CO2 microbubble contrast enhancement in x-ray angiography.

Aim To demonstrate that carbon dioxide (CO 2 ) microbubble contrast enhancement depicts blood vessels when used for x-ray examinations. Materials and methods Microbubbles were generated by cavitation of physiological saline to which CO 2 gas had been added using an ejector-type microbubble generator. The input pressure values for CO 2 gas and physiological saline that produced a large quantity of CO 2 microbubbles were obtained in a phantom. In an animal study, angiography was performed in three swine using three types of contrast: CO 2 microbubbles, conventional CO 2 gas, and iodinated contrast medium. For CO 2 microbubble contrast enhancement, physiological saline, and CO 2 gas were supplied at the input pressures calculated in the phantom experiment. Regions of interest were set in the abdominal aorta, external iliac arteries, and background. The difference in digital values between each artery and the background was calculated. Results The input pressures obtained in the phantom experiment were 0.16 MPa for physiological saline and 0.5 MPa for CO 2 gas, with physiological saline input volume being 8.1 ml/s. Three interventional radiologists all evaluated the depictions of all arteries as “present” in the CO 2 microbubble contrast enhancement, conventional CO 2 contrast enhancement, and iodinated contrast enhancement performed in three swine. Digital values for all vessels with microbubble CO 2 contrast enhancement were higher than background values. Conclusions In x-ray angiography, blood vessels can be depicted by CO 2 microbubble contrast enhancement, in which a large quantity of CO 2 microbubbles is generated within blood vessels.