Predictors of hemorrhagic transformation after intravenous recombinant tissue plasminogen activator: prognostic value of the initial apparent diffusion coefficient and diffusion-weighted lesion volume

Background and Purpose — Hemorrhagic transformation (HT) is a potentially dangerous complication of thrombolytic therapy. Recent studies suggest that diffusion-weighted MRI (DWI) can help to predict the risk of intracerebral hemorrhage (ICH) after thrombolysis. We sought to examine which pretreatment DWI parameters and clinical data are predictive of ICH after intravenous thrombolysis. Methods — We retrospectively reviewed our prospective stroke database for patients with ischemic stroke treated with intravenous recombinant tissue plasminogen activator (rtPA) within 3 hours from symptom onset who had DWI before treatment and MRI with T2* sequence or CT 24 to 48 hours later to assess for ICH over the past 4 years. We measured the volumes and voxel-by-voxel apparent diffusion coefficient (ADC) values of the initial DWI lesions and retrieved demographic data, risk factors, National Institutes of Health Stroke Scale (NIHSS) scores on admission, and blood tests results. We examined several variables using univariate and multivariate regression analyses to determine predictors of ICH. Results — Twenty-nine patients fulfilled our inclusion criteria; 17 patients (58%) had ICH, and of these 4 (13%) had symptomatic ICH and fatal outcome. On univariate analysis, higher systolic blood pressure, NIHSS score, serum glucose level, volume of initial DWI lesion, and absolute number of voxels with ADC value ≤550×10 −6 mm 2 /s were statistically associated with ICH, and all were subjected to multivariate analysis. However, only the absolute number of voxels, ie, volume of ischemic tissue on DWI, with ADC ≤550×10 −6 mm 2 /s emerged as an independent predictor of ICH. Conclusions — Our findings suggest that volumetric ADC analysis can be used to assess ICH risk after thrombolysis. This may be particularly helpful if rtPA is to be given outside the 3-hour window.