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IMAGE INTERPRETATION · RENAL AND GENITOURINARY

Renal Cortical Scar on DMSA Scan

Tc-99m DMSA renal cortical scan at 30 min and 3 hours (POST, RAO, LAO views) showing focal cortical defect — renal scarring post-pyelonephritis
Tc-99m DMSA renal cortical scan at 30 min and 3 hours (POST, RAO, LAO views) showing focal cortical defect — renal scarring post-pyelonephritis

Provided clinical image

Question

A Tc-99m DMSA (dimercaptosuccinic acid) renal cortical scan is performed in a child after a urinary tract infection. The scan shows a focal area of decreased uptake in the upper pole of the left kidney. This finding is MOST consistent with:

  1. ALeft renal artery stenosis causing upper pole ischemia
  2. BRenal cortical scar (pyelonephritic scar) from prior pyelonephritis — DMSA is the gold standard for detecting cortical scarring
  3. CWilms' tumor (nephroblastoma)
  4. DHydronephrosis
Show the answer and explanation

B. Renal cortical scar (pyelonephritic scar) from prior pyelonephritis — DMSA is the gold standard for detecting cortical scarring

Tc-99m DMSA is the gold standard for detecting renal cortical scarring after pyelonephritis. DMSA is taken up by functioning renal tubular cells and retained in the cortex, so areas of cortical scar (replaced by fibrous tissue with non-functioning tubules) appear as focal photopenic defects. In children, UTIs can cause pyelonephritis and subsequent cortical scarring leading to hypertension and chronic kidney disease — making DMSA scanning essential for follow-up after febrile UTI. DMSA can also detect acute pyelonephritis (areas of decreased uptake that may recover). Sensitivity for cortical scar is >90%. DMSA also measures differential (split) renal function.

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