Geometric morphological parameters from cardiac magnetic resonance imaging in assessment of chronic pulmonary thromboembolism, a prospective pilot study

Abstract Objective The role of geometric-morphological parameters derived from cardiac magnetic resonance imaging (CMR) in assessing and stratifying chronic pulmonary thromboembolism (CPTE) remains unclear. Material and methods We prospectively enrolled 53 CPTE patients (16 with chronic thromboembolic pulmonary disease (CTEPD), 37 with chronic thromboembolic pulmonary hypertension (CTEPH)) and 53 age- and sex-matched healthy controls. All patients underwent CMR and right heart catheterization within 24 h. Biventricular fractal dimension (FD) and perimeter-area ratio (PAR) were quantified on short-axis cine images at end-diastole and end-systole across basal, mid, and apical levels. Group comparisons, ROC analysis, and Spearman correlations were performed. Incremental diagnostic value was assessed using multivariable logistic regression, net reclassification improvement, and integrated discrimination improvement. Results Right ventricular (RV) FD was significantly higher and RVPAR lower in CTEPH, most pronounced at the apical level, both in end-diastole and end-systole ( p < 0.05). Apical RVFD and RVPAR robustly differentiated CPTE from controls (AUC = 0.911–0.961) and CTEPH from CTEPD (AUC = 0.819–0.895). Both parameters provided significant incremental diagnostic value over RVEF. In univariable analysis, RVFD correlated positively with afterload indices and negatively with perfusion/output metrics; RVPAR showed inverse associations (all p < 0.05). Multivariable linear regression showed that RVPAR retained weak independent negative associations with mean pulmonary arterial pressure and pulmonary vascular resistance. Conclusion CMR-derived apical RVFD and RVPAR reflect early, load-dependent ventricular remodeling in CPTE and demonstrated potential as complementary non-invasive imaging markers for severity assessment and risk stratification, highlighting the apex as the most sensitive site of RV adaptation. Key Points Question The role of CMR-derived fractal dimension and perimeter-area ratio in assessing right ventricular remodeling and differentiating CTEPH from CTEPD remains unclear. Findings Apical RVFD and RVPAR differentiated CPTE from controls (AUC 0.911-0.961) and CTEPH from CTEPD (AUC 0.819-0.895), correlated with PVR and mPAP, and provided incremental diagnostic value over RVEF. Relevance statement This pilot study suggests that cine-derived fractal dimension and perimeter-area ratio can characterize right ventricular remodeling, correlate with invasive hemodynamics, and provide incremental diagnostic value over conventional functional indices.