Predicting final infarct size using acute and subacute multiparametric MRI measurements in patients with ischemic stroke

Purpose To identify early MRI characteristics of ischemic stroke that predict final infarct size three months poststroke. Materials and Methods Multiparametric MRI (multispin echo T2-weighted [T2W] imaging, T1-weighted [T1W] imaging, and diffusion-weighted imaging [DWI]) was performed acutely (<24 hours), subacutely (three to five days), and at three months. MRI was processed using maps of apparent diffusion coefficient (ADC), T2, and a self-organizing data analysis (ISODATA) technique. Analyses began with testing for individual MRI parameter effects, followed by multivariable modeling with assessment of predictive ability (R2) on final infarct size. Results A total of 45 patients were studied, 15 of whom were treated with tissue plasminogen activator (tPA) before acute MRI. The acute DWI and DWI-ISODATA mismatch lesion size, and the interactions of ADC, T2, and T2W imaging lesion with tPA remained in the final multivariable model (R2 = 70%). A large acute DWI lesion or DWI acute DWI lesion size predicted an increased final infarct size (P < 0.01). Conclusion Acute-phase DWI and DWI-ISODATA mismatch strongly predict the final infarct size. An acute-to-subacute DWI lesion size change further increases the predictive ability of the model. J. Magn. Reson. Imaging 2005;21:495–502. © 2005 Wiley-Liss, Inc.