NML KIDNEY

Phases of contrast in renal/ureteral imaging:

• NECT: used to assess for intralesional fat, renal stones, parenchymal calcs, hemorrhage. Also provides baseline attenuation of renal lesions.

• Arterial (20-40 sec): Performed to evaluate renal vasculature; primarily for surgical planning. There is significant corticomedullary differentiation.

• Nephrogenic (100 sec): evaluate renal parenchyma (neoplasm, scarring, inflammation). Renal parenchyma appears homogeneous.

• Excretory phase (8-15 min): assess for urothelial abnormalities (calyceal diverticulum, papillary necrosis, tumors, stricture). lasix can be given to maximix contrast excretion. This phase can obscure ureteral stones.

Absent nephrogram

• absence of normal renal parenchymal enhancement in the renal fossa.

• DDX for unilateral absent nephrogram: renal agenesis, ectopic kidney, surgically absent kidney, or an abnormall kidney that is present but does not enhance (acute renal artery/vein occlusion, chornic ureteral obstruction, congenital or acquired renal dz resulting in nonfunctioning nephrons)

Unilateral renal enlargement

• Pyelonephritis

• Acute ureteral obstruction

• Renal vein thrombosis

• Compensatory hypertrophy