Lung Perfusion In Pulmonary Hypertension - Results From The Respire Study

Introduction: PAH is a heterogeneous disease that affects cardiac output and results in lung perfusion deficits. Dynamic contrast-enhanced MRI (DCE-MRI) has shown utility in identifying abnormalities in PAH, however its clinical utility in PAH is not yet proven. Aims: To assess relative pulmonary blood volume (rPBF), flow (rPBF), transit time (rMTT) and full width at half maximum (FWHM) in the lungs of healthy controls and patients with PAH using first pass DCE-MRI. Methods: DCE-MRI images from 17 patients with PAH and 10 healthy controls, a subset of the RESPIRE study, were analysed retrospectively, at two visits (1-12 months apart). Patients were separated into those initiating/escalating PAH therapy (Patient Group 1) and those who had no change in treatment (Patient Group 2). Results: Relative pulmonary blood volume (rPBV), flow (rPBF) and mean transit time (rMTT) (Fig1) demonstrated utility in differentiating controls from patients with PAH, as did the heterogeneity of FWHM. Lung perfusion metrics could also detect change between visit 1 and visit 2 in patient group 1, whereas established right ventricular cardiac MRI measures could not. Conclusions: Based on this retrospective analysis, lung perfusion measures may be more sensitive to treatment-induced change in PAH than established RV cardiac metrics. Acknowledgements: NIHR (RP-R3-12-027), MRC (MR/M008894/1) and GlaxoSmithKline (PJCH: BIDS3000032592, RESPIRE study: COL100041816) for funding.