Magnetization transfer magnetic resonance imaging of parenchymal lung disease

Rationale and Objectives. Magnetic resonance imaging with magnetization transfer (MT) contrast recently has been described as a method that may provide additional information about the macromolecular composition of tissue. Magnetization transfer contrast images were compared to conventional gradient-recalled echo images in a variety of pulmonary parenchymal diseases and normal lung. Methods. Single-slice gradient echo images were obtained with and without an off-resonance radio frequency pulse on a 0.1T MR scanner. The change in signal intensity between identical regions of interest on non-MT and MT images was determined in 13 patients with known lung disease, five healthy volunteers, and three postmortem atelectatic dog lungs. Results. No significant change in signal intensity (MT effect) was observed in fat, flowing blood, normal lung, atelectatic lung, or in acute pulmonary edema. Chronic parenchymal lung disease showed the greatest MT effect, 37.7% ± 7.5. Acute infectious lung disease showed an intermediate degree of MT effect, 19.5% ± 3.0. Conclusions. Magnetization transfer contrast magnetic resonance imaging of pulmonary disease is feasible at low field strength and may be useful in the characterization and differentiation of pulmonary parenchymal abnormalities. Magnetization transfer contrast appears to be proportional to the amount of interstitial fibrosis in lung parenchyma, while acute inflammatory cell infiltration exhibits less MT effect and acute pulmonary edema exhibits very little.