[Magnetic resonance angiography of the pulmonary artery. Preliminary considerations]

The possibility was evaluated of imaging the pulmonary artery with MR angiography. Twenty healthy volunteers were studied using 3D FT gradient-echo sequences on the coronal plane, with post-processing by the maximum intensity projection method. TE and TR remaining short, flip angles were selected to increase pulmonary artery signal in contrast with hypointense adjacent tissues and vessels. Flip angle selection allowed the optimal differentiation between pulmonary artery and aorta with 15 degree-25 degree angles (range: 110.7 to 122 for the 15 degree flip angle and 158.7 to 182.1 for the 20 degree flip angle). The sequence was obtained on the coronal plane and the following parameters were employed: TR 0.03 s, TE 10 ms, flip angle 15 degree-20 degree, slice of the total volume 100 mm with 64 partitions, 256 x 256 matrix, 1 zoom factor, 1 acquisition. The patient was positioned with the right hemithorax raised by 30 degrees to visualize the common pulmonary artery and lying on his back, face upward, to visualize the right and left pulmonary arteries. Post-processing employed axial plane rotations from -45 degrees to +45 degrees, with 5 degrees step, and from 0 degrees to 180 degrees, with 15 degrees step. Angio-MR images of the pulmonary artery allowed the visualization of its main components, up to its right and left lobar branches. The main limitation of this technique consisted in its poor spatial resolution.