The Synthesis and Evaluations of the 68Ga-Lissamine Rhodamine B (LRB) as a New Radiotracer for Imaging Tumors by Positron Emission Tomography

Purpose. The aim of this study is to synthesize and evaluate Ga-68-labeled Lissamine Rhodamine B (LRB) as a new radiotracer for imaging MDA-MB-231 and MCF-7 cells induced tumor mice by positron emission tomography (PET). Methods. Firstly, we performed the radio synthesis and microPET imaging of Ga-68(DOTA-LRB) in athymic nude mice bearing MDA-MB-231 and MCF-7 human breast cancer xenografts. Additionally, the evaluations of F-18-fluorodeoxyglucose (FDG), as a glucose metabolism radiotracer for imaging tumors in the same xenografts, have been conducted as a comparison. Results. The radiochemical purity of Ga-68(DOTA-LRB) was >95%. MicroPET dynamic imaging revealed that the uptake of Ga-68(DOTA-LRB) was mainly in normal organs, such as kidney, heart, liver, and brain and mainly excreted from kidney. The MDA-MB-231 and MCF-7 tumors were not clearly visible in PET images at 5, 15, 30, 40, 50, and 60 min after injection of Ga-68(DOTA-LRB). The tumor uptake values of F-18-FDG were 3.79 +/- 0.57 and 1.93 +/- 0.48% ID/g in MDA-MB-231 and MCF-7 tumor xenografts, respectively. Conclusions. 68Ga(DOTA-LRB) can be easily synthesized with high radiochemical purity and stability; however, it may be not an ideal PET radiotracer for imaging of MDR-positive tumors.