Side-specific assessment of lung function in children with congenital diaphragmatic hernia - functional matrix pencil decomposition MRI as a promising diagnostic tool

Objectives: In patients with congenital diaphragmatic hernia (CDH) the exact functional outcome of the affected lung side is still unknown, mainly due to the lack of spatially resolved diagnostic tools. Functional matrix-pencil decomposition (MP-) lung MRI fills this gap as it measures side-specific ventilation and perfusion. We aimed to assess the overall and side-specific pulmonary long-term outcome of patients with CDH using lung function tests and functional MP-MRI. Methods: Thirteen school aged children with CDH (seven with small and six with large defect-sized CDH, defined as >50% of the chest wall circumference being devoid of diaphragm tissue) and thirteen healthy matched controls underwent spirometry, multiple-breath washout and MP-MRI. Main outcomes were forced expiratory volume in 1 second (FEV1), lung clearance index (LCI), ventilation defect percentage (VDP), perfusion defect percentage (QDP). Results: Patients with a large CDH showed significantly reduced overall lung function compared to healthy controls [mean difference; 95%-CIadjusted.: FEV1 (z-score) -4.26 (-5.61 to -2.92), LCI2.5 (TO) 1.12 (0.47 to 1.76), VDP (%) 8.59 (3.58 to 13.60), QDP (%) 17.22 (13.16 to 21.27)] and to patients with a small CDH. Side-specific examination by MP-MRI revealed particularly reduced ipsilateral ventilation and perfusion in patients with a large CDH [mean difference to contralateral side; 95%-CIadjusted.: VDP (%) 14.80 (10.50 to 19.00), QDP (%) 23.50 (1.75 to 45.20)]. Conclusions: Patients with a large CDH showed impaired overall lung function with particular limitation of the ipsilateral side. MP-MRI is a promising tool to provide valuable side-specific functional information in the follow-up of patients with CDH.