Identifying lesion growth with MR imaging in acute ischemic stroke

Purpose To determine whether different MR diffusion‐ and perfusion‐weighted imaging (DWI and PWI) parameters are important in distinguishing lesion growth from the acute lesion and from oligemia. Materials and Methods MR DWI and PWI were acquired from thirteen patients. We defined three regions: (i) LESION ‐ intersection of acute and final lesions, (ii) GROWTH ‐ portion of final lesion not part of acute lesion, and (iii) OLIGEMIA ‐ region of perfusion abnormality not part of either the acute or final lesions. We used logistic regression modeling to distinguish GROWTH from LESION and from OLIGEMIA on a voxel‐wise basis using DWI‐ and PWI‐based parameters. Final models were selected based on the Wald statistic and validated by cross‐validation using the mean (± standard deviation) area under the curve (AUC) from receiver operating characteristic analysis. Results The final model for differentiating GROWTH from LESION included DWI, the apparent diffusion coefficient (ADC), cerebral blood flow (CBF) and tissue type (AUC = 0.939 ± 0.028). The final model for differentiating GROWTH from OLIGEMIA included DWI, ADC, CBF, and time‐to‐peak (AUC = 0.793 ± 0.106). Conclusion Different MR parameters are important in differentiating lesion growth from acute lesion and from oligemia in acute ischemic stroke. J. Magn. Reson. Imaging 2008;28:837–846. © 2008 Wiley‐Liss, Inc.