Paintbrush sign - Intravenous urography

Case contributed by Mohammad Taghi Niknejad
Diagnosis almost certain


Work up for hematuria.

Patient Data

Age: 20 years
Gender: Female

In a non-contrast image, no nephrolithiasis or renal parenchymal calcification could be identified. After contrast media administration, exaggerated stranded enhancement of the medullary pyramids is evident bilaterally, better seen on the zoomed images, resembling a paintbrush sign.

Case Discussion

A paintbrush sign on IVU or CT-IVU describes the streaky appearances of dilated contrast filled tubules within the renal medulla, suggesting medullary sponge kidneys or renal tubular ectasia (which the patient was confirmed to have).

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