DWI-FLAIR Mismatch at MRI Versus Infarct-Penumbra Mismatch on CT Perfusion.

A 90-year-old female patient was brought to our hospital by ambulance after her husband found her somnolent and mute upon waking. Upon arrival, neurological and physical examinations showed spastic flexion of the right arm and deviation of gaze to the left. A so-called ‘wake-up stroke procedure’ was triggered and brain magnetic resonance imaging (MRI), including fluid-attenuation inversionrecovery (FLAIR) and diffusion weighted imaging (DWI) acquisitions, was immediately performed (Figure 1). Axial FLAIR images showed only leukoaraiosis (Figure 1A). DWI demonstrated high signal intensity in the territory of left middle cerebral artery (MCA) at high b-value (Figure 1B) with decreased apparent diffusion coefficient values. MRangiography was precluded by patient’s movements. Non-contrast CT (NCCT), CT-angiography (CTA), and CT-perfusion (CTP) were thereafter performed for angiographic assessment including carotid arteries, circle of Willis, and intracranial collateral circulation (Figure 2)