What organ receives the highest dose during a Tc mertiatide (MAG-3) scan?

• A. Heart
• B. Liver
• C. Bladder
• D. Kidneys

Answer: (C)

The organ that receives the highest radiation dose during a Tc mertiatide (MAG-3) scan is the bladder. This is primarily due to the pharmacokinetics of MAG-3, which is designed for renal imaging and is predominantly excreted through the kidneys into the urinary tract. As the radiopharmaceutical concentrates in the urine, the bladder receives a significant dose because the radiotracer remains present for a period of time while the bladder fills.

In renal scans, the kidneys do absorb a considerable amount of the administered dose; however, since the MAG-3 is primarily eliminated through urination, the bladder experiences the highest cumulative dose as it retains the radioactive material. This retention is crucial for imaging but also results in an increased radiation exposure to the bladder wall, thus distinguishing it as the organ with the highest radiation dose during the scan.