To test the hypothesis that cardiac and coronary catheterization can be successfully performed under real-time MR guidance with a conventional x-ray angiographic catheter through application of the appropriate MR imaging technique.

Twelve farm pigs were used. All experiments were conducted on a 1.5 T MR system (Magnetom Sonata), and were performed under a protocol approved by our institutional animal care and use committee. After acquisition of a localizer, a near-real-time True-FISP sequence (TR/TE/Tip/Thickness: 2.33ms/1.17ms/40°/10mm; 3 frames/sec) was used to track the tip of the catheters. A pigtail catheter was used on all animals for both left heart and right heart catheterizations. An Amplatz catheter was used for right coronary artery catheterizations; right heart catheterizations were attempted in 7 animals. All catheters used were manufactured by Cordis. The intravascular devices were visualized by means of their native susceptibility artifacts. Approximately 5-10ml of 25% diluted Gadolinium-DTPA contrast material was injected to confirm engagement of the right coronary artery during right coronary artery catheterizations.

Cardiac catheterization of both the right and left heart were successfully performed in all 12 pigs. The catheter tip as well as the longitudinal profile of the catheter was readily visible as signal void on the real-time True FISP images. In addition, right coronary catheterization was successfully completed in 6 of 7 pigs attempted. With injection of 25% diluted Gadolinium, the right coronary artery can be visualized as a dark curvilinear structure. The average time for either left heart catheterization (including ascending aorta and left ventricle), or right heart catheterization (including right atrium and ventricle), was one minute, while the time range required for coronary artery catheterization was 30-90 minutes.

Cardiac catheterization was feasible with passive visualization using only the native susceptibility effect of selected conventional X-ray angiographic catheters under real-time MR guidance. Coronary catheterization was also achievable under real-time MR guidance.

J.S.L.,J.L.D.,S.Z.,S.R.,Y.C.: Supported by a grant from Siemens Medical Solutions