Best Imaging Time of Near-infrared Fluorescence Imaging for Prostate Cancer Xenografts

Abstract

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 We selected 10 male SPF BALB/c-nu nude mice to construct PC3 tumor-bearing nude mouse models of human prostate cancer cell line. Seven nude mice were injected with 10mg/kg ICG via tail vein. Near-infrared fluorescence imaging was performed at different time after injection to observe the dynamic characteristics of the transplanted tumor and whole body fluorescence images, and the tumor-to-background ratio (TBR) was calculated. Another three nude mice were injected with 10mg/kg ICG in the same way. After 24h, tumor tissues, different viscera and paraneoplastic adipose tissues 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 fluorescence microscope. Results The fluorescence intensity at the tumor site of 7 nude mice injected with ICG gradually increased with time, and the background fluorescence around the tumor gradually decreased. After 12h, TBR was the best. The average gray value of each organ of three nude mice was as follows: stomach > large intestine > small intestine > liver > tumor > kidney > peritumoral fat tissue. Under the fluorescence microscope, the tumor tissues showed obvious green fluorescence. Conclusion After intravenous ICG injection, ICG could be concentrated in subcutaneous prostate cancer xenografts through high permeability and retention effect, and the imaging effect is the best in 12-24 hours.

Keywords

• prostate cancer
• indocyanine green
• near-infrared fluorescence imaging
• imaging time