Semi-quantitative analysis of Right Ventricular Myocardial First-pass Perfusion Using Cardiac Magnetic Resonance Imaging in Systemic Sclerosis and Pulmonary Arterial Hypertension.

Abstract

Background: Right ventricular (RV) myocardial perfusion has been touted as a primary mechanism to understand impairment in RV function in patients with pulmonary arterial hypertension (PAH). However, measuring RV perfusion presents technical challenges. In this study, our aim is to employ a semi-quantitative approach using cardiac magnetic resonance (CMR) imaging to measure RV free wall first-pass perfusion in patients with PAH and controls, and to evaluate the intra- and inter-reader reproducibility of this approach.

Methods: This study included 37 subjects (mean age 58.2±12 years, 72.9% female), 8 with idiopathic pulmonary arterial hypertension (IPAH), 10 with systemic sclerosis (SSc) and pulmonary arterial hypertension (PAH), 12 with SSc without PAH, and seven healthy controls. All participants underwent rest and adenosine stress perfusion CMR imaging using a 3 T scanner as part of a research protocol for evaluating pulmonary hypertension. Two readers delineated three regions of interest (ROIs) within the visible RV myocardium and manually traced contours of endocardial and epicardial borders of the left ventricle (LV) in two planes. Semi-quantitative perfusion analysis was performed with dedicated software for the measurement of first-pass myocardial perfusion. Concordance correlation coefficients (CCC) assessed inter- and intra-reader agreement of measurements.

Results: Patients had an RV Ejection fraction (EF) of 50.9±11.3% and LVEF of 63.8±6.4 % and controls had an RVEF of 61.3±6.7 % and LVEF of 65.5±5.1 %. RV myocardial perfusion measurements at rest and stress were similar between the two readers (2.29±1.17 (mL/g × min) and 2.77±1.44 (mL/g × min) at rest, 4.02±2.45 (mL/g × min) and 4.35±2.72 (mL/g × min) during stress. The agreement was best for stress phase (0.90), followed by rest phase (0.83), and myocardial perfusion reserve index (MPRI) (0.72). The agreement was higher between readers for LV perfusion measurements (rest phase: 0.97, stress phase: 0.99, and MPRI: 0.89). RV MPRI was significantly higher in controls (2.62±0.73) as compared to all patients (1.63±0.75). The differences remained when controls were compared to patients with PAH.

Conclusion: Semi-quantitative first-pass RV perfusion reserve measures are technically feasible and show excellent inter-reader agreement. RV perfusion reserve index was lower in patients with PAH compared to healthy controls.