Dynamic 19F MRI of pulmonary ventilation in lung transplant recipients with and without chronic lung allograft dysfunction

<bold>Background:</bold> By the time chronic lung allograft dysfunction (CLAD), with its main phenotypes bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS), is diagnosed by pulmonary function testing, irreversible damage to the lung allograft has already occurred. Dynamic ¹⁹F MRI is an emerging technique to detect early changes in ventilation and we compared regional ventilation defects between patients with and without CLAD. <bold>Methods:</bold> Multi breath-hold dynamic ¹⁹F MRI using a 79% perfluoropropane/21% O2 gas mixture was performed in 10 lung transplant recipients, 4 without CLAD and 6 with CLAD (5 BOS, 1 RAS). Gas wash-in and washout dynamics were assessed and a regional lung clearance index (RLCI) was used to quantify regional lung ventilation. <bold>Results:</bold> Compared to stable patients, BOS patients had more regions of reduced ventilation, especially in the periphery, requiring a greater number of breaths to reach complete gas wash-in. Washout was homogeneous and rapid in stable patients but delayed and highly heterogeneous in CLAD. CLAD patients exhibited significant difference in RLCI between central and peripheral lung regions (p=0.0001) and a slower median whole-lung RLCI for washout (p<0.001). FEV1 (% baseline) negatively correlated with ventilation during wash-in, most strongly for the periphery (r=-0.844, p=0.0021), but also for the whole lung, apex and base. <bold>Conclusions:</bold> Dynamic ¹⁹F MRI identified quantifiable differences in regional ventilation between patients with and without CLAD, with significant ventilation defects in CLAD patients. This technique hold potential for early detection of regional ventilation differences in lung transplant patients.