OP03.01: Relationship between lung area at ultrasound and lung volume with magnetic resonance imaging (MRI) in isolated congenital diaphragmatic hernia (CDH)

Abstract

To prospectively examine the relationship between contralateral lung area by two-dimensional ultrasound and contralateral and total fetal lung volume (FLV) by MRI in the assessment of fetuses with isolated CDH. Sixty-six fetuses with isolated CDH were included. Contralateral fetal lung area was measured by 2D ultrasound (longest axis method). Ipsilateral, contralateral and total FLV were measured using multiplanar axial T2-WI MRI. Regression analysis was used to determine the significance of the association between contralateral lung area and total FLV and subsequently the predicted total FLV was calculated using a regression equation. Univariate regression analysis was used to investigate the effect on the proportionate difference between the predicted and the observed total FLV of gestational age (GA), proportionate volume of ipsilateral vs. total FLV, side of CDH, intrathoracic herniation of the liver and intra-tracheal presence of the balloon. Sixty-six fetuses underwent a total of 191 paired 2D ultrasound and MRI examinations at a median GA of 30 (range, 18–38) weeks. It was possible to visualize and measure the contralateral lung area by 2D ultrasound as well as both the ipsilateral and contralateral lung volumes by MRI in all instances. There was a significant association between contralateral lung area and total FLV (r = 0.84; P < 0.001). Univariate regression analysis showed that the proportionate difference between the predicted and the observed total FLV was significantly associated with the proportionate volume of ipsilateral vs. total FLV but not with GA, side of CDH, intrathoracic herniation of the liver or intra-tracheal presence of the balloon. In CDH, contralateral lung area measurement by 2D ultrasound correlates well with total FLV by MRI irrespective of GA, liver herniation or side of herniation. Inconsistencies between both measurements are attributable to the contribution of the ipsilateral lung to the total FLV.