Renal cortical retention on delayed CT after angiography and contrast associated nephropathy

The aim of this study was to examine the relationship between renal cortical retention (RCR) of contrast media observed on delayed CT (median delay: 20 h) and contrast associated nephropathy (CAN). We investigated the incidence of both phenomena in 270 patients. CAN was defined as an increase in the creatinine level > 0.5 mg dl-1 (44 mumol l-1) and > 25% on day 1, 3 or 7, while RCR was recognized when CT values for the renal cortex showed either mild RCR (CT value > 50) or severe RCR (CT value > 100). RCR was demonstrated in 127 patients (47%), mild in 78 (29%) and severe in 49 (18%), on delayed CT after angiography. CAN was found in eight patients (3%). Patients with severe RCR showed a higher CAN rate (8%) than other patients (mild RCR: 4%, RCR (-): 1%) (p = 0.02). The type of contrast medium was independently associated with the incidence of RCR (p = 0.0001). Although severe RCR was associated with a higher frequency of CAN than the milder forms of RCR, RCR as such was not always associated with CAN.