Fetal Brain Volumes in Complete Vascular Ring: A Cross-Sectional MRI Study.

BACKGROUND: The association between complete vascular ring (CVR) and prenatal brain development remains poorly characterized. OBJECTIVE: To compare global and regional fetal brain volumes between fetuses with CVR and controls, accounting for gestational age (GA), fetal sex, and estimated fetal weight. METHODS: In this retrospective single-center study, 70 prenatally diagnosed CVR fetuses and 200 GA-matched controls with normal brain anatomy (22-37 weeks) underwent 1.5-T fetal MRI. Motion-corrected three-dimensional brain reconstructions were generated by slice-to-volume registration, and 19 regions were automatically segmented using a deep-learning pipeline. Linear regression included continuous GA, group, their interaction, fetal sex, and estimated fetal weight. Regional-to-intracranial volume ratios and sensitivity analyses incorporating maternal body mass index were evaluated. Multiple comparisons were controlled using the Benjamini-Hochberg procedure. RESULTS: At the 28-week reference age, adjusted supratentorial brain, cortical gray matter, white matter, thalamic, lentiform nucleus, brainstem, and lateral ventricular volumes were smaller in the CVR group (all false-discovery-rate-adjusted P<0.05). Intracranial volume did not differ significantly. Thalamic, lentiform nucleus, brainstem, and lateral ventricular proportions were also smaller. No group-by-GA interaction survived correction in the primary model. CONCLUSIONS: CVR was associated with differences in selected fetal brain volumes, including regional differences relative to intracranial volume. Larger longitudinal studies with postnatal follow-up are needed.