Combined pulmonary fibrosis and emphysema: 3D time-resolved MR angiographic evaluation of pulmonary arterial mean transit time and time to peak enhancement

To correlate conventional invasive pressure indexes of pulmonary circulation with pulmonary first-order arterial mean transit time (MTT) and time to peak enhancement (TTP) measured by means of three-dimensional time-resolved magnetic resonance (MR) angiography in patients with combined pulmonary fibrosis and emphysema (CPFE). The study was institutional review board approved. All subjects involved in the study provided written informed consent. Eighteen patients with CPFE were enrolled in this study. Thirteen healthy individuals matched for age and sex served as control subjects. Three-dimensional time-resolved MR angiography was performed by using a 3.0-T MR imager. Regions of interest (ROIs) were drawn manually on first-order pulmonary arteries. Within the ROIs, signal intensity-versus-time curves reflecting the first pass of the contrast agent bolus in the pulmonary vessels were obtained. MTT and TTP were calculated. Pulmonary arterial pressure and pulmonary capillary wedge pressure were measured with a double-lumen, balloon-tipped catheter that was positioned in the pulmonary artery. The mean pulmonary arterial pressure (mPAP) and the pulmonary vascular resistance (PVR) were determined. MTT and TTP values were prolonged significantly in patients with CPFE compared with those in the control subjects (P < .001). Mean TTP and mean MTT correlated directly with mPAP and PVR index (P < .005). At multiple linear regression analysis, MTT was the only factor independently associated with PVR index and mPAP. Three-dimensional time-resolved MR angiography enables determination of pulmonary hemodynamic parameters that correlate significantly with the pulmonary hemodynamic parameters obtained with invasive methods and may represent a complementary tool for evaluating pulmonary hypertension in patients with CPFE.