Power and Interpretation of Positron Emission Tomography and Magnetic Resonance Imaging of Prostate Cancer in Nude Mouse

The changes in signal intensity of micro-PET and micro-MRI images of tumors were characterized using histology, »flow cytometry, DNA fragmentation analysis and NMR peaks. This approach was used to assay the chemotherapeutic efficacy based on FDG and intracellular(IC) sodium changes in tumor. A detailed methodology is presented for PC-3 tumor progression. The logic is presented for signal intensities as a result of ion and metabolite changes during tumor cell apoptosis. PC-3 cell lines were compared with DU-145, LNCaP cell lines in culture for the [Na]i and [Ca]i ion sensing dyes, cell death, NMR peaks and apoptosis staining for chemotherapeutic action of different drugs. As a model experiment, PC3 cell lines were injected to propagate prostate tumors in nude mouse. After PC3 tumor imaging, Taxotere VP-16 Etoposide was administered in vivo and imaging was done after 12 hours and 24 hours. Tumors were taken out for immunohistological staining. The micro-PET and micro-MRI images showed increased 18-FDG uptake and sodium signal intensities in tumor. Taxotere induced an increase in IC-Na signal. FDG uptake increased with decreased tumor size. Histological features were analyzed for high tumor risk and decreased tumor viability. Different cell lines showed characteristic fluorescent dye response by different drugs. Sodium NMR method isolated intracellular sodium. Necrosis and fluid were darker on IC-Na images and hyperactive on PET images. Apoptosis rich regions showed characteristic nuclei with S phase DNA histogram, appearing brighter on ICNa images and mild active on PET images. NMR spectra showed characteristic high phosphocholine peaks. Therefore, the integrated sodium MRI and PET imaging approach offers an in vivo drug monitoring method. The histoimmunological staining of prostate tumor was specific to apoptosis and the NMR peaks were tumor specific. Infor Med Slov: 2007; 12(1): 1-14 Sharma R et al.: Power and Interpretation of PET and MRI of Prostate Cancer in Nude Mouse 2