Clinical investigations of Tc-99m-p-aminohippuric acid as a new renal agent

Abstract

Objective Tc-99m-p-aminohippuric acid (PAH) is a new radiopharmaceutical rapidly secreted by the kidneys in a manner consistent with tubular secretion. A comparative study of renal scintigraphy and clearance with Tc-99m-PAH, diethylene triamine pentaacetic acid (DTPA) and mercaptoacetyltriglycine (MAG(3)) was performed. Methods (TC)-T-99m-PAH was prepared from a lyophilized kit by addition of sodium pertechnetate in the presence of DTPA. Ten healthy individuals were injected with 110 MBq of Tc-99m-PAH. A dynamic study was repeated with Tc-99m-DTPA and Tc-99m-MAG(3) several days later, after a 1-day interval. Clearance measurements were performed in five individuals. Results The mean values of time-to-peak activity (T-max) and the time from peak to 50% of peak activity (T-1/2) for Tc-99m-PAH (3.6 +/- 0.9 and 6.9 +/- 2.7 min, respectively) and Tc-99m-MAG, (3.5 +/- 0.8 and 6.8 +/- 2.1 respectively) were significantly lower in comparison with those of Tc-99m-DTPA (4.9 +/- 1.7 and 11.7 +/- 1.9 min, respectively). The mean value of Tc-99m-PAH clearance (186.9 +/- 12.2 ml/min) was significantly lower in comparison with MAG(3) clearance (303.9 +/- 19.5 ml/min) and significantly higher than DTPA clearance (85.0 +/- 24.1 ml/min). Conclusion Our preliminary results indicate the potential usefulness of Tc-99m-PAH for routine renal scintigraphy. Owing to its fast kinetics, excretion and high-quality images, it could be a suitable for Tc-99m-DTPA. Tc-99m-PAH clearance values, however, were significantly lower than those of MAG(3), and could not be used for the estimation of renal plasma flow. Nucl Med Commun 30:76-81 (C) 2009 Wolters Kluwer Health vertical bar Lippincott Williams and Wilkins.