Background/aim  

The research on congenital diaphragmatic hernia (CDH) is often carried out on the nitrofen fetal rat model in which most investigations involve microdissections and fastidious assessment of serial sections of different anatomic areas. Current microscopic magnetic resonance (MMR) equipment allows detailed anatomic studies of alive, fresh or fixed fetuses. The purpose of the present study was to demonstrate that CDH itself and most of the associated malformations are adequately imaged and measured by MMR.

Materials and methods  

Fetuses from pregnant rats treated with either i.g. vehicle (control, n = 10) or 100 mg nitrofen (only those with CDH, n = 18) on E9.5 were recovered on E21 (term = E22) and total body was scanned by MMR under sedation in a 7 T MRI system (Bruker Medical, Ettlingen, Germany). CDH was detected with a coronal multislice fast spin echo sequence with a long repetition time and short effective echo time. Oblique MPR and 3D reconstructions were used. All studies were processed with attention to the hernia and its contents and the structure of the tracheobronchial tree and the lung, the heart and great vessels, the thymus and cervico-thoracic vertebrae. The findings in both groups were compared.

Results  

Congenital diaphragmatic hernia, lung hypoplasia and parenchymal features were clearly depicted. Tracheal ring anomalies were also demonstrated. The thymus was significantly smaller in CDH pups (2.9 × 1 × 2.4 mm) than in controls (4 × 1.3 × 2.8 mm) (p < 0.01). MRI was particularly performant for imaging cardiovascular anomalies: 4 double aortic arches, 3 Fallots, 3 right aortic arches, 3 ventricular septal defects and 1 aberrant subclavian artery.

Conclusions  

Microscopic magnetic resonance involves refined and expensive equipment but it provides a powerful research tool for the study of CDH and other malformations in rat fetuses. Further work on this area is warranted.