Apparent Diffusion Coefficient Threshold for Delineation of Ischemic Core

Abstract

Background MRI-based selection of patients for acute stroke interventions requires rapid accurate estimation of the infarct core on diffusion-weighted MRI (DWI). Typically used manual methods to delineate DWI 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 pre-defined criteria to identify the ischemic core. Aim To determine Apparent Diffusion Coefficient (ADC) based criteria that can be implemented in a fully automated software solution for identification of the ischemic core. Methods Imaging data from patients enrolled in the DEFUSE study who had early revascularization following tPA treatment, was included. The patients’ baseline DWI and 30-day FLAIR lesions were manually delineated after co-registration. Parts of the DWI lesion that corresponded with 30-day infarct were considered ischemic core, whereas parts that corresponded with normal brain parenchyma at 30 days were considered non-core. The optimal ADC threshold to discriminate core from non-core voxels was determined by voxel-based ROC analysis using the Youden index. Results 51045 DWI 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 non-core. The remainder corresponded to pre-existing gliosis, CSF, or was lost to post-infarct atrophy. The ADC of core was lower than that of non-core voxels (p<0.0001). The optimal threshold for identification of ischemic core was an ADC ≤620 ×10−6 mm2/s (sensitivity 69% and specificity 78%). Conclusions Our data suggests the ischemic core can be identified with an absolute ADC threshold. This threshold can be implemented in image analysis software for fully automated segmentation of the ischemic core.

Does Diffusion Lesion Volume Above 70 mL Preclude Favorable Outcome Despite Post-Thrombolysis Recanalization?

“…To date, the optimal ADC cut point to delineate the true core remains debated, given the overlap in ADC values between core and noncore voxels. 34 The use of a definite ADC/DWI threshold, implemented in some automated softwares, may yield different results regarding DWI lesion reversal and prognostic value of the 70 mL cut point. However, recanalization has been shown to be beneficial in patients with large DWI lesions segmented with such an automated software.…”

Ipsilateral Prominent Thalamostriate Vein on Susceptibility-Weighted Imaging Predicts Poor Outcome after Intravenous Thrombolysis in Acute Ischemic Stroke

“…11 For patients with CT follow-up, the area of hypoattenuation was manually outlined. Volumetric analysis was performed by using the commercial software MIStar (Apollo Medical Imaging Technology, Melbourne, Australia).…”

Association between the Perfusion/Diffusion and Diffusion/FLAIR Mismatch: Data from the AXIS2 Trial

“…Ischemic lesions here were defined as voxels with a value of below 600.10 − 6 mm 2 /s. 12,13 The DWI maps were used as a mask for defining brain tissue voxels. From the resulting set of voxels, only those clusters which were likely to be part of the ischemic lesion based on visual assessment were selected.…”