Slice-to-Volume Registration of the Fetal Thorax to Assess Observed/Expected Total Fetal Lungs Volume in Fetuses with Congenital Diaphragmatic Hernia Who Underwent Fetoscopic Endoluminal Tracheal Occlusion.

INTRODUCTION

The objectives of this study were to evaluate the feasibility of slice-to-volume registration (SVR) of the fetal thorax in congenital diaphragmatic hernia (CDH) and to compare observed-to-expected total fetal lung volume (O/E TFLV) obtained from original and SVR MRI volumes for prediction of postnatal survival.

METHODS

We retrospectively analyzed 35 fetuses with CDH undergoing MRI before and after fetoscopic endoluminal tracheal occlusion (FETO). High-resolution, motion-corrected SVR volumes were reconstructed using an automated pipeline. O/E TFLV was measured on both original and SVR volumes, and results were compared between survivors and non-survivors at 6 months of age. Agreement, correlation, and predictive accuracy were assessed using Pearson correlation and ROC analysis.

RESULTS

Four (11.4%) cases were excluded due to uncorrectable artifacts or technical issues. SVR reconstruction required only three acquisitions versus a median of six for conventional imaging. Post-processing took a median of 14 min, and lung delineation was longer for SVR than for original volumes. O/E TFLV measurements showed good to very good agreement between original and SVR volumes (r = 0.75 before and r = 0.96 after FETO), with comparable predictive accuracy for survival (AUC original = 0.81-0.83 vs. AUCSVR = 0.83, p > 0.7).

CONCLUSION

SVR of the fetal thorax is feasible in CDH and provides reliable O/E TFLV measurements with prognostic accuracy comparable to conventional MRI, while reducing the need for repeated acquisitions.