Background and Purpose-This study was designed to analyze whether early diffusion-weighted imaging (DWI) provides reliable quantitative information for the prediction of stroke patients at risk of malignant brain infarct. Methods-We selected 28 patients with a middle cerebral artery (MCA) infarct and proven MCA or carotid T occlusion on DWI and MRI angiography performed within 14 hours after onset (mean 6.5Ϯ3.5 hours, median 5.2 hours). Of these, 10 patients developed malignant MCA infarct, whereas 18 did not. For the 2 groups, we compared the National Institutes of Health Stroke Scale (NIHSS) score at admission, site of arterial occlusion, standardized visual analysis of DWI abnormalities, quantitative volume measurement of DWI abnormalities (volume DWI ), and apparent diffusion coefficient values. Univariate and multivariate discriminant analysis was used to determine the most accurate predictors of malignant MCA infarct. Results-Univariate analysis showed that an admission NIHSS score Ͼ20, total versus partial MCA infarct, and volume DWI Ͼ145 cm 3 were highly significant predictors of malignant infarct. The best predictor was volume DWI Ͼ145 cm 3 , which achieved 100% sensitivity and 94% specificity. Prediction was further improved by bivariate models combining volume DWI and apparent diffusion coefficient measurements, which reached 100% sensitivity and specificity in this series of patients. Conclusions-Quantitative

Background-Diffusion-weighted imaging (DWI) is the most sensitive MR sequence in acute arterial ischemic stroke buthas not yet been evaluated in venous cerebral ischemia. We describe a patient with DWI performed at the acute phase of a venous ischemic stroke. Case Description-A rapid cerebral MRI including DWI and fast fluid-attenuated inversion recovery (FLAIR) sequences was performed at the acute phase of a venous stroke confirmed by conventional angiography. DWI showed a slight decrease in apparent diffusion coefficient values 3 hours after onset (0.53Ϯ0.07ϫ10 Ϫ3 mm 2 /s) and was normal 48 hours later (0.064Ϯ0.15ϫ10Ϫ3 mm 2 /s). Fast FLAIR sequences showed large left frontoparietal hyperintensities. The lack of a clear decrease in apparent diffusion coefficient values associated with marked FLAIR abnormalities may suggest prominent or early associated vasogenic edema. Physiopathological differences between arterial and venous ischemia may explain the different type of DWI FLAIR abnormalities during the acute phase as well as the better recovery of neurological deficit in venous stroke than in arterial ischemic stroke. Conclusions-In the context of an acute stroke, the contrast between marked FLAIR and subtle DWI abnormalities on MRI may reflect the venous mechanism of cerebral ischemia.

Six patients with cerebral ischaemia who presented evolving isolated hand palsy were studied, five prospectively and one retrospectively. The motor deficit involved only the hand and the wrist in some cases. In almost all cases the motor deficit was pseudo-ulnar. None of them had a Babinski sign, all had mild sensory symptoms or signs in the affected hand. CT and MRI disclosed recent infarctions contralateral to the affected hand, in the white matter of the angular gyrus, in a vascular borderzone. Five had a tight stenosis of the internal carotid artery. The pyramidal tract was anatomically spared in three cases, even considering its parietal origin. Consistent with previous data, our study suggests that the parietal lobe is involved in the control of the motor function of the hand. We propose the existence of a new entity, characterized by an evolving non-pyramidal motor deficit in the hand following infarction of the angular gyrus of the inferior parietal lobe.

We evaluated the feasibility and use of diffusion-weighted and fluid-attenuated inversion-recovery pulse sequences performed as an emergency for patients with acute ischaemic stroke. A 5-min MRI session was designed as an emergency diagnostic procedure for patients admitted with suspected acute ischaemic stroke. We reviewed routine clinical implementation of the procedure, and its sensitivity and specificity for acute ischaemic stroke over the first 8 months. We imaged 91 patients (80 min to 48 h following the onset of stroke). Clinical deficit had resolved in less than 3 h in 15 patients, and the remaining 76 were classified as stroke (59) or stroke-like (17) after hospital discharge. Sensitivity of MRI for acute ischaemic stroke was 98%, specificity 100%. MRI provided an immediate and accurate picture of the number, site, size and age of ischaemic lesions in stroke and simplified diagnosis in stroke-like episodes. The feasibility and high diagnostic accuracy of emergency MRI in acute stroke strongly support its routine use in a stroke centre.

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