Comparison of mediastinal shift angles obtained with ultrasound and magnetic resonance imaging in fetuses with isolated left sided congenital diaphragmatic hernia

Abstract

Objectives: To compare ultrasound (US) and magnetic resonance imaging (MRI) in the assessment of mediastinal shift angles (MSAs) in fetuses affected by isolated left congenital diaphragmatic hernia (CDH). The use of MRI-MSA and US-MSA as prognostic factor for postnatal survival in fetal left CDH was also explored.

Methods: This was an observational study of 29 fetuses with prenatally diagnosed isolated left CDH, assessed with both US and MRI examinations between January 2015 and December 2018. The US-MSA measurements performed within 2 weeks from the MRI assessment were considered for the analysis. The primary outcome was the postnatal survival rate.

Results: No significant difference between US and MRI MSAs was detected (p = .419). Among the 29 cases, there were 21 alive infants, for an overall postnatal survival rate of 72.41%. After stratifying for postnatal survival, the best cutoffs with the highest discriminatory power in terms of sensibility and specificity were 42.1° for the US-MSA and 39.1° for the MRI-MSA. The performance of MRI-MSA in predicting postnatal survival was close to that of US-MSA in terms of sensitivity (62.5 versus 50.0%), specificity (80.9 versus 90.5%), positive predictive value (55.6 versus 66.7%), negative predictive value (85.0 versus 82.6%) and accuracy (75.9 versus 79.3%). There was no statistically significant difference between the two modalities (p > .05 for all).

Conclusions: MRI and US can be interchangeably used for the assessment of MSA in prenatally diagnosed isolated left CDH. Moreover, MSA measured by both US and MRI was confirmed to be correlated with perinatal outcome in terms of survival.

Keywords: Congenital diaphragmatic hernia; fetal ultrasound; magnetic resonance imaging; mediastinal shift angle; prenatal diagnosis; pulmonary hypoplasia.