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Acoustocerebrography
Acoustocerebrography (ACG) is a medical test used to diagnose changes and problems in the brain and the central nervous system. It allows for the noninvasive examination of the brain's cellular and molecular structure. It can also be applied as a means to diagnose and monitor intracranial pressure, for example as incorporated into continuous brain monitoring devices. ACG uses molecular acoustics, in audible and ultrasound frequency ranges, to monitor changes. It may use microphones, accelerometers, and multifrequency ultrasonic transducers. It does not use any radiation and is completely free of any side effects. ACG also facilitates blood flow analysis as well as the detection of obstructions in cerebral blood flow (from cerebral embolism) or bleeding (from cerebral hemorrhage). Passive and active acoustocerebrography Passive acoustocerebrography All brain tissue is influenced by blood circulating in the brain's vascular system. With each heartbeat, blood circulates in the skull, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultrasonic Transducer
Ultrasonic transducers and ultrasonic sensors are devices that generate or sense ultrasound energy. They can be divided into three broad categories: transmitters, receivers and transceivers. Transmitters convert electrical signals into ultrasound, receivers convert ultrasound into electrical signals, and transceivers can both transmit and receive ultrasound. Applications and performance Ultrasound can be used for measuring wind speed and direction (anemometer), tank or channel fluid level, and speed through air or water. For measuring speed or direction, a device uses multiple detectors and calculates the speed from the relative distances to particulates in the air or water. To measure tank or channel liquid level, and also sea level (tide gauge), the sensor measures the distance (ranging) to the surface of the fluid. Further applications include: humidifiers, sonar, medical ultrasonography, burglar alarms, non-destructive testing and wireless charging. Systems typically use a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subarachnoid Hemorrhage
Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain. Symptoms may include a severe headache of rapid onset, vomiting, decreased level of consciousness, fever, and sometimes seizures. Neck stiffness or neck pain are also relatively common. In about a quarter of people a small bleed with resolving symptoms occurs within a month of a larger bleed. SAH may occur as a result of a head injury or spontaneously, usually from a ruptured cerebral aneurysm. Risk factors for spontaneous cases include high blood pressure, smoking, family history, alcoholism, and cocaine use. Generally, the diagnosis can be determined by a CT scan of the head if done within six hours of symptom onset. Occasionally, a lumbar puncture is also required. After confirmation further tests are usually performed to determine the underlying cause. Treatment is by prompt neurosurgery or endovascular coiling. Medicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stenosis
A stenosis (from Ancient Greek στενός, "narrow") is an abnormal narrowing in a blood vessel or other tubular organ or structure such as foramina and canals. It is also sometimes called a stricture (as in urethral stricture). ''Stricture'' as a term is usually used when narrowing is caused by contraction of smooth muscle (e.g. achalasia, prinzmetal angina); ''stenosis'' is usually used when narrowing is caused by lesion that reduces the space of lumen (e.g. atherosclerosis). The term coarctation is another synonym, but is commonly used only in the context of aortic coarctation. Restenosis is the recurrence of stenosis after a procedure. Types The resulting syndrome depends on the structure affected. Examples of vascular stenotic lesions include: * Intermittent claudication (peripheral artery stenosis) * Angina ( coronary artery stenosis) * Carotid artery stenosis which predispose to (strokes and transient ischaemic episodes) * Renal artery stenosis The types of sten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embolisms
An embolism is the lodging of an embolus, a blockage-causing piece of material, inside a blood vessel. The embolus may be a blood clot (thrombus), a fat globule ( fat embolism), a bubble of air or other gas (gas embolism), amniotic fluid (amniotic fluid embolism), or foreign material. An embolism can cause partial or total blockage of blood flow in the affected vessel. Such a blockage (vascular occlusion) may affect a part of the body distant from the origin of the embolus. An embolism in which the embolus is a piece of thrombus is called a thromboembolism. An embolism is usually a pathological event, caused by illness or injury. Sometimes it is created intentionally for a therapeutic reason, such as to stop bleeding or to kill a cancerous tumor by stopping its blood supply. Such therapy is called embolization. Classification There are different types of embolism, some of which are listed below. Embolism can be classified based on where it enters the circulation, either in ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcranial Doppler
Transcranial Doppler (TCD) and transcranial color Doppler (TCCD) are types of Doppler ultrasonography that measure the velocity of blood flow through the brain's blood vessels by measuring the echoes of ultrasound waves moving transcranially (through the cranium). These modes of medical imaging conduct a spectral analysis of the acoustic signals they receive and can therefore be classified as methods of active acoustocerebrography. They are used as tests to help diagnose emboli, stenosis, vasospasm from a subarachnoid hemorrhage (bleeding from a ruptured aneurysm), and other problems. These relatively quick and inexpensive tests are growing in popularity. The tests are effective for detecting sickle cell disease, ischemic cerebrovascular disease, subarachnoid hemorrhage, arteriovenous malformations, and cerebral circulatory arrest. The tests are possibly useful for perioperative monitoring and meningeal infection. The equipment used for these tests is becoming increasingly portab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectrum
A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors in visible light after passing through a prism. As scientific understanding of light advanced, it came to apply to the entire electromagnetic spectrum. It thereby became a mapping of a range of magnitudes (wavelengths) to a range of qualities, which are the perceived "colors of the rainbow" and other properties which correspond to wavelengths that lie outside of the visible light spectrum. Spectrum has since been applied by analogy to topics outside optics. Thus, one might talk about the " spectrum of political opinion", or the "spectrum of activity" of a drug, or the "autism spectrum". In these uses, values within a spectrum may not be associated with precisely quantifiable numbers or definitions. Such uses imply a broad range of condition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 brain, and absorbed in the arachnoid granulations. There is about 125 mL of CSF at any one time, and about 500 mL is generated every day. CSF acts as a shock absorber, cushion or buffer, providing basic mechanical and immunological protection to the brain inside the skull. CSF also serves a vital function in the cerebral autoregulation of cerebral blood flow. CSF occupies the subarachnoid space (between the arachnoid mater and the pia mater) and the ventricular system around and inside the brain and spinal cord. It fills the ventricles of the brain, cisterns, and sulci, as well as the central canal of the spinal cord. There is also a connection from the subarachnoid space to the bony labyrinth of the inner ear via the perilymphat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerebral Hemorrhage
Intracerebral hemorrhage (ICH), also known as cerebral bleed, intraparenchymal bleed, and hemorrhagic stroke, or haemorrhagic stroke, is a sudden bleeding into the tissues of the brain, into its ventricles, or into both. It is one kind of bleeding within the skull and one kind of stroke. Symptoms can include headache, one-sided weakness, vomiting, seizures, decreased level of consciousness, and neck stiffness. Often, symptoms get worse over time. Fever is also common. Causes include brain trauma, aneurysms, arteriovenous malformations, and brain tumors. The biggest risk factors for spontaneous bleeding are high blood pressure and amyloidosis. Other risk factors include alcoholism, low cholesterol, blood thinners, and cocaine use. Diagnosis is typically by CT scan. Other conditions that may present similarly include ischemic stroke. Treatment should typically be carried out in an intensive care unit. Guidelines recommend decreasing the blood pressure to a systolic of 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embolism
An embolism is the lodging of an embolus, a blockage-causing piece of material, inside a blood vessel. The embolus may be a blood clot (thrombus), a fat globule ( fat embolism), a bubble of air or other gas (gas embolism), amniotic fluid (amniotic fluid embolism), or foreign material. An embolism can cause partial or total blockage of blood flow in the affected vessel. Such a blockage (vascular occlusion) may affect a part of the body distant from the origin of the embolus. An embolism in which the embolus is a piece of thrombus is called a thromboembolism. An embolism is usually a pathological event, caused by illness or injury. Sometimes it is created intentionally for a therapeutic reason, such as to stop bleeding or to kill a cancerous tumor by stopping its blood supply. Such therapy is called embolization. Classification There are different types of embolism, some of which are listed below. Embolism can be classified based on where it enters the circulation, either in ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Flow
Hemodynamics or haemodynamics are the dynamics of blood flow. The circulatory system is controlled by homeostatic mechanisms of autoregulation, just as hydraulic circuits are controlled by control systems. The hemodynamic response continuously monitors and adjusts to conditions in the body and its environment. Hemodynamics explains the physical laws that govern the flow of blood in the blood vessels. Blood flow ensures the transportation of nutrients, hormones, metabolic waste products, oxygen, and carbon dioxide throughout the body to maintain cell-level metabolism, the regulation of the pH, osmotic pressure and temperature of the whole body, and the protection from microbial and mechanical harm. Blood is a non-Newtonian fluid, and is most efficiently studied using rheology rather than hydrodynamics. Because blood vessels are not rigid tubes, classic hydrodynamics and fluids mechanics based on the use of classical viscometers are not capable of explaining haemodynamics. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma radiation (γ) * ''particle radiation'', such as alpha radiation (α), beta radiation (β), proton radiation and neutron radiation (particles of non-zero rest energy) * '' acoustic radiation'', such as ultrasound, sound, and seismic waves (dependent on a physical transmission medium) * ''gravitational wave, gravitational radiation'', that takes the form of gravitational waves, or ripples in the curvature of spacetime Radiation is often categorized as either ''ionizing radiation, ionizing'' or ''non-ionizing radiation, non-ionizing'' depending on the energy of the radiated particles. Ionizing radiation carries more than 10 electron volt, eV, which is enough to ionize atoms and molecules and break ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
