Factors Affecting the Hepatobiliary Excretion of 99mTc-MAG3: Its Clinical Significance in Routine Renography

Since the approval of mercaptoacetyltriglycine (MAG3) for routine clinical use, reports have appeared about hepatobiliary excretion deleteriously affecting available diagnostic and quantitative information. The purpose of this study was to evaluate gallbladder (GB) uptake of MAG3 in the clinical setting and its effect on the evaluation of relative renal function and imaging. Sixty patients with varying degrees of renal impairment were studied. Routine renal function imaging was followed with anterior and right lateral 3-min abdominal images. Factors such as photolytic degradation, reconstitution steps, (99m)Tc O(4) solution, age, and concentration are discussed. In addition, patient fasting state and radiochemical purity are evaluated. The GB uptake was determined as a percentage of the injected dose. The MAG3 quality control ranged from 90.9% to 99.0%. The GB uptake ranged from 0.0% (not visualized) to 0.71%. The effective renal plasma flow ranged from 88 to 743 mL/min. There was no correlation between the QC and the percentage of GB uptake (r = 0.12). The majority of patients in the nonfasting state showed minimal or reduced GB uptake when compared with the majority of patients in the fasting state. Our data suggest that GB uptake of MAG3 is minimal, with no adverse effects on the diagnostic and quantitative analysis of renal function.