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 performed 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.