Dynamic Contrast–Enhanced Magnetic Resonance Imaging in Patients with Pulmonary Arterial Hypertension

Abstract

Dynamic contrast-enhanced (DCE) time-resolved magnetic resonance (MR) imaging is a technique whereby the passage of an intravenous contrast bolus can be tracked through the pulmonary vascular system. The aim of this study was to investigate the prognostic significance of DCE-MR pulmonary blood transit times in patients with pulmonary arterial hypertension (PAH). Seventy-nine patients diagnosed with PAH underwent pulmonary DCE imaging at 1.5 T using a time-resolved three-dimensional spoiled gradient echo sequence. The prognostic significance of two DCE parameters, full width at half maximum (FWHM) of the first-pass clearance curve and pulmonary transit time (PTT), along with demographic and invasive catheter measurements, was evaluated by univariate and bivariate Cox proportional hazards regression and Kaplan-Meier analysis. DCE-MR transit times were most closely correlated with cardiac index (CI) and pulmonary vascular resistance index (PVRI) and were both found to be accurate for detecting reduced CI (FWHM area under the curve [AUC] at receiver operating characteristic analysis = 0.91 and PTT AUC = 0.92, respectively) and for detecting elevated PVRI (FWHM AUC = 0.88 and PTT AUC = 0.84, respectively). During the follow-up period, 25 patients died. Patients with longer measurements of FWHM (P = 0.0014) and PTT (P = 0.004) were associated with poor outcome at Kaplan-Meier analysis, and both parameters were strong predictors of adverse outcome from Cox proportional hazards analysis (P = 0.013 and 0.010, respectively). At bivariate analysis, DCE measurements predicted mortality independent of age, gender, and World Health Organization functional class; however, invasive hemodynamic indexes CI, PVRI, and DCE measurements were not independent of one another. In conclusion, DCE-MR transit times predict mortality in patients with PAH and are closely associated with clinical gold standards CI and PVRI.

Quantitative Magnetic Resonance Imaging of Pulmonary Hypertension

“…It should be noted that such measurements may prove to be useful in the prognostic evaluation and follow-up of patients with PAH [112], with a recent study showing prognostic significance of pulmonary transit times in patients with PAH. Transit time measurements predicted mortality independent of age, gender and WHO functional class; however invasive haemodynamic indices cardiac output, pulmonary vascular resistance and DCE measurements were not independent of one another suggesting that they are closely related [113]. …”

Novel Noninvasive Assessment of Pulmonary Arterial Stiffness Using Velocity Transfer Function

“…Except studies measuring PWV in normal subjects,30, 31 other studies involving PWV and analysis of RV CMR indexes were performed in patients with advanced PAH with overall much higher values of mean pulmonary artery pressure and PVR, thus limiting its clinical use 8, 29, 33, 34. The latter is also true for studies applying the dynamic contrast–enhanced magnetic resonance imaging in pulmonary vascular system in patients with advanced PAH 35, 36. Further studies are required to evaluate the applicability and accuracy of these promising approaches in clinical use, especially in subjects with mildly elevated PVR, with mean PA pressure and PVR values close to the diagnostic thresholds for PAH37 (as it was true for a substantial portion of the cohort in the present work).…”

Fontan Hepatic Fibrosis and Pulmonary Vascular Development

“…Small differences in pulmonary vascular resistance, transmitted to the liver through a Fontan circulation, may affect the temporal development of hepatic fibrosis. As Fick-calculated pulmonary vascular resistance is subject to considerable assumptions, especially in patients with functional univentricular, alternative techniques for determining pulmonary vascular resistance, such as pulmonary flow transit time [26], may need consideration.…”