MRI for prediction of hemorrhagic transformation in acute ischemic stroke: a systematic review and meta-analysis

Background Hemorrhagic transformation increases mortality and morbidity in patients with acute ischemic stroke. Purpose The purpose of this study is to evaluate the diagnostic performance of magnetic resonance imaging (MRI) for prediction of hemorrhagic transformation in acute ischemic stroke. Material and Methods A systematic literature search of MEDLINE and EMBASE was performed up to 27 July 2018, including the search terms "acute ischemic stroke," "hemorrhagic transformation," and "MRI." Studies evaluating the diagnostic performance of MRI for prediction of hemorrhagic transformation in acute ischemic stroke were included. Diagnostic meta-analysis was conducted with a bivariate random-effects model to calculate the pooled sensitivity and specificity. Subgroup analysis was performed including studies using advanced MRI techniques including perfusion-weighted imaging, diffusion-weighted imaging, and susceptibility-weighted imaging. Results Nine original articles with 665 patients were included. Hemorrhagic transformation is associated with high permeability, hypoperfusion, low apparent diffusion coefficient (ADC), and FLAIR hyperintensity. The pooled sensitivity was 82% (95% confidence interval [CI] 61-93) and the pooled specificity was 79% (95% CI 71-85). The area under the hierarchical summary receiver operating characteristic curve was 0.85 (95% CI 0.82-0.88). Although study heterogeneity was present in both sensitivity (I-2=67.96%) and specificity (I-2=78.93%), a threshold effect was confirmed. Studies using advanced MRI showed sensitivity of 92% (95% CI 70-98) and specificity of 78% (95% CI 65-87) to conventional MRI. Conclusion MRI may show moderate diagnostic performance for predicting hemorrhage in acute ischemic stroke although the clinical significance of this hemorrhage is somewhat uncertain.