Gd-DTPA-polylysine-enhanced pulmonary time-of-flight MR angiography

The enhancing effect of gadolinium diethylenetriaminepentaacetic acid (DTPA) polylysine (a macromolecular paramagnetic contrast agent) in time-of-flight magnetic resonance (MR) angiography of isolated perfused sheep lungs was studied. Unilateral lung damage was induced with hydrochloric acid in eight sheep. The heart and lungs were removed from the thoracic cavity, and after cannulation of the trachea and both ventricles, pulsatile perfusion and ventilation were initiated. The heart-lung preparations were placed in the head coil of a 1.5-T imager. Time-of-flight pulmonary MR angiography was performed during respiratory arrest, before and after administration of 0.02 mmol/kg Gd-DTPA-polylysine. On the postcontrast angiograms, the signal intensity increased by 120% in pulmonary arteries (P < .01). The contrast-to-noise ratio between pulmonary arteries and parenchyma increased significantly (P < .01). The number of visualized generations of pulmonary artery branches increased from four to six in normal lungs and from three to five in edematous lungs. Low-dose Gd-DTPA-polylysine significantly improves the conspicuity of the pulmonary vascular tree in time-of-flight pulmonary MR angiography.