• 99mTc-DMSA has a high affinity for the renal cortex
• 99mTc-DMSA is the preferred radiopharmaceutical for static parenchymal imaging
• Provides the most accurate assessment of relative renal function compared to other tracers
Following tracer injection, 99mTc-DMSA is mostly plasma protein bound, and therefore clearance by GFR is minimal. In the kidney, the cells of the proximal convoluted tubules (and the distal tubules to a lesser extent) extract the 99mTc-DMSA by tubular secretion allowing slow concentration of radioactivity in the renal cortex. After 3 hours, about 50% of the injected tracer is concentrated in the kidneys, remaining there for up to 24 hours. The majority of the other 50% is excreted unchanged in urine. Increased hepatic accumulation, and subsequent biliary excretion is noted in patients in renal failure. Owing to the slow renal extraction of 99mTc-DMSA, the optimal time for imaging is between 2 and 4 hours after tracer injection.
99mTc-DMSA scanning represents functioning tubular mass, yields excellent cortical images, and is an invaluable tool in the assessment of both adults and children.
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