Assessment of Human Pulmonary Function Using Oxygen-Enhanced T1 Imaging in Patients with Cystic Fibrosis

Abstract

Indirect qualitative MRI of pulmonary function is feasible using the paramagnetic effects of oxygen physically dissolved in blood. In this study, a more quantitative oxygen-enhanced pulmonary function test based on the slope of a plot of R1 vs. oxygen concentration-the oxygen transfer function (OTF)-was developed and tested in a pool of five healthy volunteers and five patients with cystic fibrosis (CF). The lung T1 relaxation rate, R1, under normoxic conditions (room air, 21% O2), and the response to various hyperoxic conditions (40%-100% O2) were studied. Lung T1 in healthy volunteers showed a relatively homogeneous distribution while they breathed room air, and a homogeneous decrease under hyperoxic conditions. Lung T1 in CF patients showed an inhomogeneous distribution while they breathed room air, and the observed lung T1 decrease under hyperoxia depended on the actual state of the diseased lung tissue. In the selected group of CF patients, areas with reduced OTF also showed reduced perfusion, as confirmed by qualitative contrast-enhanced MR pulmonary perfusion imaging. The results demonstrate that this completely noninvasive oxygen-enhanced pulmonary function test has potential for clinical applications in the serial diagnosis of lung diseases such as CF. © 2004 Wiley-Liss, Inc.