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Fluid-attenuated inversion recovery (FLAIR) is a magnetic resonance imaging sequence with an inversion recovery set to null fluids. For example, it can be used in brain imaging to suppress cerebrospinal fluid (CSF) effects on the image, so as to bring out the periventricular hyperintense lesions, such as multiple sclerosis (MS) plaques. [ 1 ]
Fluid-attenuated inversion recovery (FLAIR) [2] is an inversion-recovery pulse sequence used to nullify the signal from fluids. For example, it can be used in brain imaging to suppress cerebrospinal fluid so as to bring out periventricular hyperintense lesions, such as multiple sclerosis plaques.
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]
In analysis of the fetal brain, MRI provides more information about gyration than ultrasound. [24] MRI is sensitive for the detection of brain abscess. [25] A number of different imaging modalities or sequences can be used with imaging the nervous system: T 1-weighted (T1W) images: Cerebrospinal fluid is dark.
Demyelinating lesions begin with the appearance of some areas named NAWM (normal appearing white matter) which despite its name, is abnormal in several parameters. These areas show axonal transections and stressed oligodendrocytes (the cells responsible for maintaining the myelin), and randomly, they show clusters of activated microglia named ...
Most of the brain in MS is unaffected. Though obviously normal white matter appears normal under MRI, so does the NAWM white matter described in the next section. To establish a difference, normal white matter is named Non-lesional white matter (NLWM) [134] This normal white matter is reported to be around 56% of the total WM of the patients. [135]
The key to Phase-contrast MRI (PC-MRI) is the use of a bipolar gradient. [4] A bipolar gradient has equal positive and negative magnitudes that are applied for the same time duration. The bipolar gradient in PC-MRI is put in a sequence after RF excitation but before data collection during the echo time of the generic MRI modality.
MRI scans showing hyperintensities. A hyperintensity or T2 hyperintensity is an area of high intensity on types of magnetic resonance imaging (MRI) scans of the brain of a human or of another mammal that reflect lesions produced largely by demyelination and axonal loss.