Quantitative and qualitative evaluation of volume of low osmolality contrast medium needed for routine helical abdominal CT

OBJECTIVE. The purpose of our study was to determine the minimum optimal do se of IV contrast medium for helical CT that can preserve image quality whi le reducing cost. SUBJECTS AND METHODS. Four hundred sixty-three patients f r om six centers were enrolled in a prospective trial in which patients wer e randomized into one of four weight-based dose categories of iopromide, 30 0 mg I/mL: 1.25. 1.50, 1.75, and 2.0 mL/kg. Six of 463 patients were exclud ed from analysis. A radiologist at each center who was unaware of the volum e of contrast medium administered determined whether the scans were accepta ble. The responses were analyzed by dose, in aggregate. and by weight. Enha ncement values (in Hounsfield units) in regions of interest in the liver, p ancreas, aorta, and kidneys were obtained at a single time during the scan. The participating radiologist was unaware of these values. Finally, three additional nonparticipating site observers assessed the images for acceptab ility. diagnostic quality, and overall level of confidence. A cost mt,del c omparing incurred charges in using 150 or 100 mL, or 1.5 mL/kg, of low osmo lality contrast medium was developed from experience in an additional 303 p atients. RESULTS. We found no clinically significant difference in acceptability of scans at doses greater than 1.5 mL/kg. However, significant variability occ urred among the centers, The use of 1.5 mL/kg led to a savings of $9977.16 for 303 patients when compared with the use of 150 mL at list price. The co st is the same for 1.5 mL/kg or use of 100 mt of contrast medium. CONCLUSION. A weight-based dose at 1.5 mL/kg of low osmolality contrast med ium can provide acceptable scans in most patients, with a significant cost savings.