CT Reconstruction Levels Affect Automated and Reader-Based ASPECTS Ratings in Acute Ischemic Stroke

BACKGROUND AND PURPOSE We investigated whether automated and reader-based ASPECTS in acute stroke patients are affected by different CT image reconstruction algorithms. METHODS ASPECTS were assessed by commercial software and four independent blinded readers (two residents and two consultants) from different CT reconstructions (filtered back projection and two different iterative reconstruction [IR] levels) in 43 acute stroke patients with proximal middle cerebral artery occlusion. Ground truth was provided by an expert with unrestricted data access. RESULTS The residents showed significant variations between IR levels and had a significantly lower internal consistency across different reconstructions compared to the software, which performed similarly to the consultants. The consultant as well as the software also showed different deviations from ground truth with different IR levels, which were least at IR strength level 2. CONCLUSIONS CT image postprocessing affects either automated or human ASPECTS in acute stroke patients. This effect was most pronounced in the less experienced readers, while the software had the most robust performance.