Abstract
BACKGROUND: Phase-resolved functional lung (PREFUL) magnetic resonance imaging (MRI) is a reliable, noninvasive method for assessing pulmonary ventilation and perfusion. However, the differences in subgroups of patients with chronic pulmonary embolism (CPE) have not been thoroughly investigated, and there may be significant clinical value in examining noninvasive methods for evaluating hemodynamics and right heart function in patients with CPE. This study aimed to evaluate pulmonary perfusion and ventilation in patients with suspected chronic thromboembolic pulmonary hypertension (CTEPH) via PREFUL MRI and further determined the correlations of these findings with right heart catheterization (RHC), right heart function indicators, and pulmonary function test results. METHODS: A retrospective analysis was performed on patients with suspected CTEPH who were referred to our center between June 2020 and September 2022. All patients underwent RHC or echocardiography, pulmonary angiography (PA), ventilation-perfusion (V/Q) lung scan, or CTPA, with PREFUL MRI being conducted within 2 weeks of these tests. The diagnoses of CTEPH and chronic thromboembolic pulmonary disease (CTED) were established through multidisciplinary team discussions. Mean parameter values from five PREFUL MRI slices were calculated, including normalized perfusion (Q(N)), exclusive perfusion defect percentage (QDP(exc)), total perfusion defect percentage (QDP(tot)), regional ventilation (RV), exclusive ventilation defect percentage (VDP(exc)), total ventilation defect percentage (VDP(tot)), and ventilation/perfusion match defect percentage (VQM(def)). Clinical correlations were assessed through the comparison of PREFUL MRI parameters with hemodynamic data, right heart function indicators, and pulmonary function parameters. RESULTS: In total, 42 patients (26 men and 16 women; mean age 53.5±13.5 years) with suspected CTEPH were analyzed: 31 had CTEPH and 11 had CTED. Significant differences between the two groups were found in Q(N), QDP(exc), QDP(tot), RV, and VDP(exc). VQM(def) demonstrated the best diagnostic performance among all parameters, with a sensitivity of 87%, specificity of 91%, and accuracy of 88%. Q(N), QDP(exc), and QDP(tot) were correlated with mean pulmonary arterial pressure (mPAP; r=-0.490, r=0.539, and r=0.534, respectively; all P values <0.01). QDP(exc) and QDP(tot) were correlated with pulmonary vascular resistance (r=0.369 and r=0.362, respectively; P<0.05). Q(N), QDP(exc), and QDP(tot) also were significantly correlated with right heart function indicators (all P values <0.01). RV was negatively correlated with percent predicted single-breath diffusing capacity of the lung for carbon monoxide (DLCO SB %pred; r=-0.588; P<0.001), and VDP(tot) was negatively correlated with the ratio of forced expiratory volume in 1 s to forced vital capacity (parameter expressed as a percentage of the predicted value) (r=-0.379; P=0.027). CONCLUSIONS: Quantitative parameters obtained from PREFUL MRI were correlated with hemodynamic status and cardiopulmonary function in patients with CTEPH or CTED. PREFUL MRI perfusion parameters demonstrated strong diagnostic performance for CTEPH, indicating their clinical potential.