CMR-derived apical right ventricular fractal dimension and perimeter-area ratio reflect early, load-dependent ventricular remodeling in chronic pulmonary thromboembolism 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.
Apical RVFD and RVPAR robustly differentiated CPTE patients from healthy controls with high diagnostic accuracy.
Apical RVFD and RVPAR differentiated CTEPH from CTEPD with moderate-to-good diagnostic accuracy.
Right ventricular fractal dimension was significantly higher and RVPAR was significantly lower in CTEPH compared to other groups.
Both RVFD and RVPAR provided significant incremental diagnostic value over right ventricular ejection fraction (RVEF).
In univariable analysis, RVFD correlated positively with afterload indices and negatively with perfusion/output metrics.
In multivariable linear regression, RVPAR retained weak independent negative associations with mean pulmonary arterial pressure and pulmonary vascular resistance.
The study prospectively enrolled 53 CPTE patients and 53 age- and sex-matched healthy controls, with all patients undergoing both CMR and right heart catheterization.
CMR-derived apical RVFD and RVPAR were interpreted as reflecting early, load-dependent ventricular remodeling in CPTE.
This research examined whether two geometric measurements derived from cardiac MRI scans — fractal dimension (FD, a measure of the complexity of the heart chamber's inner surface) and perimeter-area ratio (PAR, a measure of chamber shape) — could help doctors distinguish between different forms of chronic blood clot disease in the lungs and assess disease severity. The study followed 53 patients with chronic pulmonary thromboembolism (a condition where blood clots persistently block lung vessels) and 53 healthy comparison subjects. All patients had both cardiac MRI and an invasive procedure called right heart catheterization performed within 24 hours of each other, allowing the researchers to directly compare the MRI-based measurements against the gold standard hemodynamic measurements. The study found that measurements taken from the tip (apex) of the right ventricle were particularly useful. These apical measurements could distinguish patients with chronic clot disease from healthy individuals with very high accuracy (AUC 0.911–0.961) and could also separate patients with more severe disease causing elevated lung blood pressure (CTEPH) from those with milder disease (CTEPD) with good accuracy (AUC 0.819–0.895). Importantly, these geometric measurements added diagnostic information beyond the commonly used measure of right heart pumping function (right ventricular ejection fraction), and they correlated with invasive measurements of lung blood pressure and vascular resistance. This research suggests that geometric shape analysis of the right heart from standard cardiac MRI scans — without requiring additional special sequences or contrast agents — could serve as a non-invasive tool to help characterize the severity of chronic lung clot disease and monitor how the right heart is adapting to increased workload. The findings from this pilot study indicate that the tip of the right ventricle may be especially sensitive to the early changes caused by this disease, and these measurements could complement existing assessments used in clinical practice.
Du J, Guo Y, Yu H, Liu A, Xi L, Zhang S, et al.. (2026). Geometric morphological parameters from cardiac magnetic resonance imaging in assessment of chronic pulmonary thromboembolism, a prospective pilot study.. European radiology experimental. https://doi.org/10.1186/s41747-026-00811-1