Preliminary study of pulmonary three-dimensional time-of-flight MR angiography with breath-holding using a contrast medium.

Pulmonary three-dimensional (3D) time-of-flight (TOF) MR angiography with breath-holding using a paramagnetic contrast medium and a 1.5 Tesla superconducting MR system was performed on a volunteer and five patients with hilar or mediastinal tumors in order to visualize the main pulmonary arteries. Six MR scans (one before and five after a Gd-DTPA injection) were obtained using fast imaging with a steady-state precession (FISP) sequence while the subjects held their breath. The acquisition time was 21 seconds, and images were obtained every 30 seconds. In the normal volunteer, the pulmonary MR angiogram obtained in the first postcontrast scan was successful in visualizing the main pulmonary artery, and its right and left branches to the level of the lobar branches. In the five patients, at the first postcontrast scanning, the pulmonary arteries had higher signal intensities than the surrounding structures. Therefore, during this imaging period, most tumors could be clearly distinguished from vessels. In images made much later after contrast medium injection, the pulmonary arteries could not be distinguished from the others. Pulmonary 3D TOF MR angiography with breath-holding using a contrast medium is very useful in demonstrating pulmonary vessels and tumors.