Diffusion-Weighted Magnetic Resonance Imaging May Underestimate Acute Ischemic Lesions Cautions on Neglecting a Computed Tomography-Diffusion-Weighted Imaging Discrepancy

Background ischemic lesions in acute ischemic stroke patients, which is termed reversed discrepancy (RD), but its clinical significance remains unclear. The incidence and factors associated with RD in acute ischemic stroke patients within 3 hours of onset were examined. Methods-A total of 164 consecutive patients with acute anterior circulation ischemic stroke was enrolled. All patients underwent both magnetic resonance imaging and CT within 3 hours of onset and before treatment. Their early ischemic changes were evaluated with the Alberta Stroke Program Early CT Score. RD was defined as present when the early ischemic change detected on CT was not seen on diffusion-weighted imaging. Results-RD was found in 40 patients (24%). RD group patients were older (78.7 +/- 9.6 versus 74.1 +/- 12.1 years; P=0.03) and had a higher admission National Institutes of Health Stroke Scale score (median, 22 versus 11; P<0.01), higher rates of atrial fibrillation (75% versus 42%; P<0.01), a higher rate of internal carotid artery/middle cerebral artery proximal occlusion (55% versus 28%; P<0.01), and lower CT-Alberta Stroke Program Early CT Score (median 5 versus 10; P<0.01) and diffusion-weighted imaging-Alberta Stroke Program Early CT Score (7 versus 9; P<0.01) than patients in the non-RD group. Multivariate logistic regression analysis demonstrated that atrial fibrillation was independently associated with the presence of RD (odds ratio, 2.47; 95% CI, 1.05-6.12). Conclusions-RD is observed in a quarter of acute ischemic stroke patients. RD should be taken into consideration, especially in patients with atrial fibrillation, to prevent underestimating the extent of ischemic lesions. (Stroke. 2013;44:1056-1061.)