Apparent diffusion coefficient threshold for delineation of ischemic core

作者：Purushotham Archana^*; Campbell Bruce C V; Straka Matus; Mlynash Michael; Olivot Jean Marc; Bammer Roland; Kemp Stephanie M; Albers Gregory W; Lan**erg Maarten G

来源：International Journal of Stroke, 2015, 10(3): 348-353.

DOI：10.1111/ijs.12068

• apparent diffusion coefficient
• diffusion MRI
• diffusion-perfusion imaging
• ischemic core
• ischemic stroke
• neuroimaging of acute stroke

BackgroundMRI-based selection of patients for acute stroke interventions requires rapid accurate estimation of the infarct core on diffusion-weighted MRI. Typically used manual methods to delineate restricted diffusion lesions are subjective and time consuming. These limitations would be overcome by a fully automated method that can rapidly and objectively delineate the ischemic core. An automated method would require predefined criteria to identify the ischemic core.
AimThe aim of this study is to determine apparent diffusion coefficient-based criteria that can be implemented in a fully automated software solution for identification of the ischemic core.
MethodsImaging data from patients enrolled in the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution (DEFUSE) study who had early revascularization following intravenous thrombolysis were included. The patients' baseline restricted diffusion and 30-day T-2-weighted fluid-attenuated inversion recovery lesions were manually delineated after coregistration. Parts of the restricted diffusion lesion that corresponded with 30-day infarct were considered ischemic core, whereas parts that corresponded with normal brain parenchyma at 30 days were considered noncore. The optimal apparent diffusion coefficient threshold to discriminate core from noncore voxels was determined by voxel-based receiver operating characteristics analysis using the Youden index.
Results51045 diffusion positive voxels from 14 patients who met eligibility criteria were analyzed. The mean DWI lesion volume was 24 (23) ml. Of this, 18 (+/- 22) ml was ischemic core and 3 (+/- 5) ml was noncore. The remainder corresponded to preexisting gliosis, cerebrospinal fluid, or was lost to postinfarct atrophy. The apparent diffusion coefficient of core was lower than that of noncore voxels (P<00001). The optimal threshold for identification of ischemic core was an apparent diffusion coefficient 620x10(-6)mm(2)/s (sensitivity 69% and specificity 78%).
ConclusionsOur data suggest that the ischemic core can be identified with an absolute apparent diffusion coefficient threshold. This threshold can be implemented in image analysis software for fully automated segmentation of the ischemic core.

• 出版日期2015-4