BACKGROUND: [(18)F]HX4 is a promising new PET tracer developed to identify hypoxic areas in tumor tissue. This study analyzes [(18)F]HX4 kinetics and assesses the performance of simplified methods for quantification of [(18)F]HX4 uptake. To this end, eight patients with non-small cell lung cancer received dynamic PET scans at three different time points (0, 120, and 240 min) after injection of 426 ± 72 MBq [(18)F]HX4, each lasting 30 min. Several compartment models were fitted to time activity curves (TAC) derived from various areas within tumor tissue using image-derived input functions.
RESULTS: Best fits were obtained using the reversible two-tissue compartment model with blood volume parameter (2T4k+VB). Simplified measures correlated well with VT estimates (tumor-to-blood ratio (TBr) R (2) = 0.96, tumor-to-muscle ratio R (2) = 0.94, standardized uptake value R (2) = 0.89).
CONCLUSIONS: [(18)F]HX4 shows reversible kinetics in tumor tissue: 2T4k+VB. TBr based on static imaging at 2 or 4 h can be used for quantification of [(18)F]HX4 uptake.