OP05.10: Fetal magnetic resonance imaging (MRI) versus 3D ultrasonography (3D‐US) in assessment of fetal lung volumes in cases at risk of pulmonary hypoplasia

Abstract

To analyse the correlation and agreement between 3D-US & MRI in measuring fetal lung volumes in cases at risk of developing pulmonary hypoplasia. 38 fetuses at high risk of developing lung hypoplasia either due to extrathoracic causes like renal anomalies causing oligohydraminos and skeletal dysplasias with narrow chest (22cases) or due to intrathoracic causes like congenital cystic adenomatoid malformation (CCAM) and congenital diaphragmatic hernia (CDH) (16 cases) were involved in a cross sectional study. 3D volume data sets of the fetal lungs were acquired were using a commercially available ultrasound system & total lung volumes were calculated using the virtual organ computer-aided analysis (VOCAL) method. MRI obtained fast T2 weighted images of fetal chest in axial, coronal and sagittal planes with assessment of signal intensity & lung volumetry. Comparison between mean lung volumes was performed using unpaired t test. Agreement between the 3D-US and MRI methods was done using Cohen Kappa test. Finally sensitivity, specificity, positive predictive value, negative predictive value & diagnostic accuracy were calculated for 3D-US and for MRI. Good agreement was detected between the two methods(Kappa = 0.715, p = 0.001). The measured lung volumes by 3D-US were smaller than those measured by MRI (p >0.05, non-significant). MRI showed greater specificity, positive predictive value and diagnostic accuracy (100%each) than 3D-US (68.75,78.26 &82.86%) respectively. There is good concordance between 3D-US and MRI in measuring lung volumes and in assessment of pulmonary hypoplasia. MRI can be used complementary to US in borderline cases of pulmonary hypoplasia and in difficult diagnostic situations due to complicated lesions or due to technical problems as in cases of severe oligohydraminos & improper fetal position.