Evaluation of gadobutrol in a rabbit model as a new lanthanide contrast agent for computed tomography.

RATIONALE AND OBJECTIVES

The efficacy of the neutral lanthanide contrast agent gadobutrol was compared to that of the iodinated contrast agent iopromide in rabbits.

METHODS

The computed tomography (CT) attenuation of increasing concentrations of gadolinium (Gd) (gadobutrol) and iodine (I) (iopromide) was measured in Hounsfield units (HU) in aqueous solution at 80, 120, and 137 kV. The peak enhancement (net increase in CT attenuation compared with baseline) and the time-enhancement product in the aorta and in the renal parenchyma of the outer and inner cortex were measured in rabbits over a 5-minute period after the animals were given single intravenous injections of 0.7, 1.0, and 1.5 mmol Gd/kg of gadobutrol and 1.0 and 2.4 mmol I/kg of iopromide.

RESULTS

In vitro, the CT attenuation of gadolinium was 40% higher than that of iodine at equivalent mass concentrations (120 kV). The mean peak enhancements in the aorta after the injections of 0.7, 1.0, and 1.5 mmol Gd/kg and 1.0 and 2.4 mmol I/kg were 216, 313, 591, 224, and 498 HU, respectively. In addition, a 30-second injection of the high dose of gadobutrol resulted in an attenuation profile that was suitable for a three-dimensional reconstruction of the aorta and the renal vasculature.

CONCLUSIONS

Because of the higher CT attenuation of gadolinium compared with that of iodine, the neutral macrocyclic chelate gadobutrol is a more effective contrast agent than iopromide for CT at lower doses of the imaging atom.