[Ultrafast MRI phlebography of the lungs]

Improved detection of pulmonary-venous pathologies by imaging the pulmonary veins without arterial overlay.

Sequential 3D imaging of the pulmonary arterial and arteriovenous phase was performed with an ultrafast 3D FLASH sequence successively acquiring eight 3D data sets every 2.9 s within a single breathhold. For an 8 cm thick 3D slab an interpolated spatial resolution of about 1.4 x 1.9 x 3.3 mm could be achieved. Different protocols for contrast media dose and infusion rate were used. For selective visualization of the pulmonary veins, the pulmonary arterial phase was subtracted from a subsequent arteriovenous phase with the highest venous signal. 5 healthy volunteers, 8 patients with history of a cerebrovascular accident (CVA) of unknown etiology an suspected pulmonary-venous thrombosis and 9 patients with compression of the pulmonary vasculature by centrally growing malignancies were evaluated.

With higher infusion rate and lower contrast media dose, arteries and veins could be better separated by their enhancement kinetics. In all cases a complete visualization of the main pulmonary veins, segmental and subsegmental veins up to the fourth order of each lung segment was achieved without any overlay of pulmonary arteries. No thrombi of the pulmonary veins were found in patients with CVA. The obstruction of pulmonary arteries and veins due to vessel compression could be selectively visualized.

Ultrafast multiphase 3D-Gd-MRA is a new reliable method for selective 3D visualization of pulmonary veins.