Dynamic contrast enhanced MRI for the evaluation of lung perfusion in idiopathic pulmonary fibrosis
Luis Torres, Kristine E. Lee, Gregory P. Barton, Andrew D. Hahn, Nathan Sandbo, Mark L. Schiebler, Sean B. Fain
Abstract
Background The objective of this work was to apply quantitative and semiquantitative dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) methods to evaluate lung perfusion in idiopathic pulmonary fibrosis (IPF). Methods In this prospective trial 41 subjects, including healthy control and IPF subjects, were studied using DCE-MRI at baseline. IPF subjects were then followed for 1 year; progressive IPF (IPF prog ) subjects were distinguished from stable IPF (IPF stable ) subjects based on a decline in percent predicted forced vital capacity (FVC % pred) or diffusing capacity of the lung for carbon monoxide ( D LCO % pred) measured during follow-up visits. 35 out of 41 subjects were retained for final baseline analysis (control: n=15; IPF stable : n=14; IPF prog : n=6). Seven measures and their coefficients of variation (CV) were derived using temporally resolved DCE-MRI. Two sets of global and regional comparisons were made: control versus IPF groups and control versus IPF stable versus IPF prog groups, using linear regression analysis. Each measure was compared with FVC % pred, D LCO % pred and the lung clearance index (LCI % pred) using a Spearman rank correlation. Results DCE-MRI identified regional perfusion differences between control and IPF subjects using first moment transit time (FMTT), contrast uptake slope and pulmonary blood flow (PBF) (p≤0.05), while global averages did not. FMTT was shorter for IPF prog compared with both IPF stable (p=0.004) and control groups (p=0.023). Correlations were observed between PBF CV and D LCO % pred (r s = −0.48, p=0.022) and LCI % pred (r s = +0.47, p=0.015). Significant group differences were detected in age (p<0.001), D LCO % pred (p<0.001), FVC % pred (p=0.001) and LCI % pred (p=0.007). Conclusions Global analysis obscures regional changes in pulmonary haemodynamics in IPF using DCE-MRI in IPF. Decreased FMTT may be a candidate marker for IPF progression.