Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Radiol. Mar 28, 2012; 4(3): 63-74
Published online Mar 28, 2012. doi: 10.4329/wjr.v4.i3.63
Magnetic resonance diffusion-perfusion mismatch in acute ischemic stroke: An update
Feng Chen, Yi-Cheng Ni
Feng Chen, Yi-Cheng Ni, Department of Radiology, Catholic University of Leuven, Campus Gasthuisberg, Herestraat 49, 3000 Leuven, Belgium
Feng Chen, Department of Radiology, Zhongda Hospital, Southeast University, Nanjing 210009, Jiangsu Province, China
Author contributions: Chen F contributed to the concepts, study design, literature research, data acquisition, data analysis and interpretation, manuscript drafting and revision, and final approval of the version to be published; Ni YC contributed to the literature analysis and interpretation, manuscript drafting and revision, and final approval of the version to be published.
Correspondence to: Feng Chen, MD, PhD, Department of Radiology, Gasthuisberg, University of Leuven, Herestraat 49, Box 7003, 3000 Leuven, Belgium.
Telephone: +32-16-330165 Fax: +32-16-343765
Received: September 6, 2011
Revised: February 22, 2012
Accepted: March 1, 2012
Published online: March 28, 2012

The concept of magnetic resonance perfusion-diffusion mismatch (PDM) provides a practical and approximate measure of the tissue at risk and has been increasingly applied for the evaluation of hyperacute and acute stroke in animals and patients. Recent studies demonstrated that PDM does not optimally define the ischemic penumbra; because early abnormality on diffusion-weighted imaging overestimates the infarct core by including part of the penumbra, and the abnormality on perfusion weighted imaging overestimates the penumbra by including regions of benign oligemia. To overcome these limitations, many efforts have been made to optimize conventional PDM. Various alternatives beyond the PDM concept are under investigation in order to better define the penumbra. The PDM theory has been applied in ischemic stroke for at least three purposes: to be used as a practical selection tool for stroke treatment; to test the hypothesis that patients with PDM pattern will benefit from treatment, while those without mismatch pattern will not; to be a surrogate measure for stroke outcome. The main patterns of PDM and its relation with clinical outcomes were also briefly reviewed. The conclusion was that patients with PDM documented more reperfusion, reduced infarct growth and better clinical outcomes compared to patients without PDM, but it was not yet clear that thrombolytic therapy is beneficial when patients were selected on PDM. Studies based on a larger cohort are currently under investigation to further validate the PDM hypothesis.

Keywords: Diffusion, Ischemic, Magnetic resonance imaging, Mismatch, Penumbra, Perfusion, Stroke