Characterization And Feasibility Study Of A Near Infrared CCD Imager For Monitoring Tumor Hemodynamics

Prostate cancer is one of the most common types of cancers diagnosed among North American men. Chemotherapy is generally used to target advanced metastatic prostate cancer. Near infrared spectroscopy (NIRS) has been previously investigated to monitor the hemodynamic changes in rat prostate tumors; however, the previous study with NIRS is limited by its spatial resolution. The goal of this study is to characterize an NIR, CCD imager and to explore the feasibility of using the CCD imager to non-invasively monitor hemodynamic changes in rat prostate tumors during gas intervention. Firstly, studies were conducted to characterize the CCD imager and understand the propagation of photons through simulated tissue phantoms. These results aid our understanding of light propagation through a uniform medium and detection of photons by the NIR, CCD imager. Secondly, experiments were performed to study the feasibility of the imager to monitor hemodynamic changes in rat prostate tumors during gas intervention. Adult male Copenhagen rats implanted with prostate carcinoma on the fore back were used in this study. Cyclophosphamide, a chemotherapeutic agent, was administered to treat the rat prostate tumors, and pure oxygen was used as gas intervention to introduce hemodynamic perturbation in the tumors during the measurements. After the CCD images were taken at multiple NIR wavelengths, for comparison with the previous records, the images were processed and integrated to provide global temporal files of various hemodynamic parameters for three different groups of rats. A few topographic hemodynamic maps were also obtained, showing spatial heterogeneity within the tumors. The animal experimental results also support the efficacy of cyclophosphamide to be effective in inhibiting the growth of prostate carcinoma. Furthermore, the animal data reveals possible experimental sources causing instability of the measured NIR signals. Overall, this initial study basically demonstrates the feasibility of using a multi-wavelength NIR CCD imager for non-invasively monitoring tumor regional hemodynamics.