PT - JOURNAL ARTICLE AU - Bartlett, Rachel AU - Zanzonico, Pat AU - Carlin, Sean AU - Chen, Qing AU - Roble, Gordon AU - O'Donoghue, Joseph AU - Beattie, Bradley AU - Narayanan, Manoj AU - Georgi, Jens-Christoph AU - Humm, John TI - Kinetic modeling of [<sup>18</sup>F]-FMISO microPET data and its correlation with image-guided pO<sub>2</sub> measurements DP - 2010 May 01 TA - Journal of Nuclear Medicine PG - 232--232 VI - 51 IP - supplement 2 4099 - http://jnm.snmjournals.org/content/51/supplement_2/232.short 4100 - http://jnm.snmjournals.org/content/51/supplement_2/232.full SO - J Nucl Med2010 May 01; 51 AB - 232 Objectives Hypoxia increases resistance to treatment and may predict tumor progression. Non-invasive methods to determine intra-tumor hypoxia, such as PET, are being explored and validated against direct methods such as partial oxygen pressure (pO2) probe measurements and immunohistochemistry. The current study validates 18F-fluoromisonidazole ([18F]-FMISO) PET imaging in the assessment of tumor hypoxia by demonstrating the expected correlation between microPET-derived [18F]-FMISO kinetic parameters in rat tumors with spatially registered pO2 measurements. Methods Sixteen Dunning R3327-AT prostate tumor-bearing nude rats were immobilized in a custom-fabricated whole-body mold, injected iv with FMISO, and imaged for 105 minutes on a Focus 120 microPET. Maintaining anesthesia, animals were then transferred in situ to our robotic system for image-guided intra-tumoral pO2 measurements (Oxylite probe). A removable registration plate with 4 fiduciary markers was used to align the robot and microPET coordinate systems. Results A voxel-based 2-tissue compartment model of the microPET-derived FMISO kinetics in tumor yielded a significant inverse correlation between pO2 and the hypoxia-dependent FMISO “trapping” parameter (k3). Specifically, scatter plots exhibited a sigmoidal relationship between the pO2 vales and the corresponding FMISO k3, flux and Patlak (Ki) parameters with correlation coefficients (mean + SD) of 0.72 ± 0.29, 0.75 ± 0.28, and 0.80 ± 0.25, respectively. Conclusions Image-guided pO2 probe and measurements validated FMISO PET imaging of tumor hypoxia, but also illustrated statistical and resolution limitations in the correlation between pO2 values and FMISO uptake parameters