Biodistribution Characteristics and SPECT Imaging of 99m Tc-RET and 99m Tc-REG in Human Lung Cancer Xenografts

Abstract

Objective:

To investigate the biodistribution and single-photon emission computed tomography (SPECT) imaging of ^99mTc-labeled arginine-glutamic acid-threonine (RET) and arginine-glutamic acid-glycine (REG) in nude mice bearing human lung cancer xenografts.

Materials and Methods:

RET and REG were labeled directly with ^99mTc and their binding efficiency to tumor cells was measured in human nonsmall cell lung cancer H1299 cells. After intravenously injecting ^99mTc-RET and ^99mTc-REG into normal mice and nude mice bearing human lung cancer xenografts, their biodistribution was measured at different postinjection times, and percentages of injected dose per gram tissue (% ID/g) of organs of interest were calculated. The mice bearing H1299 lung cancer xenografts were scanned by SPECT at different times following the ^99mTc-RET or ^99mTc-REG injection.

Results:

The radiochemical purity of ^99mTc-RET and ^99mTc-REG was 93.15%±2.02% and 92.90%±2.86%, respectively. The binding rate of ^99mTc-RET and ^99mTc-REG to H1299 cells was 3.56%±0.37% and 2.32%±0.31%, respectively. The uptake of ^99mTc-RET and ^99mTc-REG in tumor was 4.96±1.05% ID/g at 4 hours postinjection and 1.95±0.73% ID/g at 2 hours postinjection, respectively. Tumors in nude mice could be best imaged at 4.5–6 hours postinjection of ^99mTc-RET.

Conclusion:

^99mTc-RET has a higher binding rate to H1299 cells than ^99mTc-REG and might be used as a potential lung cancer imaging agent.