Tc-99m MAG3
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Tc-99m MAG3 (mercaptoacetyltriglycine) is one of the technetium radiopharmaceuticals used in renal imaging.
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 paediatric 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
- paediatric dose: 3.7 MBq/kg (0.10 mCi/kg) (minimum: 14.8 MBq (0.4 mCi)) 5
- 60 sec flow study; then every 5 min for 25 min
- +<li>technetium oxidation state: +5</li>
-<li>cannot measure <a title="Estimated glomerular filtration rate (eGFR)" href="/articles/estimated-glomerular-filtration-rate">GFR</a> as it is cleared almost entirely by tubular secretion</li>- +<li>cannot measure <a href="/articles/estimated-glomerular-filtration-rate">GFR</a> as it is cleared almost entirely by tubular secretion</li>
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