Automated Fetal Intracranial Volume Z-Scores and Multi-Vessel Doppler Velocimetry for the Assessment of Fetal Brain Growth in Severe Fetal Growth Restriction: A Retrospective Cross-Sectional Study

Abstract Objective. To evaluate automated three-dimensional fetal intracranial volume (ICV) measurement, alone and combined with multi-vessel Doppler indices, for assessing fetal brain growth in severe fetal growth restriction (FGR), and to quantify its repeatability. Methods. This retrospective cross-sectional study included 111 examinations in 110 women with severe FGR and 235 controls undergoing automated ICV measurement (Smart ICV) and multi-vessel Doppler assessment. ICV, estimated fetal weight (EFW), and Doppler indices were expressed as gestational-age-adjusted Z-scores. Analyses included group comparisons, ROC analysis, bootstrap-validated logistic models, repeatability assessment, and external-reference validation. Results. ICV Z-score was lower in severe FGR than in controls (− 2.27 ± 1.55 vs − 0.05 ± 1.08; P < 0.0001), as was EFW Z-score; the brain–body dissociation index (ICV Z minus EFW Z) was + 2.06 vs − 0.08 (P < 0.0001), consistent with adaptive head sparing. ICV Z-score discriminated severe FGR from controls with an AUC of 0.907 (95% CI 0.876–0.935; sensitivity 82.0%, specificity 85.4%). In the Doppler subset, the combined ICV + cerebroplacental ratio (CPR) model achieved an AUC of 0.923 with good calibration (optimism-corrected AUC 0.918), without significant improvement over ICV alone (P = 0.118). Repeatability was excellent (ICC 0.998, within-subject CV 1.98%). External-reference Z-scores correlated strongly with internal values (r = 0.910). Conclusion. Automated ICV Z-scoring demonstrates high diagnostic performance for identifying reduced fetal brain growth in severe FGR and reveals head sparing; adding CPR yields a well-calibrated model without significant incremental discrimination. Automated ICV volumetry is a promising adjunct to Doppler surveillance; prospective outcome-linked validation is warranted.