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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 ]
DWI directly visualizes the ischemic necrosis in cerebral infarction in the form of a cytotoxic edema, [38] appearing as a high DWI signal within minutes of arterial occlusion. [39] With perfusion MRI detecting both the infarcted core and the salvageable penumbra, the latter can be quantified by DWI and perfusion MRI. [40]
Inversion recovery is a magnetic resonance imaging sequence that provides high contrast between tissue and lesion. It can be used to provide high T1 weighted image, high T2 weighted image, and to suppress the signals from fat , blood , or cerebrospinal fluid (CSF).
Diffusion-weighted images (DWI): DWI uses the diffusion of water molecules to generate contrast in MR images. Proton density (PD) images: CSF has a relatively high level of protons, making CSF appear bright. Gray matter is brighter than white matter. [27] False color MRI by applying red to T1, green to PD and blue to T2.
MRI Scanner Mark One. The first MRI scanner to be built and used, in Aberdeen Royal Infirmary in Scotland. The history of magnetic resonance imaging (MRI) includes the work of many researchers who contributed to the discovery of nuclear magnetic resonance (NMR) and described the underlying physics of magnetic resonance imaging, starting early in the twentieth century.
Functional magnetic resonance imaging (fMRI) is a medical imaging modality that indirectly measures neural activity by observing the local hemodynamics, or blood oxygen level dependent signal (BOLD). fMRI data offers a range of insights, and can be roughly divided into two categories:
Diffuse axonal injury after a motorcycle accident. MRI after 3 days: on T1-weighted images the injury is barely visible. On the FLAIR, DWI and T2*-weighted images a small bleed is identifiable. DAI is difficult to detect since it does not show up well on CT scans or with other macroscopic imaging techniques, though it shows up microscopically. [9]
A magnetic resonance imaging instrument (MRI scanner), or "nuclear magnetic resonance imaging" scanner as it was originally known, uses powerful magnets to polarize and excite hydrogen nuclei (i.e., single protons) of water molecules in human tissue, producing a detectable signal which is spatially encoded, resulting in images of the body. [5]