Presentation
COVID-19 with severe sepsis and acute renal failure. Abdominal radiograph obtained for abdominal pain.
Patient Data
Both the left and right renal parenchyma is radiodense. There is also opacification of the right renal calyces and pelvis (a tiny amount in the left renal calyces as well).
Partially-visualized nasogastric and feeding tubes. Wires from cardiac pads in the left hemiabdomen as well.
Case Discussion
If intravenous iodinated contrast is administered to a patient with severe renal injury, there is the potential that the contrast will collect in the poorly (or non-) functioning tubules in the nephrons of the renal parenchyma. If the contrast collects in the tubules and upper collecting system and is not excreted, then future noncontrast imaging will show "enhancement" which is really just residual contrast.
In this case, the patient had a CT of the abdomen and pelvis with IV contrast 12 hours earlier. The vast majority of the IV contrast should have been filtered by the nephrons and excreted into the collecting system and bladder (the half-life of this particular contrast agent is 2 hours). Since it is still visible on an abdominal radiograph (a persistent nephrogram), this implies that the kidneys are poorly-functioning, compatible with renal injury.