Diffusion-Weighted Imaging and National Institutes of Health Stroke Scale in the Acute Phase of Posterior-Circulation Stroke

Open Access
Publisher Website
Google Scholar
Abstract
MOST MEDICAL centers perform a noncontrast computed tomographic (CT) scan to examine patients with acute strokes.1,2 There are controversies regarding the capability of CT in the evaluation of hyperacute stroke in all vascular territories.3-5 Occlusive disease of the posterior circulation represents a heterogeneous group of strokes markedly different from strokes in other territories in cause, clinical presentation, and prognosis.6 Computed tomography provides suboptimal visualization of posterior fossa structures and infarcts.7,8 The anatomic definition of traditional magnetic resonance (MR) imaging sequences (ie, T2-weighted imaging [T2WI]) has been used for clinicoradiologic correlation studies of posterior-circulation ischemia in the subacute phase.9 Magnetic resonance imaging by diffusion-weighted imaging (DWI) is able to detect changes in ischemic brain tissue as early as 2.5 minutes after arterial occlusion in experimental animals10,11 and is highly sensitive in the hyperacute examination of patients with stroke.3,4 The DWI allows calculation of the apparent diffusion coefficient of water.12 Decreased apparent diffusion coefficient of water correlates with (1) failure of the adenosine triphosphate–dependent sodium/potassium pumps, (2) increase in glutamate tissue concentration, and (3) size of infarcted tissue on histologic examination.10,13-15