What is the role of Fluid-Attenuated Inversion Recovery (FLAIR) MRI in the evaluation of ischemic stroke and its differentiation from other pathologies?

FLAIR MRI suppresses the signal from free water in cerebrospinal fluid (CSF), enhancing the visibility of T2-weighted changes in brain parenchyma. This makes it particularly useful for detecting early ischemic changes, small cortical lesions, and acute subarachnoid hemorrhage. Key diagnostic features include hyperintense signals in affected areas, while pitfalls include potential confusion with chronic microvascular changes or leukoaraiosis. FLAIR is less sensitive in the hyperacute phase of ischemia, where diffusion-weighted imaging (DWI) is preferred.