Purpose: To prospectively compare contrast material-enhanced (CE) magnetic resonance (MR) imaging-derived right-to-left ventricle pulmonary transit time (PTT), left ventricular (LV) full width at half maximum (FWHM), and LV time to peak (TTP) between patients with pulmonary arterial hypertension (PAH) and healthy volunteers and to correlate these measurements with survival markers in patients with PAH.
Materials and methods: This HIPAA-compliant study received institutional review board approval. Written informed consent was obtained from all participants. Forty-three patients (32 with PAH [29 women; median age, 55.4 years], 11 with scleroderma but not PAH [seven women; median age, 58.9 years]) underwent right-sided heart catheterization and 3-T CE cardiac MR imaging. Eighteen age- and sex-matched healthy control subjects (12 women; median age, 51.7 years) underwent only CE MR imaging. A short-axis saturation-recovery gradient-echo section was acquired in the basal third of both ventricles, and right-to-left-ventricle PTT, LV FWHM, and LV TTP were calculated. Statistical analysis included Kruskal-Wallis test, Wilcoxon rank sum test, Spearman correlation coefficient, multiple linear regression analysis, and Lin correlation coefficient analysis.
Results: Patients had significantly longer PTT (median, 8.2 seconds; 25th-75th percentile, 6.9-9.9 seconds), FWHM (median, 8.2 seconds; 25th-75th percentile, 5.7-11.4 seconds), and TTP (median, 4.8 seconds; 25th-75th percentile, 3.9-6.5 seconds) than did control subjects (median, 6.4 seconds; 25th-75th percentile, 5.7-7.1 seconds; median, 5.2 seconds; 25th-75th percentile, 4.1-6.1 seconds; median, 3.2 seconds; 25th-75th percentile, 2.8-3.8 seconds, respectively; P < .01 for each) and subjects with scleroderma but not PAH (median, 6.5 seconds; 25th-75th percentile, 5.6-7.0 seconds; median, 5.0 seconds; 25th-75th percentile, 4.0-7.3 seconds; median, 3.6 seconds; 25th-75th percentile, 2.7-4.0 seconds, respectively; P < .02 for each). PTT, LV FWHM, and LV TTP correlated with pulmonary vascular resistance index (P < .01), right ventricular stroke volume index (P ≤ .01), and pulmonary artery capacitance (P ≤ .02). In multiple linear regression models, PTT, FWHM, and TTP were associated with mean pulmonary arterial pressure and cardiac index.
Conclusion: CE MR-derived PTT, LV FWHM, and LV TTP are noninvasive compound markers of pulmonary hemodynamics and cardiac function in patients with PAH. Their predictive value for patient outcome warrants further investigation.