Prenatal MRI quantitative analysis of the nonlinear morphological changes of the choroid plexus during the progression of fetal ventriculomegaly

To quantify fetal choroid plexus (CP) morphological changes across ventriculomegaly (VM) grades using routine 1.5-T MRI and assess their association with lateral ventricle dilatation. In this retrospective study, 135 singleton fetuses (24–37 weeks’ gestation) were categorized by atrial width (AW): normal, mild VM, moderate VM, severe VM). On coronal T2-weighted images, CP length, width, perimeter, and area were measured. The two-dimensional (2D) CP ratio (CPR-2D) and CP-to-ventricle width ratio were calculated. Analysis of covariance (ANCOVA) adjusted for gestational age and fetal biometrics, and intraclass correlation coefficients (ICC) were used for analysis. Absolute CP measurements exhibited non-linear, stage-specific alterations: CP length and perimeter increased in mild VM, decreased in moderate VM, and increased again in severe VM. CP width progressively decreased until moderate VM before rebounding in severe cases. Conversely, ratio-based indices demonstrated a consistent, monotonic linear decrease as VM severity increased, which remained significant after adjusting for covariates ( p < 0.05). While morphological asymmetry existed, the downward trend of ratios remained consistent for both ventricles. The fetal CP undergoes a non-linear change process during the expansion of the lateral ventricle. However, based on ratio-based indicators, especially CPR-2D, stable and reproducible imaging biomarkers can be provided.