Gadolinium as a CT contrast agent: Assessment in a porcine model

PURPOSE: To investigate the use of gadolinium as a computed tomographic (CT ) contrast agent. MATERIALS AND METHODS: In vitro attenuation measurements of multiple diluti ons of gadodiamide and ioversol were compared. In three pigs, 50-mL boluses of undiluted gadodiamide were injected intravenously at 2 mL/sec, and repe ated single-level scans were obtained through the lung bases, liver, and ki dneys. The doses of 0.8-1.0 mmol of gadolinium per kilogram of body weight were approximately three times the highest doses currently used in patients . Enhancement was determined from attenuation measurements in the aorta, pu lmonary arteries, liver, and kidneys. RESULTS: In vitro, the attenuation of undiluted gadodiamide (3,069 HU) was equivalent to that of ioversol diluted to 106 mg of iodine per milliliter a nd at equimolar concentrations was 50% greater than that of ioversol. The m agnitude of and time to peak enhancement were 141 HU and 27 seconds (n = 3) for the aorta; 168 HU and 21 seconds (n = 3) for the pulmonary arteries; 2 3 HU and 65 seconds (n = 2) for the liver; and 63 HU and 32 seconds (n = 1) for the kidneys. Time-attenuation curves revealed a useful duration of enh ancement of 20-30 seconds for the aorta and pulmonary arteries. CONCLUSION: Gadolinium produces good vascular enhancement, adequate renal e nhancement, and suboptimal hepatic enhancement. Further study is needed to determine the safety of the gadolinium dose required to produce similar enh ancement in patients.