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

The association between complete vascular ring (CVR) and prenatal brain development remains poorly characterized.

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.

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.

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.

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.