18F-FDG PET for retropharyngeal lymph node metastasis in oropharyngeal and hypopharyngeal cancers: impact on diagnosis and prediction analysis - Chan, S C; Lin, C Y; Ng, S H; Chang, J T; Wang, H M; Liao, C T; Lo, C W; Yen, T C (Nucl Med Commun, 2010)