Conclusion
In the visual assessment of suspected relapse, interobserver agreement between observers decreases with subjective insecurity. Although additional knowledge of the initial staging PET and radiotherapy delineation volumes improves the sensitivity (0.85 vs 0.92) of the qualitative evaluation slightly, it has no significant impact on the specificity (0.86 vs 0.89). The implementation of a patient individual threshold value definition for the SULpeak as previously discussed by Wahl et al