
A capillary is a small blood vessel from 5 to 10 micrometres (μm) in diameter. Capillaries are composed of only the tunica intima, consisting of a thin wall of simple squamous endothelial cells. They are the smallest blood vessels in the body: ...
. In contrast to arteries, capillaries have thin single-layered walls, so oxygen and nutrients can be exchanged with tissues in capillary beds before the de-oxygenated blood is carried away by the venous system.
Perfusion refers to the flow of oxygen and nutrient rich blood into the capillary beds of the muscles and organs, this is critical for their function. The lack of adequate perfusion is referred to as ischemia
Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems wi ...
and is typically the cause of symptoms related to vascular disease. The goal of revascularization therapies, whether endovascular or surgical, is to re-establish or optimize perfusion and stop ischemia.
Atherosclerosis
Atherosclerosis is a pattern of the disease arteriosclerosis in which the wall of the artery develops abnormalities, called lesions. These lesions may lead to narrowing due to the buildup of atheroma, atheromatous plaque. At onset there are usu ...
refers to a progressive narrowing of the arteries due to atheroma
An atheroma, or atheromatous plaque, is an abnormal and reversible accumulation of material in the inner layer of an arterial wall.
The material consists of mostly macrophage cells, or debris, containing lipids, calcium and a variable amount o ...
, derived from the Greek word for gruel or porridge. Atheromatous plaque is a mixture of fat and inflammatory debris that sticks to the inner walls of an artery. Plaque can be soft or become firm as it accrues layers of calcium, a byproduct of chronic inflammation. Atherosclerosis has no single cause but many recognized risk factors. Some risk factors are modifiable, and others are not. Age and genetic predispositions are an example of ''non-modifiable'' risk factors. Medical management of atherosclerosis aims to address the many other known ''modifiable'' risk factors, such as smoking, diet, exercise as well as blood sugar levels in patients with diabetes. Using medications to control blood pressure and cholesterol have also been shown beneficial.
Atherosclerosis is described, evaluated, and treated differently depending on the affected artery, as described below. However, multiple studies have shown strong correlations between the different types of atherosclerosis. In particular, patients with Peripheral Arterial Disease have an increased risk of Coronary Artery Disease, and severe Peripheral Artery Disease symptoms can be a predictor of cardiac related mortality. The majority of patients begin to develop symptoms from ischemia around middle age, even though vessel narrowing can develop silently and slowly over decades. Unfortunately, sudden cardiac death or stroke can be a patient's first sign of vascular disease. Therefore, controlling risk factors is crucial in those with known atherosclerosis to prevent progression of disease, and screening is recommended by some Vascular Disease Specialists for those at increased risk, such as those with diabetes, smoking or a strong family history of cardiovascular disease.
Screening tests typically use the non invasive evaluation called the Ankle-Brachial Index, which compares the blood pressure between the arm and the ankle. This can help detect narrowing in the major vessels of the chest, abdomen, pelvis, and legs. CT scans of the heart with evaluations of coronary artery calcium are also used in some instances to stratify risk of coronary artery disease.
Historically, open vascular surgical approaches were required for all critically advanced atherosclerotic disease. An endarterectomy
Endarterectomy is a surgical procedure to remove the atheromatous ''plaque'' material, or blockage, in the lining of an artery constricted by the buildup of deposits. It is carried out by separating the plaque from the arterial wall.
It was firs ...
is a large operation, where blood flow is temporarily stopped using clamps, the vessel is cut open, the plaque removed and then the vessel resealed. If an occlusion is too dense or complex, a bypass could also be performed, where two segments of vessel are bridged by an additional vein or synthetic graft.
Modern endovascular approaches to treating atherosclerosis can include combinations of angioplasty, stenting, and atherectomy (removal of plaque).
# Peripheral artery disease
Peripheral artery disease (PAD) is an abnormal narrowing of arteries other than those that supply the heart or brain. When narrowing occurs in the heart, it is called coronary artery disease, and in the brain, it is called cerebrovascular dis ...
(PAD; sometimes peripheral vascular disease, PVD) is most often a result of atherosclerosis and affects the arteries of the lower extremities, those below the aortic bifurcation. A hallmark symptom is claudication
Claudication is a medical term usually referring to impairment in walking, or pain, discomfort, numbness, or tiredness in the legs that occurs during walking or standing and is relieved by rest. The perceived level of pain from claudication can be ...
, or progressive pain in a limb associated with activity, due to ischemia
Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems wi ...
. As the perfusion to a limb diminishes further pain in the foot can occur even at rest and in fact the tissues of the foot can even die.
There are several systems for staging PAD, but an often used scale is the revised Rutherford classification. Plaque and blood flow can be evaluated using ultrasound
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
, CT angiography
Computed tomography angiography (also called CT angiography or CTA) is a computed tomography technique used for angiography—the visualization of arteries and veins—throughout the human body. Using contrast injected into the blood vessels, i ...
, MR angiography, and catheter-based angiography to establish anatomic segments of disease. The severity of ischemia can be evaluated by correlating symptoms and non-invasive physiologic vascular studies including toe pressures, TCPO2, and skin perfusion studies.
Certain monitored exercises, such as walking regimens, have been shown to significantly improve walking distance especially when used consistently for at least 6 months. When medical management fails, vascular interventional radiologists can attempt to restore blood flow to extremities using angioplasty and stenting. Sometimes repeat interventions are required. The goal of therapy is to maintain perfusion, avoid amputation and preserve the limb structure and function.
# Critical limb ischemia
Chronic limb threatening ischemia (CLTI), also known as critical limb ischemia (CLI), is an advanced stage of peripheral artery disease (PAD). It is defined as ischemic rest pain, arterial insufficiency ulcers, and gangrene. The latter two cond ...
(CLI) is a severe variant of PAD (Rutherford 4 and above) characterized by rest pain or tissue loss. Each year this affects just under 1% of the population, but develops in approximately 11% of PAD patients. Symptoms develop due to chronic ischemia from vessel plaque burden, which builds up over time. Rest pain is a continuous burning pain in the limb that is aggravated by elevating it and improved by dangling over the bed as the perfusion is so poor that it becomes gravity dependent. Tissue loss refers to arterial insufficiency ulcers
An ulcer is a discontinuity or break in a bodily membrane that impedes normal function of the affected organ. According to Robbins's pathology, "ulcer is the breach of the continuity of skin, epithelium or mucous membrane caused by sloughing o ...
, which can progress to frank gangrene
Gangrene is a type of tissue death caused by a lack of blood supply. Symptoms may include a change in skin color to red or black, numbness, swelling, pain, skin breakdown, and coolness. The feet and hands are most commonly affected. If the ga ...
. Arterial ulcers are classically painful and located on the distal aspect of the extremities. A diagnosis of CLI incurs a higher risk of amputation (up to 25% within 1 year) and death (up to 25% within 1 year.) This is a serious condition that requires multi-modality treatment. The goal of Vascular Interventional Radiology and others who work in Limb Salvage is to minimize tissue loss by preserving direct blood flow to the affected limb by treating vessel blockages, controlling any infection and optimizing wound care. Increasingly, this can be accomplished with primary endovascular therapies before open surgery is considered.
# Acute limb ischaemia
Acute limb ischaemia (ALI) occurs when there is a sudden lack of blood flow to a limb.
Acute limb ischaemia is caused by embolism or thrombosis, or rarely by dissection or trauma. Thrombosis is usually caused by peripheral vascular disease (ath ...
(ALI) occurs when blood flow to an extremity is abruptly cut off. It occurs most commonly in those with a history of atrial fibrillation or underlying PAD/PVD. Unlike chronic ischemia, which the body can partially adapt to, ALI is an emergency that can result in an amputation or even death if not treated in hours. It is typically due to an embolus from the heart or a thrombus that develops in a pre-existing area of narrowed artery. Once diagnosed clinically, CT or MR angiography may be used to evaluate the cause and extent of disease. Vascular interventional radiologists may use thrombectomy devices or clot dissolving medications to remove or dissolve the clot. Surgical options include open thrombectomy and even vascular bypass.
# Carotid atherosclerosis involves the major branch arteries that provide blood to the brain. Carotid artery disease incurs an increased risk of stroke by two different mechanisms, either from limiting overall blood flow or more often by showering pieces of plaque or clot deep into the small vessels in the brain. Either can result in degrees of cerebral ischemia
Brain ischemia is a condition in which there is insufficient bloodflow to the brain to meet metabolic demand. This leads to poor oxygen supply or cerebral hypoxia and thus leads to the death of brain tissue or cerebral infarction/ischemic stroke. ...
. Carotid artery disease can be typically addressed with open surgical techniques (carotid endarterectomy
Carotid endarterectomy is a surgery, surgical procedure used to reduce the risk of stroke from carotid artery stenosis (narrowing the internal carotid artery). In endarterectomy, the surgeon opens the artery and removes the plaque. The plaque for ...
) or though endovascular stenting.
# Chronic mesenteric ischemia
Intestinal ischemia is a medical condition in which injury to the large or small intestine occurs due to not enough blood supply. It can come on suddenly, known as acute intestinal ischemia, or gradually, known as chronic intestinal ischemia. The ...
can produce severe pain with eating and result in food fear and weight loss. These vascular disorders can be repaired by endovascular approaches using angioplasty and stenting.
# Renal arterial ischemia can contribute to hypertension, which can be severe and refractory to medical therapy.
# Coronary artery disease
Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), myocardial ischemia, or simply heart disease, involves the reduction of blood flow to the heart muscle due to build-up of atherosclerotic pla ...
involves the arteries supplying blood to heart muscle. Coronary ischemia results in myocardial infarction, also known as a heart attack. The coronary arteries were one of the earliest widely accepted applications of angioplasty and stenting developed by cardiology and interventional radiology.
# Aortoiliac occlusive disease
In medicine, aortoiliac occlusive disease is a form of central artery disease involving the blockage of the abdominal aorta as it transitions into the common iliac arteries.
Signs and symptoms
Classically, it is described in male patients as a t ...
(Leriche syndrome) is a constellation of symptoms due to significant occlusion of the distal aorta and common iliac arteries, most commonly by atherosclerotic disease The classic symptoms include buttock claudication and erectile dysfunction, with decreased femoral pulses. Additional symptoms of critical limb ischemia can be present. Both surgical and endovascular approaches to revascularization
In medical and surgical therapy, revascularization is the restoration of perfusion to a body part or organ that has had ischemia. It is typically accomplished by surgical means. Vascular bypass and angioplasty are the two primary means of rev ...
can be considered.
Aneurysm
An aneurysm is an outward bulging, likened to a bubble or balloon, caused by a localized, abnormal, weak spot on a blood vessel wall. Aneurysms may be a result of a hereditary condition or an acquired disease. Aneurysms can also be a nidus (s ...
refers to pathologic dilation of an artery to greater than 1.5 times its normal size. True vascular aneurysms are due to degenerative processes in the wall of the artery. Aneurysms can be solitary or multiple and are sometimes found in association with various clinical syndromes, including forms of vasculitis or connective tissue diseases. Aneurysms are typically classified by major shapes, either fusiform (tubular) or saccular (eccentric). Ectasia is another broad term for an enlarged vessel, but is not necessarily pathological. Rupture is a dreaded complication of aneurysms that can lead to extensive, difficult to control bleeding. Aneurysms can also clot, or thrombose, and rapidly occlude the involved vessel, leading to acute distal ischemia.
# Aortic aneurysms include thoracic
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the crea ...
, abdominal
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso ...
or thoracoabdominal. Treatment strategies are customized depending on the location, size, rate of growth and extent of the aneurysm as well as the medical comorbidities of the patient. For example, an intact, small but slowly growing aneurysm may be safely monitored with serial imaging for months or years before elective repair is considered. Elective endovascular aortic grafting is now routinely attempted when possible. Endovascular aortic repair (EVAR) refers to treatment of an abdominal aortic aneurysm, while thoracic endovascular aortic repair (TEVAR) is performed on the thoracic aorta. A ruptured aneurysm may be taken emergently for open, endovascular or combination repair.
A variety of endovascular grafts are available, and each has advantages and disadvantages depending on the characteristics of the aneurysm and patient.
# Aneurysms refers to aneurysms in the arms and legs. These can typically be evaluated and monitored with vascular ultrasound, CT angiography and MR angiography. Popliteal aneurysms are associated with distal embolization and are also associated with concurrent contralateral popliteal artery aneurysms and abdominal aortic aneurysms. When amenable, endovascular treatments for popliteal aneurysms can include endovascular stenting or surgical bypass.
# Visceral aneurysm affect the vessels that supply the solid organs. Similar to other aneurysms, treatment depends on several factors including size, location, shape and growth. Endovascular treatments for visceral aneurysms can usually be performed with less morbidity when compared to open surgical techniques.
# Intracranial aneurysms arise in the arterial supply of the brain. Endovascular approaches to treatment include stenting and coiling and are preferable in most cases since clipping and resection require a surgical craniotomy. Rupture of intracranial aneurysms can have devastating clinical effects. For further discussion, refer to the neuro-interventional radiology section.
# Pseudoaneurysm
A pseudoaneurysm, also known as a false aneurysm, is a locally contained hematoma outside an artery or heart due to damage to the vessel wall. The injury goes through all the three layers of the arterial wall causing a leak, which is contained b ...
is when there is not all 3 layers surrounding the artery. These structures can technically be considered a type of contained bleed. They are most often due to focal damage to a blood vessel, which could be the result of trauma, infection or inflammation. Splenic artery pseudoaneurysms, for example, may develop as a result of pancreatitis. In some cases, pseudoaneurysms of the femoral and radial arterials can be a complication of arterial access for endovascular procedures. Depending on the size and location of the pseudoaneurysm, it may be treatable with minimally-invasive Interventional Radiology methods, though some particularly the infected ones may require open surgery.
Dissection refers to a tear in the inner layer of the arterial wall. Blood pumps into this defect and dissects its way between the layers in the wall of an artery, creating a false channel separate from the true arterial lumen. Dissections can develop due to trauma, spontaneously due to high blood pressure and native vascular disease, or in some cases as a complication of prior surgical or endovascular treatment.
When an arterial dissection expands, it can restrict normal flow through the affected artery or potentially block the origin of a branch vessel- this can compromise distal perfusion in either case. When acute and symptomatic, this is an emergency that requires prompt treatment.
However, as medical imaging has improved, chronic, asymptomatic dissections have also been discovered, and in some cases these may be safely managed with blood pressure control, follow-up imaging and proper counseling for the warning signs of potential ischemia.
Dissections can occur in any artery and are named for their vessel of origin. Aortic dissections can be further classified and treated depending on whether they involve the thoracic aorta, the abdominal aorta or both. Classic pain related to acute aortic dissections is described as "tearing" or "ripping" and possibly radiating to a patient's back. Acute aortic dissection can be difficult to diagnose but is more common than aortic aneurysm rupture.
Thoracic aortic dissections are further characterized with the Stanford classification. Type A dissections involve the root and ascending aorta. These require prompt treatment, which currently is mostly surgical in nature. Type B dissections begin in the distal aortic arch beyond the left subclavian artery origin, and may often be addressed with pain medication and blood pressure control. If the type B aortic dissection results in poor circulation to the intestines, kidneys or legs it often requires urgent endovascular repair with endografts and/or fenestrations. If a type B aortic dissection has ruptured, or has features that indicate impending rupture, they are urgently repaired too.
Dissections can also arise in virtually any other artery. Carotid artery dissection, for example, places patients at increased risk for stroke and may extend further into the blood vessels within the brain. Vertebral artery dissection
Vertebral artery dissection (VAD) is a flap-like tear of the inner lining of the vertebral artery, which is located in the neck and supplies blood to the brain. After the tear, blood enters the arterial wall and forms a blood clot, thickening t ...
are less common but also dangerous for similar reasons. Mesenteric artery dissection may limit the blood supply to the intestines. Renal artery dissections can decrease blood flow to the kidneys and contribute to hypertension. Peripheral arterial dissections can be found elsewhere in the arms and legs. These dissections can occur primarily due to focal traumas, underlying vascular disease, or as an extension of a larger, complex aortic dissection that tears further into these smaller branches.
Treatment of dissections depends on several factors, including the location, extent, how long it has been developing (acute or chronic) and whether it is limiting perfusion. Surgical approaches to dissections can include reconstructing the aorta, surgical bypass and surgical fenestration. Like other arterial disorders, endovascular approaches to dissection such as stent-grafting and percutaneous fenestration can be utilized, either primarily or in combination with surgery depending on the complexity of the dissection.
Penetrating aortic ulcer (PAU) is an advanced focal form atherosclerosis, most often encountered in the aorta. It starts as a small plaque in the inner-most layer of the aorta called the intima, but the inflammatory process ulcerates and penetrates through this layer into the media. While PAU is considered a distinct entity, many think this is a precursor lesion to dissection or aneurysm. Along with intramural hematoma, aneurysm and dissection, PAU is recognized as one of several acute aortic syndrome
Acute aortic syndrome (AAS) describes a range of severe, painful, potentially life-threatening abnormalities of the aorta. These include aortic dissection, intramural thrombus, and penetrating atherosclerotic aortic ulcer. AAS can be caused by a l ...
s — a spectrum of related conditions correlated to potential aortic rupture. They thus have a high potential morbidity and mortality, and should at least be followed closely.
Acute or active bleeding can occur throughout the human body due to a variety of causes. Interventional radiologists can address bleeding with embolization, usually with small plastic particles, glues or coils. Traumatic rupture of a blood vessel, for example, may be addressed this way if a patient is at risk of fatal bleeding. This has revolutionized medicine and interventional radiologists commonly treat refractory nose bleeds, excessive coughing of blood, intestinal bleeding, post-pregnancy bleeding, spontaneous intra-abdominal on intra-thoracic bleeding, bleeding related to trauma and post-surgical bleeding. In some instances where severe bleeding is anticipated, such as in complex surgery or the excision of a highly vascular tumor, interventional radiologists may embolize certain target blood vessels prior to the operation to prevent major blood loss.
Transplant organs rely on healthy blood supply to survive. In some instances, the arteries that feed a transplant may narrow, typically where the donor vessel is sewn to the recipient. Interventional radiologists evaluate the blood supply of these patient's and may use balloons or stents to open narrowed vessels and keep the transplant organ functional.
Venous disease
The veins
Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...
of the human body are responsible for returning de-oxygenated blood back to the heart. Like a rock rolling down a hill, blood flows from the highest pressure (the blood in the aorta) to the lower venous pressure (the blood in the vena cava as it empties back to the heart.) Unlike arteries, veins are thin walled and distensible, allowing them to accommodate large volumes of blood without significant changes in pressure. In fact, the venous system is so low pressure that veins have valves to keep blood from flowing backward. The motion of the human body helps pump blood through the veins- squeezing leg muscles while walking, for instance, helps push venous blood back up to the heart against the pull of gravity. Unfortunately, without this extra push some blood can sit stagnant in veins, leading to a multitude of clinical problems. The largest vein in the body is the vena cava. The superior vena cava (SVC) drains blood from the top half of the body while the inferior vena cava (IVC) drains blood from below the diaphragm. Elsewhere in the body, veins can be categorized into superficial, primarily associated with the skin and soft tissues, or deep veins, which drain muscles and organs.
Venous access
Chronic kidney disease (CKD or chronic renal disease) is a condition in which there is a progressive loss of kidney function. It has numerous recognized causes and risk factors. CKD affects approximately 14% of the world population, and over 600,000 people in the United States alone. There are five recognized stages of CKD, the fifth stage is also called end-stage renal disease (ESRD) and invariably requires some form of renal replacement therapy
Renal replacement therapy (RRT) is therapy that replaces the normal blood-filtering function of the kidneys. It is used when the kidneys are not working well, which is called kidney failure and includes acute kidney injury and chronic kidney di ...
.
Around the turn of the 20th century, breakthroughs in our understanding of renal physiology led many to believe that dialysis using artificial kidneys was a potential cure for renal disease. Over 100 years later, the only available curative, renal replacement therapy for CKD is kidney transplantation. However, many patients can live for decades utilizing dialysis.
Dialyzer technology initially outpaced the ability of clinicians to apply it to patients. In the 1920s, the first dialysis catheter was created using thin fragile glass tubes. Early methods required surgical incision to reach large vessels, which carried a large risk of major bleeding. The first somewhat permanent, reliable dialysis access, the Scribner Teflon Shunt, was invented nearly 40 years later and allowed a patient with kidney failure
Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as eit ...
to survive 11 more years. As medicine and surgery have grown more sophisticated, more patients now live with chronic renal disease than ever before. The most common type of dialysis in the United States is hemodialysis, which can be performed through several types of vascular access. The arteriovenous fistula (AVF) is the preferred method. Arteriovenous fistula are created surgically by directly connecting an artery and a vein, most commonly in the arm. An arteriovenous graft (AVG) relies on the same principle but bridges the gap between the artery and vein with a medical-grade prosthetic shunt. Over time, altered flow mechanics can result in changes within the involved vessels. Vascular narrowing, thrombosis, aneurysms and pseudoaneurysms are commonly encountered complications over the life of an AVF or AVG. Interventional radiologists can use angiography to evaluate these structures (commonly called a Fistulogram) and treat dysfunctional access with angioplasty, stenting, and thrombectomy. Most patients require regular evaluation and treatment to keep their access working. When possible, AVFs are preferred to AVGs due to their relatively lower complication rate and longer patency. Th
Fistula First
initiative works to promote physician and patient awareness about the benefits of first attempting hemodialysis through a fistula. There are a few devices (endo AVF) that are being utilized by interventional radiologists to percutaneously create fistulas in a minimally invasive fashion.
Dialysis catheters include temporary and tunneled large-bore central venous access lines placed for administering hemodialysis. When possible, these catheters are placed in the right internal jugular vein, but the left internal jugular and femoral veins may also be utilized. Temporary dialysis lines may be placed when patients are hospitalized and either too sick or at a high risk of bleeding. Permanent hemodialysis catheters are longer overall but a segment is tunneled through the skin of the chest, which lets the catheter lie flat and lowers the risk of infection.
Central venous access refers to a variety of intravenous catheters placed in patients requiring certain long-term medications. These are much smaller in diameter than dialysis lines, but are larger and longer than a standard intravenous line (IV.) Examples include Hickman catheters, peripherally inserted central cathethers (or PICCs), tunneled small bore central venous catheters, and mediports. These lines differ in where they are inserted but are all placed under imaging guidance and adjusted so the end of the catheter sits in the vena cava adjacent to the heart. These catheters are designed to deliver strong medications, such as chemotherapy or prolonged courses of antibiotics, which are either dosed too frequently to keep placing new IVs or are too irritating to small veins be injected through a standard IV.
References
Further reading
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