Magnetic Resonance Imaging Assessment of Pulmonary Vascularity in Infants with Congenital Diaphragmatic Hernia: A Novel Tool for Direct Assessment of Severity of Pulmonary Hypertension and Hypoplasia

Objectives To assess the feasibility of magnetic resonance imaging (MRI) for postnatal assessment of pulmonary vascularity in infants with congenital diaphragmatic hernia (CDH). Study design Infants with prenatally diagnosed CDH (n = 24) received postnatal pulmonary MRI. Infants with non-pulmonary birth defects served as controls (n = 5). Semiautomatic segmentation was performed to obtain total vascular volume using time of flight images to assess vascularity. Results Average vascular density (vascular volume/lung volume) in control infants was 0.23 +/- 0.06 mm(3)/mm(3) compared with 0.18 +/- 0.06 mm(3)/mm(3) in infants with CDH is (P = .09). When stratified further based on CDH severity, the difference between control infants and moderate CDH group was statistically significant. (0.23 mm(3)/mm(3) vs 0.15 mm(3)/mm(3), P= .01). Ipsilateral vascular density on MRI in infants with CDH significantly correlated with the prenatal pulmonary hypertensive index (P = .0004, Spearman R = +0.87) and with number of days on mechanical ventilation (P = .04, Spearman R = -0.44), total days on inhaled nitric oxide (P = .02, Spearman R = -0.47), use of epoprostenol for acute pulmonary hypertension (PH) (0.14 mm(3)/mm(3) vs 0.20 mm(3)/mm(3) , P = .005), and use of sildenafil for chronic PH (0.15 mm(3) /mm(3) vs 0.19 mm(3) /mm(3), P = .03). Conclusions Our results suggest that postnatal pulmonary vascularity assessed by MRI strongly correlates with prenatal and postnatal markers of PH severity and that pulmonary vascularity may serve as a direct measure of pulmonary vascular hypoplasia in infants with CDH.