Persistent renal enhancement after intra-arterial versus intravenous iodixanol administration

Purpose: To examine the clinical significance of persistent renal enhancement after iodixanol administration. Methods: We retrospectively studied 166 consecutive patients who underwent non-enhanced abdominopelvic CT within 7 days after receiving intra-arterial (n = 99) or intravenous (n = 67) iodixanol. Renal attenuation was measured for each non-enhanced CT scan. Persistent renal enhancement was defined as CT attenuation >55 Hounsfield units (HU). Contrast-induced nephropathy (CIN) was defined as a rise in serum creatinine >0.5 mg/dL within 5 days after contrast administration. Results: While the intensity and frequency of persistent renal enhancement was higher after intra-arterial (mean CT attenuation of 73.7 HU, seen in 54 of 99 patients, or 55%) than intravenous contrast material administration (51.8 HU, seen in 21 of 67, or 31%, p < 0.005), a multivariate regression model showed that the independent predictors of persistent renal enhancement were a shorter time interval until the subsequent non-enhanced CT (p < 0.001); higher contrast dose (p < 0.001); higher baseline serum creatinine (p < 0.01); and older age (p < 0.05). The route of contrast administration was not a predictor of persistent renal enhancement in this model. Contrast-induced nephropathy was noted in 9 patients who received intra-arterial (9%) versus 3 who received intravenous iodixanol (4%), and was more common in patients with persistent renal enhancement (p < 0.01). Conclusion: Persistent renal enhancement at follow-up non-contrast CT suggests a greater risk for contrast-induced nephropathy, but the increased frequency of striking renal enhancement in patients who received intra-arterial rather than intravenous contrast material also reflects the larger doses of contrast and shorter time to subsequent follow-up CT scanning for such patients.