Altered Clearance of Gadolinium Diethylenetriaminepentaacetic Acid Aerosol from Bleomycin-injured Dog Lungs

Abstract

To characterize altered alveolar transfer to solute in bleomycin (BLM)-injured lungs, eight dogs underwent a gadolinium diethylenetriaminepentaacetic acid aerosol (Gd-AS) magnetic resonance imaging study before and on Days 7 and 40 after tracheal instillation of BLM (0.75 mg) in the left lungs. Consecutive fast-gradient echo magnetic resonance imaging was acquired during and after spontaneous inhalation of 200-mM Gd-AS. The slope (Kep) and clearance half-time (T1/2) of logarithmic regression lines for clearance curves were estimated. Histology on Day 40 was compared with that on Day 7 in another three dogs. On Days 7 and 40, Gd-AS deposition was heterogeneously reduced in the affected lungs. On Day 7 with multifocal intraalveolar exudative changes, Kep in affected areas was significantly increased compared with baseline (2.5 x 10(-3) minutes(-1) +/- 0.3 versus 1.7 x 10(-3) minutes(-1) +/- 0.2, p < 0.0001), with significant decrease in T1/2 (121.6 +/- 19.7 minutes vs. 170.4 +/- 15.8 minutes, p < 0.001). However, on Day 40 with multifocal interstitial fibrosis, Kep and T1/2 were recovered toward baseline. BLM-injured lungs can be characterized by accelerated Gd-AS clearance during the acute exudative phase and their recovery during the chronic fibrotic phase. This technique is acceptable for monitoring alveolar transfer changes in BLM-injured lungs.