Lung volume segmentation in fetal MRI: super-resolution reconstructions improve inter-rater reliability.

Background: Fetal MRI is increasingly used to investigate fetal lung pathologies, and super-resolution (SR) algorithms could be a powerful clinical tool for this assessment. Our goal was to investigate whether SR reconstructions result in an improved agreement in lung volume measurements determined by different raters, also known as inter-rater reliability.

Materials and methods: In this single-center retrospective study, fetal lung volumes calculated from both SR reconstructions and the original images were analyzed. Three radiologists manually segmented the fetal lungs and rated the image quality of all images and reconstructions. Fetal lung volumes were calculated, and the coefficient of variation (CV) was determined for each set of images. Bland-Altman plots were generated, and intraclass correlation coefficients (ICCs) were calculated. A one-sided paired Wilcoxon test was used to compare the fetal lung volume CVs, and a two-sided paired t-test was used to compare the lung volumes. The quality ratings were compared using a two-sided paired Wilcoxon test.

Results: A total of 98 fetal scans with gestational ages from 19 to 37 weeks were evaluated. There was a significantly lower CV in the lung volumes segmented from the SR reconstructions (p < 0.001), and the ICCs of the reconstructions were higher than those determined from the original images. Bland-Altman plots demonstrated better agreement in the SR reconstruction lung volumes. No significant differences in quality ratings or lung volumes were found.

Conclusion: SR reconstructions of the fetal lungs in MRI enabled better inter-rater reliability of fetal lung volume assessment.

Relevance statement: SR reconstructions of the fetal body, obtained through fetal MRI, can be a valuable tool for improving the inter-rater reliability of fetal lung volume measurements, a crucial clinical biomarker for assessing fetal development and predicting pregnancy outcomes.

Key points: Deformable slice-to-volume reconstructions of fetal body MRI could be a valuable clinical tool. Quantitative advantages of fetal body MRI reconstructions need to be proven. Fetal body MRI reconstructions improved inter-rater reliability in lung volume measurements.