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The study of CSF flow became one of Phase-contrast MRI's major applications. 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.
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] It was invented by Graeme Bydder, Joseph Hajnal, and Ian Young in the early 1990s. [2]
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.
T2*-weighted imaging of the brain 26 weeks after subarachnoid hemorrhage, showing hemosiderin deposits as hypointense areas. [1] T 2 *-weighted imaging is an MRI sequence to quantify observable or effective T 2 (T2* or "T2-star"). In this sequence, hemorrhages and hemosiderin deposits become hypointense. [2]
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.
DWI is most applicable when the tissue of interest is dominated by isotropic water movement e.g. grey matter in the cerebral cortex and major brain nuclei, or in the body—where the diffusion rate appears to be the same when measured along any axis. However, DWI also remains sensitive to T1 and T2 relaxation.
SWI Image acquired at 4 Tesla showing the veins in the brain. Susceptibility weighted imaging (SWI), originally called BOLD venographic imaging, is an MRI sequence that is exquisitely sensitive to venous blood, hemorrhage and iron storage. SWI uses a fully flow compensated, long echo, gradient recalled echo (GRE) pulse sequence to
Phase contrast MRI (PC-MRI) is used to measure flow velocities in the body. It is used mainly to measure blood flow in the heart and throughout the body. PC-MRI may be considered a method of magnetic resonance velocimetry. Since modern PC-MRI typically is time-resolved, it also may be referred to as 4-D imaging (three spatial dimensions plus ...