Non-invasive visualization of tumors in the mouse liver using a novel nanoparticle contrast enhanced micro-CT imaging procedure / 中国实验动物学报

ABSTRACT

Objective To establish an in vivo imaging method of normal or tumorous liver in mice by using a new type nanoparticle contrast agent, ExiTron nano 12000, coupled with micro-CT imaging.Methods Six 6-8-week old male C57BL/6J mice were randomly divided into group A and group group B, by intravenous injection of 50μL and 100μL Ex-iTron nano 12000, respectively.In vivo Micro-CT scans were performed before contrast agent injection, 3 minutes, 24 hours, 7, 14, 28 and 56 days after injection.To determine which dose is suitable for long-term studies, gray scale value a-nalysis was performed on selected region of interest ( ROI) in the left lobe and right anterior lobe of the liver, and the chan-ges of liver tissue contrast was monitored after ExiTron nano 12000 injection.Three male HBV transgenic mice bearing liver tumors ( group C) were intravenously injected with the determined dose of ExiTron nano 12000 and were monitored by mi-cro-CT scans as above described.At 56 days after ExiTron nano 12000 injection, the mice were sacrificed and liver sam-ples were taken for histological analysis.Results Cross-sectional images taken at various time points and the average gray scale value ( AGSV) analysis in the mouse liver revealed that the AGSV peaked at 24 hours after injection of contrast rea-gent and good contrast still presented in the livers within 56 days of observation for both groups, though group B showed a significantly higher contrast than group A (P＜0.01).Those data indicated that the dose of group B (100μL) was better to maintain ExiTron nano 12000 in the liver of mice for a long time.Contrast-enhanced by 100μL of ExiTron nano 12000, the liver tumor nodules in the mice of group C could be clearly delineated by Micro CT imaging during a 56 days observa-tion.Histological analysis revealed atypical hyperplasia, enlarged nuclei with hyperchromasia and cell necrosis in the tumors.Conclusions An in vivo imaging method was established to non-invasively visualize mouse liver using micro-CT combined with nanoparticle-based contrast agent and this technology may be applied to a live imaging of murine primary liv-er tumors.