Phase-resolved functional lung MRI detects single-dose and sustained bronchodilator responses in COPD in a randomized crossover trial.
OBJECTIVES: To evaluate the effects of tiotropium/olodaterol (T/O) on phase-resolved functional lung (PREFUL) MRI parameters in hyperinflated chronic obstructive pulmonary disease (COPD) patients and examine correlations with conventional cardiopulmonary and hyperpolarized 129Xe MRI measures. MATERIALS AND METHODS: Retrospective subanalysis of a prospective, randomized, placebo-controlled, crossover trial with open-label extension. Thirty-two patients with moderate-to-severe COPD (61.5 ± 7.7 years; 17 men); 30 completed the MRI extension at 1.5 T. PREFUL analysis yielded regional ventilation (RVent), flow-volume loop correlation metric (FVL-CM), normalized perfusion (QN), ventilation defect percentage (VDP), perfusion defect percentage (QDP), V/Q match metrics (VQM), and pulmonary pulse wave velocity (PWV; post-hoc parameter). Linear mixed-effects models tested treatment effects; correlations were evaluated with Spearman's rank and bootstrap 95% confidence intervals (95% CIs). RESULTS: PREFUL parameters improved after T/O single dose (SD) versus placebo, including improvements in FVL-CM by 4.1 percentage points (pp; 95% CI: 1.0 to 7.3 pp) and QN by 0.4 pp (95% CI: 0.2 to 0.6 pp) and reductions in VDP and QDP, with parallel gains in VQM(Non-Defect) (p < 0.05). PWV decreased after multiple doses (-0.87 m/s, 95% CI: -1.26 to -0.48 m/s). PREFUL MRI baseline values showed significant correlations with pulmonary function tests, cardiac, dynamic contrast-enhanced and 129Xe MRI. SD treatment-induced absolute changes in VDP(FVL-CM) correlated with reductions in residual volume (ρ = 0.41, 95% CI: 0.02 to 0.64). Further correlations were observed between PREFUL MRI and ¹²⁹Xe-derived VDP, apparent diffusion coefficient, and compartment ratios. CONCLUSION: PREFUL MRI sensitively captured immediate SD T/O-induced improvements in V/Q parameters and dose-dependent PWV responses after sustained bronchodilation. KEY POINTS: Question Can phase-resolved functional lung (PREFUL) MRI sensitively capture immediate single-dose and sustain multi-dose effects of tiotropium/olodaterol on ventilation-perfusion and vascular function in COPD patients? Findings Tiotropium/olodaterol improved PREFUL MRI-derived ventilation, perfusion, and V/Q matching parameters after a single dose, with sustained pulmonary vascular improvements after repeated dosing. Clinical relevance PREFUL MRI detected immediate and sustained functional improvements after tiotropium/olodaterol and showed significant correlations with cardiopulmonary tests and hyperpolarized ¹²⁹Xe MRI, supporting its role as a sensitive, radiation-free tool for monitoring COPD treatment response.