MRI, MRA Vocabulary
= Quantitative Cerebral Vessel Flow
Measure blood flow of vessel in cerebrum of brain.
= MRI: 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 waves to generate images of the organs in the body. URL: MRI
= MRA: magnetic resonance angiography
angiography: 血管攝影檢查
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. This is traditionally done by injecting a radio-opaque contrast agent into the blood vessel and imaging using X-ray based techniques such as fluoroscopy. URL: angiography
Magnetic resonance angiography–also called a magnetic resonance angiogram or MRA–is a type of MRI that looks specifically at the body's blood vessels. Unlike a traditional angiogram, which requires inserting a catheter into the body, magnetic resonance angiography is a far less invasive and less painful test. URL: MRA // Good read
catheter: A catheter is a soft hollow tube, which is passed into the bladder to drain urine. Catheters are sometimes necessary for people, who for a variety of reasons, cannot empty their bladder in the usual way, i.e. passing urine into a toilet or urinal.
= MR protocols
URL: MRI Protocols
= Hemodynamic
Hemodynamics or haemodynamics are the dynamics of blood flow. The circulatory system is controlled by homeostatic mechanisms, such as hydraulic circuits are controlled by control systems. Hemodynamic response continuously monitors and adjusts to conditions in the body and its environment. Thus hemodynamics explains the physical laws that govern the flow of blood in the blood vessels.
Blood flow ensures the transportation of nutrients, hormones, metabolic wastes, O2 and CO2 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 harms.[1]
Blood is a non-Newtonian fluid, best studied using rheology rather than hydrodynamics. Blood vessels are not rigid tubes, so classic hydrodynamics and fluids mechanics based on the use of classical viscometers are not capable of explaining hemodynamics.[2]
The study of the blood flow is called hemodynamics. The study of the properties of the blood flow is called hemorheology.
URL: Hemodynamic
- low flow status >> 5.5x greater risk of stroke in 12 mon.
= Vertebrobasilar disease
Vertebrobasilar disease is a disease of the arterial system. It describes a variety of conditions affecting blood flow to the back of the brain via the vertebral and/or basilar arteries.
Blood is delivered to several structures in the brain, particularly those responsible for movement and balance, via the carotid arteries (large vessels on each side of the neck) and vertebral arteries. The vertebral arteries are located at the back of the neck and merge at the base of the brain to form the basilar artery.
Causes and Risk Factors
Atherosclerosis or "hardening of the arteries" is the main cause of vertebrobasilar disease. The narrowing of the vertebral or basilar arteries caused by atherosclerosis creates vertebrobasilar insufficiency (VBI), or an insufficient delivery of blood flow to the posterior structures of the brain.
Patients with vertebrobasilar disease are at increased risk for transient ischemic attack (TIA) and stroke. Transient ischemic attack or "mini strokes" create stroke-like symptoms that resolve themselves in less than 24 hours. Strokes, however, that occur in this portion of the brain are particularly devastating and often result in death.
Vertebrobasilar disease is twice as common in men than women and typically occurs in the elderly. However, there is increased risk for earlier onset among people with risk factors relating to atherosclerotic disease including:
Diabetes, Hypertension, Obesity, High cholesterol, Smoking, Advanced age, Inactive lifestyle
Symptoms
As a result of decreased blood flow, and because vertebrobasilar disease affects so many separate structures of the brain, symptoms are varied and often referred to as a whole as vertebrobasilar insufficiency (VBI) or vertebral basilar ischemia (lack of blood flow to an organ).
Common symptoms include:
Vertigo (dizziness), Visual disturbances (blurring, graying, double vision), Sudden falls, Numbness or tingling, Slurred or lost speech, Confusion, Issues with swallowing,
Diagnosis
Diagnostic tests to confirm vertebrobasilar disease include magnetic resonance angiography or standard angiography, both of which use an injected dye to track the flow of blood and are useful in identifying areas of stenosis or narrowing within a blood vessel.
Treatment Options
The first step for an individual with vertebrobasilar disease is lifestyle modification, which includes exercise, smoking cessation, eating a low-cholesterol diet and controlling diabetes. Medications to help control cholesterol and platelet function may also be required, such as aspirin, Plavix™, Lipitor™ and Zocor™.
The Vertebral Artery Clinic at the University of Michigan Frankel Cardiovascular Center offers patients the full gamut of surgical and endovascular treatment options.
Surgical Options
Endarterectomy: The procedure involves the surgical removal of plaque from the affected artery
Bypass grafting
Vertebral artery reconstruction
Endovascular Options
Angioplasty and Stenting: Angioplasty is a procedure in which a catheter-guided balloon is used to open a narrowed coronary artery. A stent (a wire-mesh tube that expands to hold the artery open) is usually placed at the narrowed section during angioplasty.
URL: Vertebrobasilar disease
= Ischemic
Ischemia or ischaemia is a restriction in blood supply to tissues, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive).[3] Ischemia is generally caused by problems with blood vessels, with resultant damage to or dysfunction of tissue. It also means local anemia in a given part of a body sometimes resulting from constriction (such as vasoconstriction, thrombosis or embolism). Ischemia comprises not only insufficiency of oxygen, but also reduced availability of nutrients and inadequate removal of metabolic wastes. Ischemia can be partial (poor perfusion) or total. URL: Ischemic
= ischemic strokes
A transient ischemic attack (TIA) is a stroke that lasts only a few minutes. It happens when the blood supply to part of the brain is briefly blocked. Symptoms of a TIA are like other stroke symptoms, but do not last as long. They happen suddenly, and include
TIAs are often a warning sign for future strokes. Taking medicine, such as blood thinners, may reduce your risk of a stroke. Your doctor might also recommend surgery. You can also help lower your risk by having a healthy lifestyle. This includes not smoking, not drinking too much, eating a healthy diet, and exercising. It is also important to control other health problems, such as high blood pressure and cholesterol.
URL: Transient Ischemic Attack, Mini-stroke, TIA
= Hemorrhagic Stroke (Bleeds)
Hemorrhagic strokes make up about 13 percent of stroke cases. It’s caused by a weakened vessel that ruptures and bleeds into the surrounding brain. The blood accumulates and compresses the surrounding brain tissue.
The two types of hemorrhagic strokes are intracerebral (within the brain) hemorrhage or subarachnoid hemorrhage.
A hemorrhagic stroke occurs when a weakened blood vessel ruptures. Two types of weakened blood vessels usually cause hemorrhagic stroke: aneurysms and arteriovenous malformations (AVMs).
URL: Hemorrhagic Stroke (Bleeds)
= Intracerebral hemorrhage (ICH)
Overview
Intracerebral hemorrhage (ICH) is caused by bleeding within the brain tissue itself — a life-threatening type of stroke. A stroke occurs when the brain is deprived of oxygen and blood supply. ICH is most commonly caused by hypertension, arteriovenous malformations, or head trauma. Treatment focuses on stopping the bleeding, removing the blood clot (hematoma), and relieving the pressure on the brain.
What is an intracerebral hemorrhage (ICH)?
Tiny arteries bring blood to areas deep inside the brain (see Anatomy of the Brain). High blood pressure (hypertension) can cause these thin-walled arteries to rupture, releasing blood into the brain tissue. Enclosed within the rigid skull, clotted blood and fluid buildup increases pressure that can crush the brain against the bone or cause it to shift and herniate (Fig. 1). As blood spills into the brain, the area that artery supplied is now deprived of oxygen-rich blood – called a stroke. As blood cells within the clot die, toxins are released that further damage brain cells in the area surrounding the hematoma.
An ICH can occur close to the surface or in deep areas of the brain. Sometimes deep hemorrhages can expand into the ventricles – the fluid filled spaces in the center of the brain. Blockage of the normal cerebrospinal (CSF) circulation can enlarge the ventricles (hydrocephalus) causing confusion, lethargy, and loss of consciousness.
URL: Intracerebral hemorrhage (ICH)
= Subarachnoid hemorrhage
Subarachnoid hemorrhage (SAH) is a life-threatening type of stroke caused by bleeding into the space surrounding the brain. SAH can be caused by a ruptured aneurysm, AVM, or head injury. One-third of patients will survive with good recovery; one-third will survive with a disability; and one-third will die. Treatment focuses on stopping the bleeding, restoring normal blood flow, and preventing vasospasm.
What is a subarachnoid hemorrhage?
The subarachnoid space is the area between the brain and the skull. It is filled with cerebrospinal fluid (CSF), which acts as a floating cushion to protect the brain (see Anatomy of the Brain). When blood is released into the subarachnoid space, it irritates the lining of the brain, increases pressure on the brain, and damages brain cells. At the same time, the area of brain that previously received oxygen-rich blood from the affected artery is now deprived of blood, resulting in a stroke. SAH is frequently a sign of a ruptured aneurysm.
Enclosed within the rigid skull, clotted blood and fluid buildup increases pressure that can crush the brain against the bone or cause it to shift and herniate. Blockage of the normal CSF circulation can enlarge the ventricles (hydrocephalus), causing confusion, lethargy, and loss of consciousness.
Vasospasm is a common complication that may occur 5 to 10 days after SAH. Irritating blood byproducts cause the walls of an artery to contract and spasm. Vasospasm narrows the inside diameter (lumen) of the artery and thereby reduces blood flow to that region of the brain, causing a secondary stroke.
URL: subarachnoid hemorrhage
= Cerebrovascular condition
Cerebrovascular disease refers to a group of conditions, diseases, and disorders that affect the blood vessels and blood supply to the brain.
If a blockage, malformation, or hemorrhage prevents the brain cells from getting enough oxygen, brain damage can result.
Cerebrovascular disease can develop from a variety of causes, including atherosclerosis, where the arteries become narrow; thrombosis, or embolic arterial blood clot, which is a blood clot in an artery of the brain; or cerebral venous thrombosis, which is a blood clot in a vein of the brain.
Cerebrovascular diseases include stroke, transient ischemic attack (TIA), aneurysm, and vascular malformation.
In the United States, cerebrovascular disease is the fifth most commonTrusted Source cause of death. In 2017, it caused 44.9 fatalities per 100,000 people or 146,383 deaths in total.
URL: Cerebrovascular condition
= What is a carotid occlusion?
This narrowing is usually caused by the buildup of fatty substances and cholesterol deposits, called plaque. Carotid artery occlusion refers to complete blockage of the artery. When the carotid arteries are obstructed, you are at an increased risk for a stroke, the 5th leading cause of death in the U.S.
= stenosis
The abnormal narrowing of a passage in the body.
= occlusion
The blockage or closing of a blood vessel or hollow organ.
= Extracranial carotid stenosis/occlusion
• Intracranial stenosis/occlusion
The blockage or closing (narrowing) of a blood vessel or hollow organ.
• Arterial Dissection
An arterial dissection is a tear in the lining of an artery. When a tear occurs in a major artery in the head and neck — the carotid or vertebral arteries — that transmit blood to the brain, this is called a cerebral arterial dissection. The flow of blood between the layers of the torn blood vessel may cause the artery to narrow and even close off entirely. If this occurs, it could cause a stroke.
During a stroke, a blood vessel in the brain becomes blocked or bursts. Although strokes are more common in adults, they also occur in children. Arterial dissection is a leading cause of stroke in young people.
URL: Arterial Dissection
• Arteriovenous Malformation (AVM)
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 appear in any location. Although many AVMs are asymptomatic, they can cause intense pain or bleeding or lead to other serious medical problems.
AVMs are usually congenital and belong to the RASopathies. The genetic transmission patterns of AVMs are incomplete, but there are known genetic mutations (for instance in the epithelial line, tumor suppressor PTEN gene) which can lead to an increased occurrence throughout the body.
腦動靜脈血管畸形（英文：cerebral arteriovenous malformation，簡稱cAVM）是一種由於胚胎發育過程中的異常，造成腦部出現動靜脈血管直接連接的先天性畸形，主要病徵是腦部血管不正常聚集，使動脈內的血液不經微血管而直接注入靜脈，形成一種高流速及高壓力的血液短路，繼而增加腦內出血及中風的機會。
URL: Arteriovenous Malformation (AVM)
• Cerebral Venous Stenosis
Cerebral venous sinus thrombosis or stenosis (here collectively referred to as cerebral venous sinus occlusion, CVSO) can cause chronically-elevated intracranial pressure (ICP). Patients may have no neurological symptoms other than visual impairment, secondary to bilateral papilledema. Correctly recognizing these conditions, through proper ophthalmological examination and brain imaging, is very important to avoid delayed diagnosis and treatment.
URL: Cerebral Venous Stenosis
What is venous sinus stenosis?
It occurs when the pressure inside your brain (intracranial pressure) increases for no obvious reason. Patients often experience severe headaches and various visual symptoms. Some patients with IIH may have decreased blood flow through the cavities that drain blood out of the brain called dural venous sinus stenosis.
• Cerebral Aneurysm
A cerebral aneurysm (also called an intracranial aneurysm or brain aneurysm) is a bulging, weakened area in the wall of an artery in the brain, resulting in an abnormal widening, ballooning, or bleb. Because there is a weakened spot in the aneurysm wall, there is a risk for rupture (bursting) of the aneurysm.
A cerebral aneurysm more frequently occurs in an artery located in the front part of the brain that supplies oxygen-rich blood to the brain tissue. Arteries anywhere in the brain can develop aneurysms. A normal artery wall is made up of three layers. The aneurysm wall is thin and weak because of an abnormal loss or absence of the muscular layer of the artery wall, leaving only two layers.
The most common type of cerebral aneurysm is called a saccular, or berry, aneurysm, occurring in 90 percent of cerebral aneurysms. This type of aneurysm looks like a "berry" with a narrow stem. More than one aneurysm may be present.
URL: Cerebral Aneurysm
• Moyamoya Disease
Moyamoya disease is a rare, progressive cerebrovascular disorder caused by blocked arteries at the base of the brain in an area called the basal ganglia. The name “moyamoya” means “puff of smoke” in Japanese and describes the look of the tangle of tiny vessels formed to compensate for the blockage.
URL: Moyamoya Disease
= Circle of Willis
ACA (R/L): Anterior cerebral artery (Right/Left)
MCA (R/L): Middle cerebral artery (Right/Left)
PCA (R/L): Posterior cerebral artery (Right/Left)
ICA (R/L): Internal cartoid artery (Right/Left)
BA, BA2: Basilar artery
VA (R/L): Vertebral artery
Anterio communicating artery
Posterio communicating artery
URL: Brain Artery Map
= Cerebral Arteries
The cerebral arteries describe three main pairs of arteries and their branches, which perfuse the cerebrum of the brain. The three main arteries are the:
Anterior cerebral artery (ACA)
Middle cerebral artery (MCA)
Posterior cerebral artery (PCA)
Both the ACA and MCA originate from the cerebral portion of internal carotid artery, while PCA branches from the intersection of the posterior communicating artery and the anterior portion of the basilar artery. The three pairs of arteries are linked via the anterior communicating artery and the posterior communicating arteries. All three arteries send out arteries that perforate brain in the medial central portions prior to branching and bifurcating further.
The arteries are usually divided into different segments from 1–4 or 5 to denote how far the level of the branch with the lower numbers denoting vessels closer to the source artery. Even though the arteries branching off these vessels retain some aspect of constancy in terms of size and position, a great amount of variety in topography, position, source and prominence nevertheless exists.
URL: Cerebral Arteries
URL: Brain Artery Map
Q?: Does the baseline take region/race into consideration?
= Velocity Encoding (VENC)
VENC stands for velocity encoding, a parameter that must be specified before performing a phase-contrast (PC) MRI or MRA study. VENC, measured in cm/sec, should be chosen to encompass the highest velocities likely to be encountered within the vessel of interest. If VENC is set to 50 cm/sec, for example, flows in the range of ±50 cm/sec can be accurately represented by a set of phase shifts spanning from −180° to +180°. The VENC parameter adjusts the strength of the bipolar gradients so that the maximum velocity selected corresponds to a 180° phase shift in the data. VENC is inversely related to the size of these gradients. Larger gradients create more dephasing and correspond to smaller values of VENC. The VENC setting is critical for proper performance of the PC pulse sequence, but usually can only be estimated since its optimal value is generally not known in advance. Often a study will be repeated using 2-3 different VENCs based on typical velocities expected. If the selected VENC is set too high, the range of flows imaged will span only a limited phase shift range. The signal-to-noise of the image and quality of the data will suffer. Small velocity differences on flow studies will not be distinguishable, and vessels with slow flow may be impossible to see. If VENC is picked too low, velocity aliasing may occur with faster flows not being appropriately represented. For example, if the chosen value of VENC is 50 cm/sec, the bipolar gradient is adjusted so that a flows of +25 and +50 cm/sec are assigned a phases of +90° and +180° respectively. If the actual velocity is +75 cm/sec, this flow will be mapped to +270°, a value that cannot be distinguished from a phase shift of −90°. Instead of representing the +75-cm/sec flow as its actual velocity, the computer will assign it a flow of 25 cm/sec in the opposite direction!
URL: Velocity aliasing occurs when VENC is set too low
URL: VENC note
Velocity aliasing occurs when VENC is set too low.
PC study of pulmonary artery with VENC set too low (15 cm/sec). Note velocity aliasing (white areas) which appears to be flow in the wrong direction.
URL: VENC set too low
PC study of pulmonary artery with VENC set properly (30 cm/sec). The vessel is properly displayed as black with velocity aliasing no longer apparent.
Velocity Encoding (VENC)
= Diamox Map
I think this is brain image after taking Diamox.
URL: Diamox Map
= FDA 510(k) Cleared Medical Device
A 510(K) is a premarket submission made to FDA to demonstrate that the device to be marketed is at least as safe and effective, that is, substantially equivalent, to a legally marketed device (21 CFR §807.92(a)(3)) that is not subject to premarket approval.
- Low flow patient > higher risk of recurrent event with the lowering of their blood pressresure (<140/90).
= Carotid occlusion
Unilateral means 1. (of an action or decision) performed by or affecting only one person, group, or country involved in a situation, without the agreement of another or the others. ex: "unilateral nuclear disarmament" 2. relating to or affecting only one side of an organ, the body, or another structure. ex: "unilateral cerebral lesions"
= Adequacy of collateral flow
Overview of Neuroimaging of Stroke
K. Malhotra, D.S. Liebeskind, in Primer on Cerebrovascular Diseases (Second Edition), 2017
Imaging Modalities to Assess Collateral Circulation
Collateral blood flow refers to the potential vigorous network of vessels that play a major role in patients with ischemic stroke. It provides perfusion to the penumbral region reducing the progression of infarct size and thus improves clinical outcome with reperfusion therapies. Noninvasive imaging techniques provide real-time evaluation of various aspects of this robust collateral arterial supply. CTA is a more commonly used technique than MRA to assess the collateral status by direct comparison with the contralateral hemisphere or thorough visual inspection of the number of MCA subdivisions enhanced with intravenous contrast. Multiphase CTA has emerged as an important imaging technique to investigate collateral status in patients who are perfusion dependent.
Similar to CTA, MRA also evaluates collateral status using noninvasive vessel analysis and provides detailed data on collateral flow. As mentioned earlier, FLAIR vascular hyperintensities reflect slow retrograde collateral flow distal to the arterial occlusion, providing information on the extent of leptomeningeal collaterals. Flow diversion into the ipsilateral anterior cerebral artery (ACA) or PCA on MRA may also be indirect markers of collateral support to the ischemic MCA territory. Such presence of adequate collateral flow at initial presentation provides detailed information on auxiliary vascular flow to the ischemic area and further guides clinicians for therapeutic decisions including endovascular procedures.
penumbra /pɪˈnʌmbrə/ noun
1. the partially shaded outer region of the shadow cast by an opaque object.
2. a peripheral or indeterminate area or group.
"an immense penumbra of theory surrounds any observation"
URL: Collateral Circulation
= cerebrovascular reserve
Carotid Occlusion Surgery
revascularization with EC-IC bypass
Extracranial carotid stenosis
distal flow status
collateral flow
NASCET criteria
carotid stenosis patients
asymptomatic patients
Intracranial Stenosis
stenotic vessel
- NOVA is used to evaluate the hemodynamic effects of intracranial stenosis; to quantify
blood flow in the stenotic vessel pre and post intervention and to assess the effectiveness
of treatment.
in-stent stenosis
anti platelet therapy
angiograms
arterial dissection
anti platelet therapy
- Serial measurements with NOVA corroborate anatomic imaging showing that the dissection has healed and that flow has normalized, allowing physicians to adjust anti-platelet medication according to the needs of the individual patient.
staged embolization and surgical resection
AVMs are complex cerebrovascular disorders
Cerebral Venous Stenosis
Cerebral aneurysm
stent assisted coiling
Moyamoya Disease
- MM disease is a vasculopathy in which the major arteries of the brain progressively close off.
morphology
VERiTAS flow algorithm
Measure blood flow of vessel in cerebrum of brain.
= MRI: 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 waves to generate images of the organs in the body. URL: MRI
= MRA: magnetic resonance angiography
angiography: 血管攝影檢查
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. This is traditionally done by injecting a radio-opaque contrast agent into the blood vessel and imaging using X-ray based techniques such as fluoroscopy. URL: angiography
Magnetic resonance angiography–also called a magnetic resonance angiogram or MRA–is a type of MRI that looks specifically at the body's blood vessels. Unlike a traditional angiogram, which requires inserting a catheter into the body, magnetic resonance angiography is a far less invasive and less painful test. URL: MRA // Good read
catheter: A catheter is a soft hollow tube, which is passed into the bladder to drain urine. Catheters are sometimes necessary for people, who for a variety of reasons, cannot empty their bladder in the usual way, i.e. passing urine into a toilet or urinal.
= MR protocols
URL: MRI Protocols
= Hemodynamic
Hemodynamics or haemodynamics are the dynamics of blood flow. The circulatory system is controlled by homeostatic mechanisms, such as hydraulic circuits are controlled by control systems. Hemodynamic response continuously monitors and adjusts to conditions in the body and its environment. Thus hemodynamics explains the physical laws that govern the flow of blood in the blood vessels.
Blood flow ensures the transportation of nutrients, hormones, metabolic wastes, O2 and CO2 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 harms.[1]
Blood is a non-Newtonian fluid, best studied using rheology rather than hydrodynamics. Blood vessels are not rigid tubes, so classic hydrodynamics and fluids mechanics based on the use of classical viscometers are not capable of explaining hemodynamics.[2]
The study of the blood flow is called hemodynamics. The study of the properties of the blood flow is called hemorheology.
URL: Hemodynamic
- low flow status >> 5.5x greater risk of stroke in 12 mon.
= Vertebrobasilar disease
Vertebrobasilar disease is a disease of the arterial system. It describes a variety of conditions affecting blood flow to the back of the brain via the vertebral and/or basilar arteries.
Blood is delivered to several structures in the brain, particularly those responsible for movement and balance, via the carotid arteries (large vessels on each side of the neck) and vertebral arteries. The vertebral arteries are located at the back of the neck and merge at the base of the brain to form the basilar artery.
Causes and Risk Factors
Atherosclerosis or "hardening of the arteries" is the main cause of vertebrobasilar disease. The narrowing of the vertebral or basilar arteries caused by atherosclerosis creates vertebrobasilar insufficiency (VBI), or an insufficient delivery of blood flow to the posterior structures of the brain.
Patients with vertebrobasilar disease are at increased risk for transient ischemic attack (TIA) and stroke. Transient ischemic attack or "mini strokes" create stroke-like symptoms that resolve themselves in less than 24 hours. Strokes, however, that occur in this portion of the brain are particularly devastating and often result in death.
Vertebrobasilar disease is twice as common in men than women and typically occurs in the elderly. However, there is increased risk for earlier onset among people with risk factors relating to atherosclerotic disease including:
Diabetes, Hypertension, Obesity, High cholesterol, Smoking, Advanced age, Inactive lifestyle
Symptoms
As a result of decreased blood flow, and because vertebrobasilar disease affects so many separate structures of the brain, symptoms are varied and often referred to as a whole as vertebrobasilar insufficiency (VBI) or vertebral basilar ischemia (lack of blood flow to an organ).
Common symptoms include:
Vertigo (dizziness), Visual disturbances (blurring, graying, double vision), Sudden falls, Numbness or tingling, Slurred or lost speech, Confusion, Issues with swallowing,
Diagnosis
Diagnostic tests to confirm vertebrobasilar disease include magnetic resonance angiography or standard angiography, both of which use an injected dye to track the flow of blood and are useful in identifying areas of stenosis or narrowing within a blood vessel.
Treatment Options
The first step for an individual with vertebrobasilar disease is lifestyle modification, which includes exercise, smoking cessation, eating a low-cholesterol diet and controlling diabetes. Medications to help control cholesterol and platelet function may also be required, such as aspirin, Plavix™, Lipitor™ and Zocor™.
The Vertebral Artery Clinic at the University of Michigan Frankel Cardiovascular Center offers patients the full gamut of surgical and endovascular treatment options.
Surgical Options
Endarterectomy: The procedure involves the surgical removal of plaque from the affected artery
Bypass grafting
Vertebral artery reconstruction
Endovascular Options
Angioplasty and Stenting: Angioplasty is a procedure in which a catheter-guided balloon is used to open a narrowed coronary artery. A stent (a wire-mesh tube that expands to hold the artery open) is usually placed at the narrowed section during angioplasty.
URL: Vertebrobasilar disease
= Ischemic
Ischemia or ischaemia is a restriction in blood supply to tissues, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive).[3] Ischemia is generally caused by problems with blood vessels, with resultant damage to or dysfunction of tissue. It also means local anemia in a given part of a body sometimes resulting from constriction (such as vasoconstriction, thrombosis or embolism). Ischemia comprises not only insufficiency of oxygen, but also reduced availability of nutrients and inadequate removal of metabolic wastes. Ischemia can be partial (poor perfusion) or total. URL: Ischemic
= ischemic strokes
A transient ischemic attack (TIA) is a stroke that lasts only a few minutes. It happens when the blood supply to part of the brain is briefly blocked. Symptoms of a TIA are like other stroke symptoms, but do not last as long. They happen suddenly, and include
- Numbness or weakness, especially on one side of the body
- Confusion or trouble speaking or understanding speech
- Trouble seeing in one or both eyes
- Difficulty walking
- Dizziness
- Loss of balance or coordination
TIAs are often a warning sign for future strokes. Taking medicine, such as blood thinners, may reduce your risk of a stroke. Your doctor might also recommend surgery. You can also help lower your risk by having a healthy lifestyle. This includes not smoking, not drinking too much, eating a healthy diet, and exercising. It is also important to control other health problems, such as high blood pressure and cholesterol.
URL: Transient Ischemic Attack, Mini-stroke, TIA
= Hemorrhagic Stroke (Bleeds)
Hemorrhagic strokes make up about 13 percent of stroke cases. It’s caused by a weakened vessel that ruptures and bleeds into the surrounding brain. The blood accumulates and compresses the surrounding brain tissue.
The two types of hemorrhagic strokes are intracerebral (within the brain) hemorrhage or subarachnoid hemorrhage.
A hemorrhagic stroke occurs when a weakened blood vessel ruptures. Two types of weakened blood vessels usually cause hemorrhagic stroke: aneurysms and arteriovenous malformations (AVMs).
URL: Hemorrhagic Stroke (Bleeds)
= Intracerebral hemorrhage (ICH)
Overview
Intracerebral hemorrhage (ICH) is caused by bleeding within the brain tissue itself — a life-threatening type of stroke. A stroke occurs when the brain is deprived of oxygen and blood supply. ICH is most commonly caused by hypertension, arteriovenous malformations, or head trauma. Treatment focuses on stopping the bleeding, removing the blood clot (hematoma), and relieving the pressure on the brain.
What is an intracerebral hemorrhage (ICH)?
Tiny arteries bring blood to areas deep inside the brain (see Anatomy of the Brain). High blood pressure (hypertension) can cause these thin-walled arteries to rupture, releasing blood into the brain tissue. Enclosed within the rigid skull, clotted blood and fluid buildup increases pressure that can crush the brain against the bone or cause it to shift and herniate (Fig. 1). As blood spills into the brain, the area that artery supplied is now deprived of oxygen-rich blood – called a stroke. As blood cells within the clot die, toxins are released that further damage brain cells in the area surrounding the hematoma.
An ICH can occur close to the surface or in deep areas of the brain. Sometimes deep hemorrhages can expand into the ventricles – the fluid filled spaces in the center of the brain. Blockage of the normal cerebrospinal (CSF) circulation can enlarge the ventricles (hydrocephalus) causing confusion, lethargy, and loss of consciousness.
URL: Intracerebral hemorrhage (ICH)
= Subarachnoid hemorrhage
Subarachnoid hemorrhage (SAH) is a life-threatening type of stroke caused by bleeding into the space surrounding the brain. SAH can be caused by a ruptured aneurysm, AVM, or head injury. One-third of patients will survive with good recovery; one-third will survive with a disability; and one-third will die. Treatment focuses on stopping the bleeding, restoring normal blood flow, and preventing vasospasm.
What is a subarachnoid hemorrhage?
The subarachnoid space is the area between the brain and the skull. It is filled with cerebrospinal fluid (CSF), which acts as a floating cushion to protect the brain (see Anatomy of the Brain). When blood is released into the subarachnoid space, it irritates the lining of the brain, increases pressure on the brain, and damages brain cells. At the same time, the area of brain that previously received oxygen-rich blood from the affected artery is now deprived of blood, resulting in a stroke. SAH is frequently a sign of a ruptured aneurysm.
Enclosed within the rigid skull, clotted blood and fluid buildup increases pressure that can crush the brain against the bone or cause it to shift and herniate. Blockage of the normal CSF circulation can enlarge the ventricles (hydrocephalus), causing confusion, lethargy, and loss of consciousness.
Vasospasm is a common complication that may occur 5 to 10 days after SAH. Irritating blood byproducts cause the walls of an artery to contract and spasm. Vasospasm narrows the inside diameter (lumen) of the artery and thereby reduces blood flow to that region of the brain, causing a secondary stroke.
URL: subarachnoid hemorrhage
= Cerebrovascular condition
Cerebrovascular disease refers to a group of conditions, diseases, and disorders that affect the blood vessels and blood supply to the brain.
If a blockage, malformation, or hemorrhage prevents the brain cells from getting enough oxygen, brain damage can result.
Cerebrovascular disease can develop from a variety of causes, including atherosclerosis, where the arteries become narrow; thrombosis, or embolic arterial blood clot, which is a blood clot in an artery of the brain; or cerebral venous thrombosis, which is a blood clot in a vein of the brain.
Cerebrovascular diseases include stroke, transient ischemic attack (TIA), aneurysm, and vascular malformation.
In the United States, cerebrovascular disease is the fifth most commonTrusted Source cause of death. In 2017, it caused 44.9 fatalities per 100,000 people or 146,383 deaths in total.
URL: Cerebrovascular condition
= What is a carotid occlusion?
This narrowing is usually caused by the buildup of fatty substances and cholesterol deposits, called plaque. Carotid artery occlusion refers to complete blockage of the artery. When the carotid arteries are obstructed, you are at an increased risk for a stroke, the 5th leading cause of death in the U.S.
= stenosis
The abnormal narrowing of a passage in the body.
= occlusion
The blockage or closing of a blood vessel or hollow organ.
= Extracranial carotid stenosis/occlusion
• Intracranial stenosis/occlusion
The blockage or closing (narrowing) of a blood vessel or hollow organ.
• Arterial Dissection
An arterial dissection is a tear in the lining of an artery. When a tear occurs in a major artery in the head and neck — the carotid or vertebral arteries — that transmit blood to the brain, this is called a cerebral arterial dissection. The flow of blood between the layers of the torn blood vessel may cause the artery to narrow and even close off entirely. If this occurs, it could cause a stroke.
During a stroke, a blood vessel in the brain becomes blocked or bursts. Although strokes are more common in adults, they also occur in children. Arterial dissection is a leading cause of stroke in young people.
URL: Arterial Dissection
• Arteriovenous Malformation (AVM)
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 appear in any location. Although many AVMs are asymptomatic, they can cause intense pain or bleeding or lead to other serious medical problems.
AVMs are usually congenital and belong to the RASopathies. The genetic transmission patterns of AVMs are incomplete, but there are known genetic mutations (for instance in the epithelial line, tumor suppressor PTEN gene) which can lead to an increased occurrence throughout the body.
腦動靜脈血管畸形（英文：cerebral arteriovenous malformation，簡稱cAVM）是一種由於胚胎發育過程中的異常，造成腦部出現動靜脈血管直接連接的先天性畸形，主要病徵是腦部血管不正常聚集，使動脈內的血液不經微血管而直接注入靜脈，形成一種高流速及高壓力的血液短路，繼而增加腦內出血及中風的機會。
URL: Arteriovenous Malformation (AVM)
• Cerebral Venous Stenosis
Cerebral venous sinus thrombosis or stenosis (here collectively referred to as cerebral venous sinus occlusion, CVSO) can cause chronically-elevated intracranial pressure (ICP). Patients may have no neurological symptoms other than visual impairment, secondary to bilateral papilledema. Correctly recognizing these conditions, through proper ophthalmological examination and brain imaging, is very important to avoid delayed diagnosis and treatment.
URL: Cerebral Venous Stenosis
What is venous sinus stenosis?
It occurs when the pressure inside your brain (intracranial pressure) increases for no obvious reason. Patients often experience severe headaches and various visual symptoms. Some patients with IIH may have decreased blood flow through the cavities that drain blood out of the brain called dural venous sinus stenosis.
• Cerebral Aneurysm
A cerebral aneurysm (also called an intracranial aneurysm or brain aneurysm) is a bulging, weakened area in the wall of an artery in the brain, resulting in an abnormal widening, ballooning, or bleb. Because there is a weakened spot in the aneurysm wall, there is a risk for rupture (bursting) of the aneurysm.
A cerebral aneurysm more frequently occurs in an artery located in the front part of the brain that supplies oxygen-rich blood to the brain tissue. Arteries anywhere in the brain can develop aneurysms. A normal artery wall is made up of three layers. The aneurysm wall is thin and weak because of an abnormal loss or absence of the muscular layer of the artery wall, leaving only two layers.
The most common type of cerebral aneurysm is called a saccular, or berry, aneurysm, occurring in 90 percent of cerebral aneurysms. This type of aneurysm looks like a "berry" with a narrow stem. More than one aneurysm may be present.
URL: Cerebral Aneurysm
• Moyamoya Disease
Moyamoya disease is a rare, progressive cerebrovascular disorder caused by blocked arteries at the base of the brain in an area called the basal ganglia. The name “moyamoya” means “puff of smoke” in Japanese and describes the look of the tangle of tiny vessels formed to compensate for the blockage.
URL: Moyamoya Disease
= Circle of Willis
ACA (R/L): Anterior cerebral artery (Right/Left)
MCA (R/L): Middle cerebral artery (Right/Left)
PCA (R/L): Posterior cerebral artery (Right/Left)
ICA (R/L): Internal cartoid artery (Right/Left)
BA, BA2: Basilar artery
VA (R/L): Vertebral artery
Anterio communicating artery
Posterio communicating artery
URL: Brain Artery Map
= Cerebral Arteries
The cerebral arteries describe three main pairs of arteries and their branches, which perfuse the cerebrum of the brain. The three main arteries are the:
Anterior cerebral artery (ACA)
Middle cerebral artery (MCA)
Posterior cerebral artery (PCA)
Both the ACA and MCA originate from the cerebral portion of internal carotid artery, while PCA branches from the intersection of the posterior communicating artery and the anterior portion of the basilar artery. The three pairs of arteries are linked via the anterior communicating artery and the posterior communicating arteries. All three arteries send out arteries that perforate brain in the medial central portions prior to branching and bifurcating further.
The arteries are usually divided into different segments from 1–4 or 5 to denote how far the level of the branch with the lower numbers denoting vessels closer to the source artery. Even though the arteries branching off these vessels retain some aspect of constancy in terms of size and position, a great amount of variety in topography, position, source and prominence nevertheless exists.
URL: Cerebral Arteries
URL: Brain Artery Map
Q?: Does the baseline take region/race into consideration?
= Velocity Encoding (VENC)
VENC stands for velocity encoding, a parameter that must be specified before performing a phase-contrast (PC) MRI or MRA study. VENC, measured in cm/sec, should be chosen to encompass the highest velocities likely to be encountered within the vessel of interest. If VENC is set to 50 cm/sec, for example, flows in the range of ±50 cm/sec can be accurately represented by a set of phase shifts spanning from −180° to +180°. The VENC parameter adjusts the strength of the bipolar gradients so that the maximum velocity selected corresponds to a 180° phase shift in the data. VENC is inversely related to the size of these gradients. Larger gradients create more dephasing and correspond to smaller values of VENC. The VENC setting is critical for proper performance of the PC pulse sequence, but usually can only be estimated since its optimal value is generally not known in advance. Often a study will be repeated using 2-3 different VENCs based on typical velocities expected. If the selected VENC is set too high, the range of flows imaged will span only a limited phase shift range. The signal-to-noise of the image and quality of the data will suffer. Small velocity differences on flow studies will not be distinguishable, and vessels with slow flow may be impossible to see. If VENC is picked too low, velocity aliasing may occur with faster flows not being appropriately represented. For example, if the chosen value of VENC is 50 cm/sec, the bipolar gradient is adjusted so that a flows of +25 and +50 cm/sec are assigned a phases of +90° and +180° respectively. If the actual velocity is +75 cm/sec, this flow will be mapped to +270°, a value that cannot be distinguished from a phase shift of −90°. Instead of representing the +75-cm/sec flow as its actual velocity, the computer will assign it a flow of 25 cm/sec in the opposite direction!
URL: Velocity aliasing occurs when VENC is set too low
URL: VENC note
Velocity aliasing occurs when VENC is set too low.
PC study of pulmonary artery with VENC set too low (15 cm/sec). Note velocity aliasing (white areas) which appears to be flow in the wrong direction.
URL: VENC set too low
PC study of pulmonary artery with VENC set properly (30 cm/sec). The vessel is properly displayed as black with velocity aliasing no longer apparent.
Velocity Encoding (VENC)
= Diamox Map
I think this is brain image after taking Diamox.
URL: Diamox Map
= FDA 510(k) Cleared Medical Device
A 510(K) is a premarket submission made to FDA to demonstrate that the device to be marketed is at least as safe and effective, that is, substantially equivalent, to a legally marketed device (21 CFR §807.92(a)(3)) that is not subject to premarket approval.
- Low flow patient > higher risk of recurrent event with the lowering of their blood pressresure (<140/90).
= Carotid occlusion
Carotid occlusive disease, also called carotid stenosis, is a condition in which one or both of the carotid arteries becomes narrowed or blocked. It is a serious condition that increases the risk of stroke if left untreated.
The carotid arteries are located on either side of the neck — you can feel your pulse quite strongly there by pressing your fingers against your neck below your jaw, to the side of your voice box. Just above the pulse point, the carotid artery branches into two smaller vessels, called the internal and external carotid arteries. Healthy, unobstructed carotid arteries are the critical pathways that supply freshly oxygenated blood from the heart to the brain. When those arteries become narrowed or blocked by plaque, not enough oxygen gets to the brain. The plaque may also break off into small pieces (emboli) that can travel into smaller vessels in the brain and lead to stroke. The area where the main carotid artery branches is a common location for a blockage.
If an artery becomes completely blocked (which is called carotid occlusion) or if piece of the blockage breaks off and travels to a smaller vessel where it completely blocks blood flow, a part of the brain may be completely deprived of oxygen, leading to the destruction of brain tissue. This is what happens during the event we call a stroke, or a “brain attack.” There are nearly half a million strokes each year in the United States, and it’s the third leading cause of death. Stroke claims 140,000 American lives a year — and half of those fatal strokes can be traced to carotid occlusion.
A partial blockage, where one of both carotid arteries becomes narrowed, is called carotid stenosis. The carotid arteries are large enough to allow good short-term blood supply even when they start to narrow, and other arteries sometimes expand to compensate for the reduced flow, but carotid stenosis can still cause a stroke or a transient ischemic attack (TIA). The larger danger of carotid stenosis is that a piece of the atherosclerotic plaque will break off and completely block an artery in the brain, which can also result in a stroke or TIA. A TIA, sometimes called a “mini-stroke,” can cause temporary neurological deficits and is an indicator of an increased risk of a future stroke. A mini-stroke is often small enough to be overlooked or dismissed, but it’s a warning sign that should not be ignored. (See Symptoms of Carotid Occlusive Disease.)
= Unilateral carotid occlusionUnilateral means 1. (of an action or decision) performed by or affecting only one person, group, or country involved in a situation, without the agreement of another or the others. ex: "unilateral nuclear disarmament" 2. relating to or affecting only one side of an organ, the body, or another structure. ex: "unilateral cerebral lesions"
= Adequacy of collateral flow
Overview of Neuroimaging of Stroke
K. Malhotra, D.S. Liebeskind, in Primer on Cerebrovascular Diseases (Second Edition), 2017
Imaging Modalities to Assess Collateral Circulation
Collateral blood flow refers to the potential vigorous network of vessels that play a major role in patients with ischemic stroke. It provides perfusion to the penumbral region reducing the progression of infarct size and thus improves clinical outcome with reperfusion therapies. Noninvasive imaging techniques provide real-time evaluation of various aspects of this robust collateral arterial supply. CTA is a more commonly used technique than MRA to assess the collateral status by direct comparison with the contralateral hemisphere or thorough visual inspection of the number of MCA subdivisions enhanced with intravenous contrast. Multiphase CTA has emerged as an important imaging technique to investigate collateral status in patients who are perfusion dependent.
Similar to CTA, MRA also evaluates collateral status using noninvasive vessel analysis and provides detailed data on collateral flow. As mentioned earlier, FLAIR vascular hyperintensities reflect slow retrograde collateral flow distal to the arterial occlusion, providing information on the extent of leptomeningeal collaterals. Flow diversion into the ipsilateral anterior cerebral artery (ACA) or PCA on MRA may also be indirect markers of collateral support to the ischemic MCA territory. Such presence of adequate collateral flow at initial presentation provides detailed information on auxiliary vascular flow to the ischemic area and further guides clinicians for therapeutic decisions including endovascular procedures.
penumbra /pɪˈnʌmbrə/ noun
1. the partially shaded outer region of the shadow cast by an opaque object.
2. a peripheral or indeterminate area or group.
"an immense penumbra of theory surrounds any observation"
URL: Collateral Circulation
= cerebrovascular reserve
Carotid Occlusion Surgery
revascularization with EC-IC bypass
Extracranial carotid stenosis
distal flow status
collateral flow
NASCET criteria
carotid stenosis patients
asymptomatic patients
Intracranial Stenosis
stenotic vessel
- NOVA is used to evaluate the hemodynamic effects of intracranial stenosis; to quantify
blood flow in the stenotic vessel pre and post intervention and to assess the effectiveness
of treatment.
in-stent stenosis
anti platelet therapy
angiograms
arterial dissection
anti platelet therapy
- Serial measurements with NOVA corroborate anatomic imaging showing that the dissection has healed and that flow has normalized, allowing physicians to adjust anti-platelet medication according to the needs of the individual patient.
staged embolization and surgical resection
AVMs are complex cerebrovascular disorders
Cerebral Venous Stenosis
Cerebral aneurysm
stent assisted coiling
Moyamoya Disease
- MM disease is a vasculopathy in which the major arteries of the brain progressively close off.
morphology
VERiTAS flow algorithm
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