Diffusion-weighted imaging (DWI) is commonly used to assess irreversibly infarcted tissue but its accuracy is challenged by reports of diffusion lesion reversal (DLR). We investigated the frequency and implications for mismatch classification of DLR using imaging from the EPITHET (Echoplanar Imaging Thrombolytic Evaluation Trial) and DEFUSE (Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution) studies. In 119 patients (83 treated with IV tissue plasminogen activator), follow-up images were coregistered to acute diffusion images and the lesions manually outlined to their maximal visual extent in diffusion space. Diffusion lesion reversal was defined as voxels of acute diffusion lesion that corresponded to normal brain at follow-up (i.e., final infarct, leukoaraiosis, and cerebrospinal fluid (CSF) voxels were excluded from consideration). The appearance of DLR was visually checked for artifacts, the volume calculated, and the impact of adjusting baseline diffusion lesion volume for DLR volume on perfusion-diffusion mismatch analyzed. Median DLR volume reduced from 4.4 to 1.5 mL after excluding CSF/leukoaraiosis. Visual inspection verified 8/119 (6.7%) with true DLR, median volume 2.33 mL. Subtracting DLR from acute diffusion volume altered perfusion-diffusion mismatch (T max > 6 seconds, ratio > 1.2) in 3/119 (2.5%) patients. Diffusion lesion reversal between baseline and 3 to 6 hours DWI was also uncommon (7/65, 11%) and often transient. Clinically relevant DLR is uncommon and rarely alters perfusion-diffusion mismatch. The acute diffusion lesion is generally a reliable signature of the infarct core.

Objectives: Antiplatelet therapy (APT) promotes bleeding; therefore, APT might worsen outcome in patients with intracerebral hemorrhage (ICH). We performed a systematic review and metaanalysis to address the hypothesis that pre-ICH APT use is associated with mortality and poor functional outcome following ICH. Methods:The Medline and Embase databases were searched in February 2008 using relevant key words, limited to human studies in the English language. Cohort studies of consecutive patients with ICH reporting mortality or functional outcome according to pre-ICH APT use were identified. Of 2,873 studies screened, 10 were judged to meet inclusion criteria by consensus of 2 authors. Additionally, we solicited unpublished data from all authors of cohort studies with Ͼ100 patients published within the last 10 years, and received data from 15 more studies. Univariate and multivariable-adjusted odds ratios (ORs) for mortality and poor functional outcome were abstracted as available and pooled using a random effects model. Results:We obtained mortality data from 25 cohorts (15 unpublished) and functional outcome data from 21 cohorts (14 unpublished). Pre-ICH APT users had increased mortality in both univariate (OR 1.41, 95% confidence interval [CI] 1.21 to 1.64) and multivariable-adjusted (OR 1.27, 95% CI 1.10 to 1.47) pooled analyses. By contrast, the pooled OR for poor functional outcome was no longer significant when using multivariable-adjusted estimates (univariate OR 1.29, 95% CI 1.09 to 1.53; multivariable-adjusted OR 1.10, 95% CI 0.93 to 1.29). Conclusions:In cohort studies, APT use at the time of ICH compared to no APT use was independently associated with increased mortality but not with poor functional outcome. Neurology GLOSSARYAPT ϭ antiplatelet therapy; CI ϭ confidence interval; GOS ϭ Glasgow Outcome Scale; ICH ϭ intracerebral hemorrhage; mRS ϭ modified Rankin Scale; OR ϭ odds ratio.Aspirin or other antiplatelet therapy (APT) could worsen outcome from intracerebral hemorrhage (ICH) by promoting bleeding. Published observational studies of outcomes in pre-ICH APT users have yielded conflicting results, however. Some suggest an increased risk of poor outcome 1-3 while others suggest no increased risk. 4,5 If prior APT worsens outcome, then restoration of normal platelet function could be a therapeutic target.We hypothesized that pre-ICH APT use would be associated with increased mortality and functional impairment following ICH, and tested this hypothesis by performing a systematic review of the literature. To reduce the likelihood of publication bias, we additionally requested information from established cohort studies that had not previously published on the association between pre-ICH APT and clinical outcomes.METHODS Search strategy, selection criteria, and data abstraction. Using the Meta-analysis of Observational Studies in Epidemiology (MOOSE) criteria as a guide, 6 we searched for studies describing mortality or functional outcome of consecutive adults with spontaneous ICH by APT use, ex...

No abstract

True DWI lesion reversal is uncommon in ischemic stroke patients. The volume of apparent lesion reversal is small and would rarely affect treatment decisions based on perfusion-diffusion mismatch.