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Objective: The reported incidence of contrast-induced acute kidney injury varies widely. Almost no studies have been conducted to quantify the background fluctuation of kidney function of patients receiving iodinated contrast medium. The purpose of this study was a retrospective comparison of the incidence of acute kidney injury among patients undergoing CT with low-osmolar (iohexol) or isoosmolar (iodixanol) contrast medium with the incidence among patients undergoing CT without contrast administration., Materials and Methods: Creatinine concentration and estimated glomerular filtration rate were evaluated for 11,588 patients. Rates of acute kidney injury (defined as a 0.5 mg/dL increase in serum creatinine concentration or a 25% or greater decrease in estimated glomerular filtration rate within 3 days after CT) were compared among groups and stratified according to creatinine concentration and estimated glomerular filtration rate before the imaging examination., Results: In all groups, the incidence of acute kidney injury increased with increasing baseline creatinine concentration. No significant difference in incidence of presumed contrast-induced kidney injury was identified between the isoosmolar contrast medium and the control groups. The incidence of acute kidney injury in the low-osmolar contrast medium cohort paralleled that of the control cohort up to a creatinine level of 1.8 mg/dL, but increases above this level were associated with a higher incidence of acute kidney injury., Conclusion: We identified a high incidence of acute kidney injury among control subjects undergoing unenhanced CT. The incidence of creatinine elevation in this group was statistically similar to that in the isoosmolar contrast medium group for all baseline creatinine values and all stages of chronic kidney disease. These findings suggest that the additional risk of acute kidney injury accompanying administration of contrast medium (contrast-induced nephrotoxicity) may be overstated and that much of the creatinine elevation in these patients is attributable to background fluctuation, underlying disease, or treatment.

Objective: The purpose of this study was to compare hepatic tumor conspicuity on CT after injection of either 150 mL of contrast material or 100 mL of contrast material plus a 50-mL saline chaser., Subjects and Methods: We evaluated 86 hypoattenuating liver metastases in 26 patients. Patients underwent CT in two sessions separated by a mean of 85 days: one time with 150 mL of contrast material and the other time with 100 mL of contrast material followed by a 50-mL saline chaser. The order of the sessions was randomized. Contrast material was administered via power injector and matched for injection rate and delay time. Attenuation values were obtained from normal liver tissue and metastases and from the spleen, kidney, aorta, and inferior vena cava., Results: The 150 mL dose of contrast material caused slightly greater liver and tumor attenuation than 100 mL of contrast material with a chaser (mean hepatic attenuation, 95.6 vs 89.8 H, respectively; p < 0.03, paired t test; mean tumor attenuation, 53.2 vs 49.1 H, respectively; r = 0.71, p = 0.09). The difference in conspicuity of liver lesions was slightly greater with 150 mL than with 100 mL with a chaser (46.8 H vs 44.2 H; r = 0.46, p = 0.08, paired t test), but was of doubtful clinical significance (2.6 H). Kidney, spleen, and vascular structures enhanced more with 150 mL than with 100 mL and a chaser., Conclusion: Using 100 mL of contrast material and a saline chaser did not result in a meaningful difference in liver parenchyma attenuation or lesion conspicuity compared with using 150 mL of contrast medium alone. Routine use of a chaser for abdominal CT may yield cost savings and a decreased risk of contrast nephropathy.

Rationale and Objectives: We compared the safety and imaging efficacy of iodixanol-270 (270 mg I/ml), iodixanol-320 (320 mg I/ml), both of which are isosmolal to blood, and iohexol-300 (300 mg I/ml) for body computed tomography (CT) scanning., Methods: One hundred twenty-six patients from the University of Wisconsin Hospital and Temple University Hospital scheduled to undergo body CT examinations were randomly assigned to receive either iodixanol-270, iodixanol-320, or iohexol-300. Patients were monitored with questioning and vital signs before injection, immediately after injection, and at 24 and 48 hr. Extensive laboratory evaluation also was performed., Results: No serious reactions or deaths occurred in any group. The occurrence of overall minor adverse events (usually warmth, headache, taste distortion, rash) was similar for the different groups. Laboratory results showed no significant difference across groups. There was no significant difference in image quality detected among groups., Conclusion: There was no detectable difference in safety and imaging efficacy among the three contrast groups in this study. However, patients from the University of Wisconsin experienced significantly less injection discomfort with iodixanol-270 than with iohexol-300. Large clinical studies may more definitively determine the presence and nature of the relative advantages of iodixanol compared with currently available ionic and nonionic contrast agents.