Purpose: This preliminary study investigates changes in white matter hyperintensities (WMH) and lesion counts in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). The primary objective was to assess pre- and post-surgical differences in WMH volumes and lesion counts using brain magnetic resonance imaging (MRI) Fluid-Attenuated Inversion Recovery (FLAIR) 3D sequences.

Methods: The first fifteen patients of the PASCAL study were included. Brain MRI scans were performed before surgery and within 10 days post-operatively. WMH volumes and lesion counts were assessed using automatic segmentation (Quantib ND) with semi-automatic adjustments by a neuroradiologist and a trained radiographer. A paired t-test was used to compare pre- and post-surgical values, and reproducibility was evaluated using a Bland-Altman analysis.

Results: The mean pre-operative WMH volume was 0.49 cm³, increasing to 0.57 cm³ post-operatively (p = 0.044). The lesion count increased from 13 to 14 (p = 0.09). The Bland-Altman analysis for WMH volume demonstrated a mean difference of 0.04 cm³ (limits of agreement: -0.15 to 0.23 cm³), indicating acceptable agreement between methods. For lesion counts, the mean difference was 1, with limits of agreement ranging from -5 to 7, suggesting moderate variability. Despite the observed changes, the overall magnitude of WMH volume increase was small, and lesion count variations remained within measurement variability.

Conclusions: These findings suggest that WMH volume may increase after CPB surgery, while lesion counts remain relatively stable. Further analysis with a larger cohort is needed to confirm these preliminary results and assess the clinical implications of post-operative WMH changes.