Can Diffusion-Weighted Imaging–Fluid-Attenuated Inversion Recovery Mismatch (Positive Diffusion-Weighted Imaging/Negative Fluid-Attenuated Inversion Recovery) at 3 Tesla Identify Patients With Stroke at <4.5 Hours?

Abstract

Background and Purpose-At 1.5 T, diffusion-weighted imaging-fluid-attenuated inversion recovery (DWI-FLAIR) mismatch helps identify strokes within 4.5 hours of onset. However, at 3T, studies have found divergent results. The goal of this study was to determine whether DWI-FLAIR mismatch at 3T would also be helpful for identifying patients within 4.5 hours of symptom onset. Methods-All patients presenting with an ischemic stroke in the middle cerebral artery territory and explored with 3T MRI within 12 hours between November 2007 and April 2012 were included in this retrospective study. Two readers analyzed the DWI and FLAIR images. Logistic regression was performed to determine independent predictors of FLAIR visibility. Also, the predictive values of a mismatch for identifying patients with stroke onset ≤4.5 hours were estimated. Results-The study included 194 patients. The only predictive factor of FLAIR visibility was delayed MRI acquisition. The DWI-FLAIR mismatch was able to identify patients within 4.5 hours of stroke onset with relatively low sensitivity (0.55; 95% confidence interval, 0.48-0.63), low specificity (0.60; 95% confidence interval, 0.42-0.77), high positive predictive value (0.88; 95% confidence interval, 0.82-0.94), and very low negative predictive value (0.19; 95% confidence interval, 0.11-0.28). In addition, 44.5% of patients had a positive FLAIR sequence within 4.5 hours. Conclusions-This study improves our understanding of DWI-FLAIR mismatch as an imaging biomarker for wake-up management of patients with stroke. At 3T, the presence of a DWI-FLAIR mismatch was able to identify stroke onset of <4.5 hours. from symptom onset within the first 4.5 hours because of low sensitivity. 10The goal of the present study was to determine whether the DWI-FLAIR mismatch at 3T might be a good marker for identifying those patients who are within 4.5 hours of ischemic stroke symptom onset. Materials and Methods PatientsPatients with ischemic strokes in the middle cerebral artery territory who underwent 3T MRI at our institution during the first 12 hours of symptom onset were retrospectively studied during the period from November 2007 to April 2012. They were identified from the registry of the stroke unit. Patients were included if they had a precise time of stroke symptom onset and if they had undergone DWI and FLAIR imaging. The study had the approval of the local institutional review board. According to the study design, written informed consent was waived.Initially, 234 patients were included in the study. Patients with FLAIR images showing major artifacts (n=20; 8.9%) were excluded, as were those with multiple lesions of different ages (n=20; 8.9%), because of the difficulty of attributing lesions to the stroke symptoms used to date it.11 Ultimately, data from 194 patients were analyzed. For each patient, demographic data (sex, age), National Institutes of Health Stroke Scale (NIHSS) score at admission, and stroke symptom onset time to determine the stroke onset-to-MRI delay were collected. MRI Proto...

Does b1000–b0 Mismatch Challenge Diffusion-Weighted Imaging–Fluid Attenuated Inversion Recovery Mismatch in Stroke?

“…In addition, our examinations were performed with both 1.5-T and 3-T MRI scanners, and field strength can affect lesion visibility on both DWI and FLAIR images. 7 Nevertheless, the vast majority of patients underwent MRI at 1.5 T, and after exclusion of 3.0-T examinations, measures of accuracy remained similar. Consequently, this method seems reliable at least for 1.5-T scans.…”

“…2 Diffusionweighted imaging (DWI)/fluid-attenuated inversion recovery (FLAIR) mismatch has been proposed for magnetic resonance imaging (MRI) estimation of lesion age in acute stroke 3 but still presents some drawbacks. [4][5][6][7][8] To circumvent the subjectivity of the visual rating of images using this method, different approaches have been proposed with conflicting results, 4,6,[8][9][10][11][12] and further studies are needed to verify their utility.…”

Parenchymal FLAIR hyperintensity before thrombolysis is a prognostic factor of ischemic stroke outcome at 3 Tesla

“…Moreover, in a previous study, it was demonstrated that a negative parenchymal FLAIR can determine lesion age of < 4.5 hours with a high PPV and low NPV. This study shows that a positive parenchymal FLAIR can be used to predict poor outcome at 3 months with high PPV and low NPV which means that FLAIR hyperintensity also have a prognostic value [1].…”

“…Parenchymal FLAIR signal has proved to be helpful to determine if ischemic stroke is less than 4.5 hours or not, with potential usefulness in evaluating wake up stroke patients [1][2][3]. Indeed, International guidelines dissuade thrombolytic treatment of stroke with unknown onset time [4].…”

Patient candidat à la thrombolyse : l’IRM est indispensable

“…Cependant, la sensibilité et la spécificité pour détecter un AIC de moins de 4,5 h ne sont pas parfaites (respectivement 55 % et 60 % à 3T [26]). La présence d'un mismatch diffusion-FLAIR est actuellement utilisé comme critère d'inclusion pour un essai thérapeutique sur la thrombolyse intra-veineuse pour des AVC du réveil, dont l'horaire de début est, par définition, inconnu [27].…”