MAG3

Tc-99m MAG3 (mercaptoacetyltriglycine) is one of the technetium radiopharmaceuticals used in renal imaging. Due to favorable energy and dosimetric characteristics, MAG3 radiolabeled with technetium has replaced the iodide-131 Hippuran for the study of renal function (tubular secretion physiology) .

Characteristics

• photon energy: 140 KeV
• physical half-life: 6 hours
• biological half-life: 4 hours
• technetium oxidation state: +5
• normal distribution: kidneys (100%)
• pharmacokinetics:
  • uptake by tubular secretion (97%)
  • first pass filtration 60%
• excretion: renal via both glomerular filtration and tubular excretion; hence, in pediatric patients and patients with poor renal function this test is considered superior to DTPA scan
• target organ: bladder
• miscellaneous facts
  • good quality images with renal insufficiency
  • by giving captopril, MAG3 plasma clearance decreases in hypertensive patients with renal artery stenosis but increases in patients without renal artery stenosis
  • cannot measure GFR as it is cleared almost entirely by tubular secretion

Uses, doses and timings

• renal study
  • adult dose: 296 MBq (8 mCi) IV
  • pediatric dose: 3.7 MBq/kg (0.10 mCi/kg) (minimum: 14.8 MBq (0.4 mCi))
  • 60-sec flow study; then every 5 min for 25 min

Siehe auch:

• technetium radiopharmaceuticals

und weiter:

• technetium agents
• radiopharmaceuticals