The Synthesis and Evaluations of the68Ga-Lissamine Rhodamine B (LRB) as a New Radiotracer for Imaging Tumors by Positron Emission Tomography

Abstract

Purpose. The aim of this study is to synthesize and evaluate68Ga-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 of68Ga(DOTA-LRB) in athymic nude mice bearing MDA-MB-231 and MCF-7 human breast cancer xenografts. Additionally, the evaluations of18F-fluorodeoxyglucose (FDG), as a glucose metabolism radiotracer for imaging tumors in the same xenografts, have been conducted as a comparison.Results. The radiochemical purity of68Ga(DOTA-LRB) was >95%. MicroPET dynamic imaging revealed that the uptake of68Ga(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 of68Ga(DOTA-LRB). The tumor uptake values of18F-FDG were3.79±0.57and1.93±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.