Study On The Optimal Imaging Time And Imaging Mechanism Of Near-Infrared Fluorescence Imaging For Prostate Cancer Xenografts

Objective:To investigate the dynamic characteristics,optimal development time and imaging mechanism of Indocyanine green(ICG)in vitro near infrared fluorescence imaging of subcutaneous xenograft tumor of prostate cancer in nude mice.Methods:10 SPF BALB/c-nu male nude mice aged 3-4 weeks,weighing 15-18 g,were selected and fed in a standard environment.Human prostate cancer cell line PC3 tumor-bearing nude mouse models were constructed.The nude mice of 1-7 were injected with ICG solution of 10mg/kg via tail vein.Near infrared fluorescence imaging was performed at 1min,30 min,1h,2h,4h,8h,12 h,24h,48 h and 72 h after injection,respectively.Nude mice of 8-10 were injected with 10 mg/kg ICG in the same way.After 24 hours,tumor tissues,liver,stomach,small intestine,large intestine,kidney and paraneoplastic adipose tissue were dissected for near-infrared fluorescence imaging.Tumor tissues were taken for pathological section,and the distribution of ICG in tumor tissues was observed under a fluorescence microscope.Results:The fluorescence intensity at the tumor site of 1-7 nude mice injected with ICG gradually increased with time,and the background fluorescence around the tumor gradually decreased.After 12 h,the TBR was the best,and the tumor development effect was the best,which lasted up to 24 h.The average gray value of each organ of 8-10 nude mice was taken as follows: stomach > large intestine > small intestine > liver > tumor > kidney > peritumoral fat tissue,indicating that ICG can be excreted through the gastrointestinal tract.Under the fluorescence microscope,the tumor tissue showed obvious green fluorescence,which confirmed that the ICG dye was concentrated in the tumor tissue.Conclusion:After intravenous ICG injection,ICG can be concentrated in subcutaneous prostate cancer xenografts through high permeability and retention effect,and the imaging effect is the best at 12-24 hours after injection.This study provides a new theoretical basis for accurate tumor resection in prostate cancer patients using near infrared fluorescence imaging.