• Brian E Schirf, Jordin D Green, Kent Sato, Andrew C Larson, Ali Shaibani, Riad Salem, Debiao Li, and Reed A Omary.
• Department of Radiology, Northwestern University, Suite 700, 448 East Ontario St., Chicago, IL 60611, USA. b-schirf@med.northwestern.edu
• Acad Radiol. 2005 Jun 1; 12 (6): 771-5.

Rationale And ObjectivesTo determine the optimal gadolinium concentration for catheter-directed coronary magnetic resonance angiography (MRA) using magnetization-prepared steady-state free-precession (SSFP) in swine.Materials And MethodsIn six pigs, we performed real-time MR imaging-guided coronary artery catheterization using a 1.5 T MR scanner. For catheter-directed coronary MRA, we injected 3-4 mL of dilute Gd at 1 mL/second for each tested concentration (4%, 8%, 10%, and 12% Gd). Eleven images per concentration were acquired using electrocardiographic-triggered, magnetization-prepared two-dimensional (2D) projection SSFP. We compared mean relative signal-to-noise ratio (SNR) values for each concentration using two-way analysis of variance.ResultsThe targeted coronary artery was catheterized under real-time MR guidance in all pigs. Magnetization-prepared 2D projection SSFP successfully depicted the coronary arteries in all 44 injections. Mean relative SNR (+/- standard error) was 7.2 +/- 0.49 for 4%, 8.8 +/- 0.47 for 8%, 9.5 +/- 0.38 for 10%, and 8.8 +/- 0.41 for 12%. Injections of 4% dilute gadolinium yielded significantly less relative SNR than the other tested concentrations (P < .05). There were no statistically significant differences between the remaining concentrations.ConclusionFor catheter-directed contrast-enhanced coronary MRA, the ideal gadolinium concentration should maximize relative SNR and limit the total gadolinium dose. Using these criteria, of those concentrations we tested in the swine model, 8% injected gadolinium was superior for catheter-directed SSFP coronary MRA.

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