Fluid attenuated inversion recovery imaging

Figure 18.1. MRI signal abnormalities in the brain and spinal cord in a 55-year-old woman with multiple sclerosis. (A) FLAIR (Fluid attenuated inversion recovery) image of axial brain image at the level of the lateral ventricles. Arrows point to hyperintense periventricular lesions demonstrating a characteristics MS demyelination pattern (B) T2W image of sagittal view of the spinal cord of the same individual, demonstrating focal bright signal (arrow) representing demyelination in the cervical spinal cord.

Maeda, M., et al., Time course of arterial hyperintensity with fast fluid-attenuated inversion-recovery imaging in acute and subacute middle cerebral arterial infarction. J Magn Reson Imaging, 2001. 13(6) p. 987-90. 

Another method to optimize image contrast includes the addition of an inversion recovery pulse before the typical SE sequence to suppress signal from cerebrospinal fluid (CSF). This yields so-called fluid-attenuated inversion recovery (FLAIR)-or CSF-suppressed DWI images or ADC maps. With this approach, the partial-volume effect of cerebrospinal fluid can be substantially reduced, which is particularly relevant in cortical regions due to the frequent CSF contribution to individual voxels (Latour and Warach 2002). The technique may enhance lesion conspicuity in the vicinity of CSF and has been shown to be of value in research studies utilizing pixel-wise analyses to predict tissue fate. The technique is not yet implemented in many centers, although this may change in the near future. 

Fig. 9.2. Fluid-attenuated inversion recovery (FLAIR, upper row) and T2-weighted (lower row) magnetic resonance images demonstrating early small focal lesions of leukoaraiosis...

Anzai Y, Ishikawa M, Shaw DW et al (2004) Paramagnetic effect of supplemental oxygen on CSF hyperintensity on fluid-attenuated inversion recovery MR images. AJNR Am J Neuroradiol 25 274-279... 

Woodcock RJ Jr, Short J, Do HM et al (2001) Imaging of acute subarachnoid hemorrhage with a fluid-attenuated inversion recovery sequence in an animal model comparison with non-contrast-enhanced CT. AJNR Am J Neuroradiol 22 1698-1703... 

T cell activation and can interfere with cytoskeletal components that prevent interleukin-2 sjmthesis and release. Cytotoxic edema caused by acute cerebral ischemia is associated with reduced diffusion, reflecting the failure of membrane sodium pumps. Altered electrolyte or fluid balance can precede the onset of encephalopathy. This can be shown by fluid-attenuated inversion recovery and diffusion-weighted MRI images (36). 

Singer MB, Atlas SW, Drayer BP (1998) Subarachnoid space disease diagnosis with fluid-attenuated inversion-recovery MR imaging and comparison with gadolinium-enhanced spin-echo MR imaging- blinded reader study. Radiology 208 417-422. 

Ricci, P.E., et al., A comparison of fast spin-echo, fluid-attenuated inversion-recovery, and diffusion-weighted MR imaging in the first 10 days after cerebral infarction. AJNR Am J Neuroradiol, 1999. 20(8) p. 1535-42. 

Fig. 9.5 Magnetic resonance imaging of the brain T2-weighted images using FLAIR (fluid attenuated inversion recovery) and FSE (fast spin echo) reveal enhanced signal intensity representing white matter abnormalities...

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