[Clinical assessment of 99mTc-MAG3 scintigraphy for impaired renal function]

The renal scintigraphy and clearance of 99mTc-mercaptoacetyltriglycine (MAG3) and 123I-ortho-iodohippuric acid (OIH) were compared in 12 patients with impaired renal function. The patients were first studied with MAG3 and then reinvestigated with OIH two days later. The MAG3 renal scintigraphy gave better quality and functional information in comparison with OIH. The MAG3 and OIH renogram showed identical relative kidney uptake and Tmax, but T1/2 of MAG3 was longer (p < 0.001). The plasma clearance of MAG3 was lower than that of OIH, but they correlated significantly (r = 0.87, p < 0.005). Also, the plasma clearances of MAG3 and para-aminohippuric acid (calculated by the standard clearance technique) showed good correlation (r = 0.77, p < 0.05). The urinary excretion during the first 60 min after injection was the same for the two radiopharmaceuticals. We conclude that 99mTc-MAG3 is a suitable alternative to 123I-OIH in renal scintigraphy.