MR imaging-guided vascular procedures using CO2 as a contrast agent

OBJECTIVE. The purpose of this study was to test the use Of CO2 as a black blood contrast agent for MR imaging-guided vascular procedures in an animal model. MATERIALS AND METHODS. Repeated intraarterial CO2 injections were per-formed through a catheter located in the aorta and the renal arteries of three fully anesthetized pigs. Real-time images were acquired using a steady-state free precession sequence. RESULTS. During the CO2 injections, the bright blood in the aorta and the main renal artery was totally replaced, and this procedure resulted in an immediate, statistically significant signal loss in the vessel lumen. In more peripheral vessels, CO2 improved the vessel conspicuity substantially. Confirmation of vessel patency distal to the catheter tip position was possible. CONCLUSION. The use of carbon dioxide in combination with a bright blood MR imaging sequence improves vessel conspicuity and provides immediate information about blood flow distal to the catheter. This technique may be used to facilitate MR imaging-guided intravascular procedures.