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Too little blood flow results if blood flow to the brain is below 18 to 20 ml per 100 g per minute, and tissue death occurs if flow dips below 8 to 10 ml per 100 g per minute. In brain tissue, a biochemical cascade known as the ischemic cascade is triggered when the tissue becomes ischemic, potentially resulting in damage to and the death of ...
Arterial spin labeling (ASL), also known as arterial spin tagging, is a magnetic resonance imaging technique used to quantify cerebral blood perfusion by labelling blood water as it flows throughout the brain. ASL specifically refers to magnetic labeling of arterial blood below or in the imaging slab, without the need of gadolinium contrast. [1]
The ischemic (ischaemic) cascade is a series of biochemical reactions that are initiated in the brain and other aerobic tissues after seconds to minutes of ischemia (inadequate blood supply). [1] This is typically secondary to stroke , injury, or cardiac arrest due to heart attack .
Once the desired blood vessel is found, blood flow velocities may be measured with a pulsed Doppler effect probe, which graphs velocities over time. Together, these make a duplex test . The second method of recording uses only the second probe function, relying instead on the training and experience of the clinician in finding the correct vessels.
The majority of the CSF is formed in the choroid plexus and flows through the brain along a distinct pathway: moving through the cerebral ventricular system, into the subarachnoid space surrounding the brain, then draining into the systemic blood column via arachnoid granulations of the dural sinuses or to peripheral lymphatics along cranial ...
By means of cerebral autoregulation, the body is able to deliver sufficient blood containing oxygen and nutrients to the brain tissue for this metabolic need, and remove CO 2 and other waste products. Cerebral autoregulation refers to the physiological mechanisms that maintain blood flow at an appropriate level during changes in blood pressure ...
Changes in brain activity are closely coupled with changes in blood flow in those areas, and knowing this has proved useful in mapping brain functions in humans. The measurement of haemodynamic response, in a clinical setting, can be used to create images of the brain in which especially active and inactive regions are shown as distinct from ...
[1] [2] This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases. [3] The primary form of fMRI uses the blood-oxygen-level dependent (BOLD) contrast, [4] discovered by Seiji Ogawa in 1990.