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| Comparative study of the somatostatin receptor imaging agent-99mTc-HYNIC-TOCA and 99mTc-P829 in tumor model |
| SUN Xun, AN Rui, LI Shuo, HE Yong, WU Jun, ZHANG Jun |
| Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei Key Labortory of Molecular Imaging, Wuhan 430022, China |
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Abstract Objective: To study and to compare the biological characteristic of 99mTc labeled somatostatin analogue 99mTc-HYNIC-TOCA with 99mTc-P829 in tumor model, and to discuss the possibility of diagnosing tumors with 99mTc-HYNIC-TOCA. Methods: TOCA was labeled with 99mTc using HYNIC as bifunctional chelator, EDDA and tricine as coligand. The nude mice bearing human small cell lung cancer underwent static whole body planar imaging after the injection of 99mTc-HYNIC-TOCA or 99mTc-P829. ROIs were drawn and the radioactivity ratios of target to non-target(T/NT) were calculated in every planar imaging. The dynamic biodistribution study was operated in Kunming mice and the percent uptake ratios(%ID/g) of two imaging agents in different tissue at different time were measured. Results: The radiochemical purity of 99mTc-HYNIC-TOCA could reach 94.2% and keep to 93.5% after 6h at room temperature. In the images of tumor bearing mice, two imaging agent were both mainly concentrated in kidney and tumor. In early images, the ratios of tumor to contralateral limbs(T/C) in 99mTc-HYNIC-TOCA group were higher than which in 99mTc-P829 group. The greatest ratios of T/C in two groups(7.45±0.40 and 5.71±0.69) were gained until 4h post-injection. In Kunming mice, the %ID/g of kidney in both groups were the highest and the half-clearance time in blood were less than 60min. The uptake ratio of 99mTc-P829 in liver was significantly greater than the ratio of 99mTc-HYNIC-TOCA(t=2.17, P<0.05). Conculusion: 99mTc-HYNIC-TOCA and 99mTc-P829 could be highly uptaken in tumor and quickly cleared from blood. Both of these two imaging agents have good prospect in diagnosing tumors with SSTR expression.
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Received: 10 January 2006
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2006, Vol. 17 
