MR angiography with gadopentetate dimeglumine-polylysine: evaluation in rabbits.

Flow in high-resistance peripheral vessels of the extremities is characterized by a short period of positive flow during systole and almost no flow during diastole. Hence, time-of-flight sequences for MR angiography in high-resistance peripheral vessels are successful only when applied in a plane perpendicular to the vessel course. When applied in a plane parallel to the vessel, the method suffers from the rapid saturation of the inflowing spins. Gadopentetate dimeglumine-polylysine is a new T1 relaxation agent with blood-pooling capability that can be used to prevent blood saturation. In the present study it produced excellent angiograms in rabbits at a dose of 0.01-0.08 mmol/kg injected IV. Time-of-flight angiograms were acquired in a 1.5-T superconducting magnet with a three-dimensional fast imaging with steady precession sequence, 20,40/10/20 degrees (TR/TE/flip angle), with an acquisition volume of 200 x 200 x 60 mm, 64 partitions, and velocity compensation in the slice-selection and frequency-encoding directions. Arteries and veins smaller than 1 mm were visualized over the entire length of the posterior limbs. If ongoing studies confirm the low toxicity of this new agent, gadopentetate dimeglumine-polylysine could offer a totally new approach to MR angiography.