The enhancement of the renal parenchyma and the excreted contrast in the upper collecting systems seems like a normal finding... until you realize that this is a noncontrast study which makes the finding a persistent nephrogram. The patient had received intra-arterial contrast for a cardiac procedure over 13 hours earlier; since the biologic half-life of the agent is normally 2.1 hours, this implies that there is renal injury and the administered contrast is moving slowly in the nephrons' tubules into the upper collecting system.