Pulmonary T2* quantification of fetuses with congenital diaphragmatic hernia: a retrospective, case-controlled, MRI pilot study.

Background: Advanced MRI techniques, motion-correction and T2*-relaxometry, may provide information regarding functional properties of pulmonary tissue. We assessed whether lung volumes and pulmonary T2* values in fetuses with congenital diaphragmatic hernia (CDH) were lower than controls and differed between survivors and non-survivors.

Methods: Women with uncomplicated pregnancies (controls) and those with a CDH had a fetal MRI on a 1.5 T imaging system encompassing T2 single shot fast spin echo sequences and gradient echo single shot echo planar sequences providing T2* data. Motion-correction was performed using slice-to-volume reconstruction, T2* maps were generated using in-house pipelines. Lungs were segmented separately using a pre-trained 3D-deep-learning pipeline.

Results: Datasets from 33 controls and 12 CDH fetuses were analysed. The mean ± SD gestation at scan was 28.3 ± 4.3 for controls and 27.6 ± 4.9 weeks for CDH cases. CDH lung volumes were lower than controls in both non-survivors and survivors for both lungs combined (5.76 ± 3.59 [cc], mean difference = 15.97, 95% CI: -24.51--12.9, p < 0.001 and 5.73 ± 2.96 [cc], mean difference = 16, 95% CI: 1.91-11.53, p = 0.008) and for the ipsilateral lung (1.93 ± 2.09 [cc], mean difference = 19.8, 95% CI: -28.48--16.45, p < 0.001 1.58 ± 1.18 [cc], mean difference=20.15, 95% CI: 5.96-15.97, p < 0.001). Mean pulmonary T2* values were lower in non-survivors in both lungs, the ipsilateral and contralateral lungs compared with the control group (81.83 ± 26.21 ms, mean difference = 31.13, 95% CI: -58.14--10.32, p = 0.006; 81.05 ± 26.84 ms, mean difference = 31.91, 95% CI: -59.02--10.82, p = 0.006; 82.62 ± 36.31 ms, mean difference = 30.34, 95% CI: -58.84--8.25, p = 0.011) but no difference was observed between controls and CDH cases that survived.

Conclusions: Mean pulmonary T2* values were lower in CDH fetuses compared to controls and CDH cases who died compared to survivors. Mean pulmonary T2* values may have a prognostic function in CDH fetuses.

Impact: This study provides original motion-corrected assessment of the morphologic and functional properties of the ipsilateral and contralateral fetal lungs in the context of CDH. Mean pulmonary T2* values were lower in CDH fetuses compared to controls and in cases who died compared to survivors. Mean pulmonary T2* values may have a role in prognostication. Reduction in pulmonary T2* values in CDH fetuses suggests altered pulmonary development, contributing new insights into antenatal assessment.