Quantifying Infarct Growth and Secondary Injury Volumes
Comparing Multimodal Image Registration Measures
Background and Purpose—Lesion expansion in the week after acute stroke involves both infarct growth (IG) and anatomic distortion (AD) because of edema and hemorrhage. Enabling separate quantification would allow clinical trials targeting these distinct pathological processes. We developed an objective and automated approach to quantify these processes at 24 hours and 1 week.
Methods—Patients with acute ischemic stroke were scanned at presentation, 24 hours, and 1 week in a magnetic resonance imaging (MRI) cohort study. IG and AD were calculated from follow-up lesion masks after linear and nonlinear registration to a presenting MRI scan. Performance of IG and AD was compared with edema quantified using cerebrospinal fluid displacement. The use of alternative reference images to define AD, including template MRI, mirrored MRI, and presenting computed tomographic scan, was explored.
Results—Thirty-seven patients with nonlacunar stroke were included. AD was responsible for 20% and 36% of lesion expansion at 24 hours (n=30) and 1 week (n=28). Registration-defined IG and AD compared favorably with edema quantified using cerebrospinal fluid displacement, particularly at smaller infarct volumes. Presenting computed tomographic imaging was the preferred alternative reference image to presenting MRI for measuring AD.
Conclusions—The contributions of IG and AD to lesion expansion can be measured separately over time through the use of image registration. This approach can be used to combine imaging outcome data from computed tomography and MRI.
- Received January 15, 2018.
- Revision received May 1, 2018.
- Accepted May 14, 2018.
- © 2018 The Authors.
Stroke is published on behalf of the American Heart Association, Inc., by Wolters Kluwer Health, Inc. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution, and reproduction in any medium, provided that the original work is properly cited.