Result: The mean tumor volumes on 18F-FDG PET / CT and CT were 26.1 ± 15.2 cm3 and 27.5 ± 15.2 cm3 (p<0.05), the median lymph node volumes on 18F-FDG PET / CT and CT were 4.2 cm3 and 1.5 cm3 (p<0.05), respectively.