Tc-99m dimercaptosuccinic acid (DMSA) is preferred over Tc-99m MAG3 when looking for acute pyelonephritis or post-infectious renal scarring in a child because:

• A It binds to proximal tubular cells in the cortex, so cortical defects reflect loss of functioning parenchyma ✓
• B It is cleared exclusively by glomerular filtration
• C It concentrates in the adrenal glands and outlines the kidney indirectly
• D It measures urinary drainage after furosemide injection

Explanation

DMSA is retained in the renal cortex by proximal tubular binding, producing a static cortical image in which scars and inflammatory lesions appear as photopenic defects. MAG3 is a dynamic tubular secretory agent used for drainage assessment, so its images are poor for cortical detail. DMSA is not filtered solely by glomeruli, and diuretic washout curves are the domain of MAG3 renography.

Reference: Mettler, Essentials of Nuclear Medicine Imaging, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.