Biomarkers

Enlarged perivascular spaces (PVS) are imaging biomarkers of cerebral small vessel disease (CSVD) associated with age, hypertension, and neurodegenerative conditions. Despite their clinical relevance, accurate quantification of PVS on T1-weighted magnetic resonance imaging (MRI) remains challenging due to both variability across imaging protocols, and their small size and limited contrast. Automated methods such as convolutional neural networks (CNNs) offer a scalable solution, but existing tools are limited in performance and generalizability.

This study introduces segcsvd_PVS, a CNN-based tool designed for automated PVS segmentation on T1-weighted images, based on a hierarchical framework incorporating anatomical information and robust training strategies. It was trained on semi-automated RORPO-based ground truth data and validated using both manual and semi-automated segmentations. A large and comprehensive cohort (n = 1351) spanning multiple datasets characterized by diverse imaging protocols, patient populations, and anatomical characteristics was used for training and evaluation. Performance metrics, robustness to variations in image quality, and age-related associations with PVS burden were rigorously evaluated against established RORPO-based methods.

Segcsvd_PVS achieved high sensitivity for basal ganglia PVS (SNS = 0.81 ± 0.13) and identified significantly larger volumes (86.1 ± 67.1 mm³) compared to human tracers (47.2 ± 26.5 mm³, 48.6 ± 28.4 mm³. Our tool demonstrated strong age-related correlations with PVS volumes across three diverse datasets (TEST: r = 0.41, CI = [0.03, 0.68]; ADNI: r = 0.38, CI = [0.30, 0.46]; CAHHM: r = 0.41, CI = [0.35, 0.46]). Although similar but weaker trends were observed for non-basal ganglia PVS, segcsvd_PVS demonstrated superior robustness to variations in contrast and noise across both regions, with minimal changes in age-related correlations (∆r ≤ 0.08) compared to the RORPO-based methods (∆r ≤ 0.39).

Segcsvd_PVS is a reliable tool for PVS segmentation, particularly in basal ganglia regions, offering superior sensitivity, robustness to imaging variability, and enhanced detection of biologically relevant age-related associations. These findings support its application in large-scale studies and clinical research to advance our understanding of PVS contributions to CSVD and dementia.