Fluid Attenuated Inversion Recovery for Detection of Subarachnoid Diseases
Fluid attenuated inversion recovery (FLAIR) is a pulse sequence used in magnetic resonance imaging and is considered to be the most sensitive MR imaging technique. This imaging technique was invented by Dr. Graeme Bydder and can be used with three dimensional imaging (3D FLAIR) or two dimensional imaging (2D FLAIR).
According to investigators, fluid attenuated inversion recovery (FLAIR) imaging is considered to be the most effective imaging technique for detection of subarachnoid disease. FLAIR MR imaging has the ability to detect subarachnoid hemorrhage (SAH), meningitis, chemical irritation of the meninges, and subarachnoid seeding of neoplasm.
Fluid attenuated inversion recovery (FLAIR) has also been compared with other imaging techniques. It is considered to be more sensitive than computed tomography (CT) for detection of subarachnoid diseases such as chemical meningitis, inflammatory meningitis, and neoplastic infiltration of the subarachnoid space. FLAIR images provide good visualization of the subarachnoid spaces within the cerebral fissures.
FLAIR is a special inversion recovery sequence with long TI (longitudinal relaxation time) to remove the effects of fluid from the images. The TI time of the FLAIR pulse sequence is adjusted to the relaxation time of the component that should be suppressed. For fluid suppression, the log TI is set to zero crossing point of fluid, resulting in the signal being erased. This is considered to be an important technique to assess lesions in the patients with brain parenchymal and meningeal lesions and also for differentiation of brain and spine lesions.
MRI Fast Fluid Attenuated Inversion Recovery (FLAIR) is an effective imaging technique for a wide range of central nervous system diseases. The images present excellent lesion conspicuity in several disease processes.