Purpose: This study aimed to investigate the effect of ursodeoxycholic acid (UDCA) on the biodistribution and excretion of technetium-99m (Tc-99m)-labeled radiopharmaceuticals. Materials and Methods: Tc-99m hydroxy-methylene-diphosphonate (HDP), Tc-99m pertechnetate, and Tc-99m dimercaptosuccinic acid (DMSA) were injected via the tail vein of rats. After 30 min, the control group was administered saline, and the UDCA group was given UDCA orally. Scintigraphy images were acquired after 30 min and 1, 2, 3, and 4 h. Radioactivity and rate of change were compared. Tc-99m mercaptoacetyltriglycine (MAG3) imaging was also performed. Results: In image analysis of Tc-99m HDP, radioactivity of the buttock was lower in the UDCA group at 4 h. Rates of change in the buttock were significantly different at 3 h–30 min and 4 h–30 min, and buttock radioactivity in the UDCA group had decreased more. In analysis of Tc-99m pertechnetate, radioactivity of the buttock was higher in the control group. Rates of change in the thyroid gland and buttock were different at 1 h–30 min, 3 h–30 min, and 4 h–30 min, with radioactivity in the UDCA group decreasing more. In the analysis of Tc-99m DMSA, while the radioactivity of the kidneys in the control group showed little decrease at 1 h–30 min, that in the UDCA group increased. In the analysis of Tc-99m MAG3 images, radioactivity and radioactivity/total body radioactivity (TBA) values for the kidneys were higher in the UDCA group at 2 min. At 5 and 10 min, radioactivity/TBA values for soft tissue in the UDCA group were lower than those in the control group. Conclusion This study demonstrated that administration of UDCA increases renal excretion and soft tissue clearance of radiopharmaceuticals. This investigation could contribute to the broadening of applications of UDCA.

Purpose: This study aimed to investigate the effect of ursodeoxycholic acid (UDCA) on the biodistribution and excretion of technetium-99m (Tc-99m)-labeled radiopharmaceuticals. Materials and Methods: Tc-99m hydroxy-methylene-diphosphonate (HDP), Tc-99m pertechnetate, and Tc-99m dimercaptosuccinic acid (DMSA) were injected via the tail vein of rats. After 30 min, the control group was administered saline, and the UDCA group was given UDCA orally. Scintigraphy images were acquired after 30 min and 1, 2, 3, and 4 h. Radioactivity and rate of change were compared. Tc-99m mercaptoacetyltriglycine (MAG3) imaging was also performed. Results: In image analysis of Tc-99m HDP, radioactivity of the buttock was lower in the UDCA group at 4 h. Rates of change in the buttock were significantly different at 3 h–30 min and 4 h–30 min, and buttock radioactivity in the UDCA group had decreased more. In analysis of Tc-99m pertechnetate, radioactivity of the buttock was higher in the control group. Rates of change in the thyroid gland and buttock were different at 1 h–30 min, 3 h–30 min, and 4 h–30 min, with radioactivity in the UDCA group decreasing more. In the analysis of Tc-99m DMSA, while the radioactivity of the kidneys in the control group showed little decrease at 1 h–30 min, that in the UDCA group increased. In the analysis of Tc-99m MAG3 images, radioactivity and radioactivity/total body radioactivity (TBA) values for the kidneys were higher in the UDCA group at 2 min. At 5 and 10 min, radioactivity/TBA values for soft tissue in the UDCA group were lower than those in the control group. Conclusion This study demonstrated that administration of UDCA increases renal excretion and soft tissue clearance of radiopharmaceuticals. This investigation could contribute to the broadening of applications of UDCA.

Purpose: The objective of this study was to describe to develop methods of rodent leukocyte isolation and radiolabeling for in vivo inflammation imaging. Methods: Thigh muscle inflammation was induced by injection of collagenase. Blood was collected from the jugular vein and separated by Histopaque. The collected cells were incubated in a 37 °C CO2 incubator for 1~2 h. After incubation, 99mTc-HMPAO and 18F-FDG were used to treat leukocytes followed by incubation for 30 min. 99mTc-HMPAO and 18F-FDG labeled autologous leukocytes were injected into the tail veins of rats. The images were then acquired at various time points. Image-based lesion to normal muscle ratio was compared. Results: After Histopaque separation, the proportion of lymphocytes was higher than that of other cell types. After CO2 incubation, the collected leukocytes were viable, while room temperature exposed leukocytes without CO2 incubation were non-viable. Granulocytes, especially, were more quickly influenced by various conditions than the mononuclear cells. Labeling efficiencies of 99mTc-HMPAO and 18F-FDG were 4.00 ± 2.06 and 1.8%, respectively. 99mTc-HMPAO- and 18F-FDG-labeled leukocytes targeted well the inflamed lesion. 99mTc-HMPAO-labeled leukocytes, but not 18F-FDG-labeled leukocytes, were found in the abdomen activity. Conclusion Inflamed lesions of rats were well visualized using autologous radiolabeled leukocytes. This method might provide good information for understanding inflammatory diseases.