To assess whether phase-resolved functional lung MRI (PREFUL-MRI) can differentiate pulmonary arterial hypertension (PAH) from chronic thromboembolic pulmonary hypertension (CTEPH) and to compare PREFUL-derived perfusion and ventilation characteristics between the two entities. In this single-center study (January 2024–March 2025), patients with pulmonary hypertension (PH) who underwent PREFUL-MRI, ventilation/perfusion single-photon emission CT/CT (V/Q SPECT/CT), and right-heart catheterization within 1 week were retrospectively enrolled. PREFUL-MRI was acquired with a free-breathing fast spoiled gradient echo sequence to generate perfusion and ventilation maps. PREFUL maps and V/Q SPECT/CT were assessed by four blinded readers. Quantitative PREFUL parameters were compared between PAH and CTEPH, and correlations with hemodynamics were analyzed. Fifty-three PH patients were included (PAH 26, CTEPH 27). All manifested multiple perfusion defects on PREFUL maps. Visual assessment with PREFUL yielded 70% sensitivity and 38% specificity for CTEPH, lower than V/Q SPECT/CT (sensitivity 95%, specificity 95%). CTEPH had higher perfusion defect percentage and lower mean perfusion than PAH (median QDP exclusive 51.9% vs. 24.4%, p < 0.001; QDP total 58.4% vs. 30.85%, p < 0.001; mean perfusion 2.8% vs. 3.9%, p = 0.003). QDP exclusive represents areas with perfusion defects but without ventilation defects, whereas QDP total indicates the overall perfusion defect percentage. Across the cohort, QDP exclusive correlated positively with pulmonary vascular resistance (PVR) (ρ = 0.313, p = 0.031). PREFUL-MRI did not reliably distinguish PAH from CTEPH on visual assessment, although CTEPH exhibited a larger perfusion defect burden. It may be more suitable for functional evaluation of PH rather than for initial differential diagnosis. Question Can phase-resolved functional lung MRI (PREFUL-MRI) noninvasively distinguish pulmonary arterial hypertension (PAH) from chronic thromboembolic pulmonary hypertension (CTEPH), and reflect their hemodynamic severity? Findings PREFUL-MRI showed limited visual discrimination compared to V/Q SPECT/CT; CTEPH exhibited more severe perfusion defects; perfusion defect percentage correlated with pulmonary vascular resistance . Clinical relevance PREFUL-MRI provides radiation- and contrast-free perfusion metrics reflecting hemodynamic burden in pulmonary hypertension. Though suboptimal for initial discrimination in disease subtypes, it supports functional evaluation once the diagnosis is established .
Liu et al. (Tue,) studied this question.