Multiparametric Imaging of Tumor Hypoxia and Perfusion with 18 F-Fluoromisonidazole Dynamic PET in Head and Neck Cancer.

Tumor hypoxia and perfusion are independent prognostic indicators of patient outcome. We developed the methodology for and investigated the utility of multiparametric imaging of tumor hypoxia and perfusion with ¹⁸ F-fluoromisonidazole ( ¹⁸ F-FMISO) dynamic PET (dPET) in head and neck cancer. Methods: One hundred twenty head and neck cancer patients underwent 0- to 30-min ¹⁸ F-FMISO dPET in a customized immobilization mask, followed by 10-min static acquisitions starting at 93 ± 6 and 160 ± 13 min after injection. A total of 248 lesions (≥2 cm ³ ) were analyzed. Voxelwise pharmacokinetic modeling was conducted using an irreversible 1-plasma 2-tissue-compartment model to calculate surrogate biomarkers of tumor hypoxia ( k ₃ ), perfusion ( K ₁ ), and ¹⁸ F-FMISO distribution volume. The analysis was repeated with truncated dPET datasets. Results: Substantial inter- and intratumor heterogeneity was observed for all investigated metrics. Equilibration between the blood and unbound ¹⁸ F-FMISO was rapid in all tumors. ¹⁸ F-FMISO distribution volume deviated from the expected value of unity, causing discrepancy between k ₃ maps and total ¹⁸ F-FMISO uptake and reducing the dynamic range of total ¹⁸ F-FMISO uptake for quantifying the degree of hypoxia. Both positive and negative trends between hypoxia and perfusion were observed in individual lesions. All investigated metrics were reproducible when calculated from a truncated 20-min dataset. Conclusion: ¹⁸ F-FMISO dPET provides the data necessary to generate parametric maps of tumor hypoxia, perfusion, and radiotracer distribution volume. These data clarify the ambiguity in interpreting ¹⁸ F-FMISO uptake and improve the characterization of lesions. We show total acquisition times can be reduced to 20 min, facilitating the translation of ¹⁸ F-FMISO dPET into the clinic.
(© 2017 by the Society of Nuclear Medicine and Molecular Imaging.)