Purpose or Case Report: Esophageal atresia (EA) is a relatively rare congenital anomaly. Esophageal pouch (EP) is the only direct sign of EA on fetal MRI, but is not always seen. Distended hypopharynx (DHP) has been reported as a useful prenatal sign of EA, but as EP and DHP are both subjective assessments, the prenatal diagnosis of EA is challenging. The aim of this study was to evaluate whether quantitative measurement of distended pharynx is useful in the diagnosis of EA.
Methods & Materials: From our radiology database, we selected 27 fetuses with suspected EA or obvious EA, all of whom underwent MRI with 1.5T scanners between 2002 and 2022. The 27 cases were divided into EA and non-EA groups according to the presence or absence of EA as recorded in their medical records, which were also reviewed for comorbidities other than EA, and Gross classification in the EA group. Two radiologists independently evaluated balanced steady-state free precession (bSSFP) or single-shot turbo spin-echo (SSTSE) sagittal images for EP and coronal images for DHP. The anteroposterior diameters of the pharynx (P) and foramen magnum (F) were measured and the P/F ratio was calculated. We investigated the sensitivity and specificity of EP and DHP, and calculated the mean values and distributions of the P/F ratio for each group. ROC curve analysis was performed to identify the best P/F ratio cutoff value for diagnosis of EA.
Results: Of the 27 cases, 15 were classified as EA and 12 as non-EA. In the EA group, 12 were Gross type C and 3 were Gross type A.VATER/VACTERL association was 46.7% in the EA group and 0% in the non-EA group, chromosomal abnormalities were present in 13.3% in the EA group and 50.0% in the non-EA group, and other morphological abnormalities were present in 26.7% in the EA group and 50.0% in the non-EA group.
The sensitivity, specificity, and kappa coefficient for EP were 90%, 95.8%, and 0.85, respectively, and those for DHP were 76.7%, 58.3%, and 0.68; EP was more sensitive, specific, and reproducible than DHP. Median P/F ratio was significantly higher in the EA group (1.34, IQR: 1.24 - 1.61) compared to the non-EA group (0.82, IQR: 0.55 - 1.07) (p < 0.001). The P/F ratio cutoff value for diagnosis of EA was 1.20 (AUC=0.91).
Conclusions: Addition of the quantitative P/F ratio to the qualitative EP findings may improve the diagnostic performance of fetal MRI for Addition of the quantitative P/F ratio to the qualitative EP findings could improve the diagnostic performance of fetal MRI for EA.