🤖 AI Summary
This study addresses the challenge of assessing cerebrovascular reserve in Moyamoya disease patients with acetazolamide contraindications by proposing CAE3D, a three-dimensional conditional autoencoder that non-invasively synthesizes post-challenge cerebral blood flow maps from baseline ASL images. This work represents the first validation of retrospectively generating stress perfusion data from baseline MRI using a deterministic architecture integrating perfusion imaging with deep learning. Experimental results demonstrate superior performance over various 3D generative and foundation models, achieving a mean absolute error of 0.066, a structural similarity index of 0.80, and near-zero whole-brain bias. Consequently, this method establishes a novel paradigm for precise hemodynamic assessment in contraindicated patients, effectively bridging advanced deep learning techniques with clinical neuroimaging requirements to overcome diagnostic limitations associated with pharmacological vasodilators.
📝 Abstract
For patients with Moyamoya disease, impaired cerebrovascular reserve (CVR) is an important hemodynamic criterion for recommending extracranial-to-intracranial bypass surgery. Standard CVR assessment in this cohort uses paired arterial spin labeling (ASL) perfusion MRI acquired before and after acetazolamide (ACZ). When ACZ is contraindicated or avoided, the post-ACZ cerebral blood flow (CBF) map needed for hemodynamic assessment is unavailable. We propose CAE3D, a deterministic 3D conditional autoencoder that synthesizes post-ACZ CBF maps directly from pre-ACZ ASL input. We evaluated CAE3D against ten comparators, including deterministic and diffusion-style 3D baselines, a 2D contextual baseline, and frozen-encoder foundation-model adapters. CAE3D achieved the lowest held-out MAE (0.066), with SSIM 0.80 and PSNR 24.0 dB, and near-zero full-brain mean bias. Its MAE advantage was statistically significant over seven of eight trained-from-scratch baselines, excluding the 2D CAE_2D comparator; its SSIM and PSNR advantages were significant over all eight. Regional delta-CBF predictions compressed the dynamic range in high-response territories. These results establish the retrospective feasibility of post-ACZ CBF synthesis in patients who completed the standard two-scan protocol. Extension to ACZ-contraindicated patients, who were not represented in this cohort, requires external and prospective validation.