Objective: To evaluate the diagnostic value of cardiac magnetic resonance (CMR) imaging parameters in connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH), assess the feasibility of predicting mean pulmonary artery pressure (mPAP), and explore correlations between CMR parameters and serological markers.

Methods:Clinical data from 34 patients with CTD-PAH, confirmed by right heart catheterization and who underwent CMR within 14 days at Tianjin Medical University General Hospital, were retrospectively analyzed. The diagnostic performance of CMR parameters was examined in relation to the clinical characteristics of CTD-PAH.

Results:Among the 34 CTD-PAH patients, 17 had systemic lupus erythematosus (SLE), 9 had primary Sjögren's syndrome (pSS), 6 had systemic sclerosis (SSc), and 2 had mixed connective tissue disease (MCTD). Twenty-two healthy individuals served as controls. Compared with controls, right ventricular mass index, right ventricular end-systolic volume index, right ventricular ejection fraction, tricuspid annular plane systolic excursion, and tricuspid annular–apex distance change all showed strong discriminatory ability. Notably, right ventricular mass index, right ventricular end-systolic volume index, and right ventricular ejection fraction each had an AUC > 0.9, and their combined use further improved diagnostic accuracy. A CMR-based prediction model for mPAP was established: mPAP (mmHg) = 8.125 + 0.313 × systolic deformation time percentage of the interventricular septum (%) + 0.248 × right ventricular mass (g).RVMM and RVMMI correlated significantly and positively with right ventricular pressure (RVP) measured by right heart catheterization (RHC). The percentage of interventricular septum (IVS) deformation was proportional to RVP, right ventricular end-diastolic pressure (RVEDP), and pulmonary vascular resistance (PVR). A significant positive correlation was observed between ESSDAI scores and late gadolinium enhancement (LGE) volume.

Conclusion:CMR possesses the ability to diagnose, and even achieve early diagnosis of CTD-PAH, and it has clinical application value in assessing the disease condition and predicting the prognosis. In specific clinical scenarios, especially among patient groups who cannot tolerate right heart catheterization or have contraindications to invasive procedures, CMR is expected to serve as an alternative diagnostic option to RHC. In future clinical practice, greater emphasis should be placed on the application of CMR in the diagnosis and treatment of CTD - PAH.