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WE‐C‐303A‐03: Pharmacokinetic Analysis of Hypoxia 18‐Fluoromisonidazole Dynamic PET Imaging in Head and Neck Cancer

Purpose: This paper uses pharmacokinetic analysis of 18‐Fluoromisonidazole (FMISO) dynamic PETimaging to investigate if there is any correlation between tumor hypoxia (Ki ), tumor‐to‐blood ratio (T/B) in late‐time image, local blood perfusion (k1 ), and local vasculature fraction (β) for head‐and‐neck cancer patients. Methods and Materials: Newly diagnosed patients with head‐and‐neck cancer prior to chemotherapy or radiotherapy underwent dynamic FMISO‐PET scan. The data was acquired in 3 consecutive PET/CT dynamic scan segments, with start acquisition time [0, 1, 2, 3, 4, 5, 10, 15, 20, 25, 90, 95, 180, 185] minutes, consisting of 5 frames in 1‐minute frames, following by 5‐minutes frames. The dynamic PETimages were first registered with each other and then analyzed using Philips Resarch's Voxulus pharmacokinetic software. The (Ki, k1 , β) kinetic parameter images were derived for each patient. Results: Nine head‐and‐neck cancer patients' data were analyzed. Representative images of FDG‐PET (showing the tumor),CT (showing the anatomy), late‐time FMISO‐PET (showing T/B), and (Ki, k1 , β) kinetic parameter images were shown consisting of a patient example with good concordance of tumor hypoxia and high T/B, one with concordance of no tumor hypoxia and low T/B, and one with ambiguity between tumor hypoxia and T/B. Scatter diagrams were plotted between each pair of T/B, Ki, k1 , β and corresponding correlation coefficient computed. Conclusions: There is strong positive correlation between ROI's T/B and hypoxia index Ki . However, due to the statistical photon counting noise in PETimaging, and the amplification of noise in kinetic analysis, the direct correlation between individual pixel's T/B and hypoxia is not obvious. For a tumor ROI, there is slight negative correlation between k1 and Ki , moderate positive correlation between β and Ki , but no correlation between β and Ki . This work is supported in part by NIH PO1 CA115675.