Gray matter is mildly anisotropic in normal and early ischemic states. However, early white matter ischemia is associated with not only changes in trace ADC values but also significant changes in the anisotropy, or shape, of the water self-diffusion tensor.

Background and Purpose— Pretreatment infarct volume appears to predict clinical outcome after intra-arterial therapy. To confirm the importance of infarct size in patients undergoing intra-arterial therapy, we sought to characterize the relationship between final infarct volume (FIV) and long-term functional outcome in a prospective cohort of endovascularly treated patients. Methods— From our prospective intra-arterial therapy database, we identified 107 patients with acute ischemic stroke with anterior circulation proximal artery occlusions who underwent final infarct imaging and had 3-month modified Rankin Scale scores. Clinical, imaging, treatment, and outcome data were analyzed. Results— Mean age was 66.6 years. Median admission National Institutes of Health Stroke Scale score was 17. Reperfusion (Thrombolysis In Cerebral Infarction 2A–3) was achieved in 78 (72.9%) patients. Twenty-seven (25.2%) patients achieved a 3-month good outcome (modified Rankin Scale 0–2), and 30 (28.0%) died. Median FIV was 71.4 cm 3 . FIV independently correlated with functional outcome across the entire modified Rankin Scale. In receiver operating characteristic analysis, it was the best discriminator of both good outcome (area under the curve=0.857) and mortality (area under the curve=0.772). A FIV of approximately 50 cm 3 demonstrated the greatest accuracy for distinguishing good versus poor outcome, and a FIV of approximately 90 cm 3 was highly specific for a poor outcome. The interaction term between FIV and age was the only independent predictor of good outcome ( P <0.0001). The impact of FIV was accentuated in patients <80 years. Conclusions— Among patients with anterior circulation acute ischemic stroke who undergo intra-arterial therapy, final infarct volume is a critical determinant of 3-month functional outcome and appears suitable as a surrogate biomarker in proof-of-concept intra-arterial therapy trials.

Background and Purpose-We sought to characterize the evolution of acute ischemic stroke by MRI and its relationship to patients' neurological outcome. Methods-Fourteen patients with acute ischemic stroke underwent MRI within 13 hours of symptom onset (mean, 7.4Ϯ3 hours) and underwent repeated imaging and concurrent neurological examination at 8, 24, 36, and 48 hours and 7 days and Ͼ42 days after first imaging. Results-Diffusion-weighted imaging (DWI) lesion volumes increased between the first and second scans in 10 of 14 patients; scans with maximum DWI lesion volume occurred at a mean of 70.

Objective: Diffusion-weighted imaging (DWI) conveys temporal as well as anatomic information about brain infarction, and is therefore well suited to identify ischemic injury that has occurred simultaneously, or closely linked in time, with a transient ischemic attack (TIA). We aimed to determine the proportion and clinical characteristics of patients with TIA who harbor infarction(s) on DWI. Methods: Using T₂-weighted imaging (T₂-WI), fast fluid attenuated inversion recovery (FLAIR), and DWI, we studied 57 consecutive patients presenting with acute focal neurologic symptoms lasting less than 24 h. Results: A hyperintense DWI lesion was identified in a vascular territory appropriate to the symptoms in 27 patients (47%). Lesions judged to be clinically appropriate on T₂-WI and FLAIR overlapped with a DWI lesion in 41 and 48% of patients, respectively. Independent predictors of infarction on DWI were previous nonstereotypic TIAs, presentation with motor symptoms, and identified stroke mechanism. Conclusion: DWI establishes that recent infarction occurs in almost half of patients with the clinical syndrome of TIA and this subgroup is more likely to harbor an underlying cardiac or cerebrovascular abnormality.

BACKGROUND AND PURPOSE:Multidetector CT angiography (MDCTA) is emerging as the favored initial diagnostic examination in the evaluation of patients presenting with spontaneous intraparenchymal hemorrhage (IPH). This study aims to evaluate the diagnostic accuracy and yield of MDCTA for the detection of vascular etiologies in adult patients presenting to the emergency department with IPH.