Comparison of bolus and constant infusion methods of gadolinium administration in MR angiography.

PURPOSE To determine whether the method of delivery of gadolinium can alter optimal small-vessel detail in MR angiography. METHODS Six healthy volunteers were studied with MR angiography using both a constant infusion and a bolus method of contrast administration to a total dose of 0.1 mmol/kg. Both three-dimensional time-of-flight and 3-D phase-contrast techniques were used. RESULTS Constant infusion did not prove superior to bolus administration of contrast. With both techniques, gadolinium enhancement uniformly improved visualization of small vessels. Delay from the time of contrast administration to scan acquisition decreased vessel enhancement. CONCLUSIONS Bolus administration of gadolinium is sufficient to improve small vessel visualization with MR angiography. When a series of contrast-enhanced images is to be obtained, MR angiographic sequences should be obtained first.