Persistent CT nephrogram: significance in the diagnosis of contrast nephropathy--an update.

Contrast nephropathy (CN), a well-known complication of intravascular contrast medium, is associated with dense cortical nephrograms. These may be detected on unenhanced computed tomography (CT). We report the initial findings of a series of patients at risk for CN who received contrast for coronary arteriography or aortic arch angiography. Unenhanced CT scans were performed 22-26 h after contrast, and the mean cortical attenuation measured. These results were correlated with serial blood urea nitrogen (BUN) and serum creatinine measurements. The patients in this study, all of whom had either elevated baseline creatinine values, were over 73 years or both, had a high incidence of cortical contrast retention and contrast nephropathy.