Posttreatment assessment of response using FDG-PET/CT for patients treated with definitive radiation therapy for head and neck cancers

Int J Radiat Oncol Biol Phys. 2006 Aug 1;65(5):1315-22. doi: 10.1016/j.ijrobp.2006.03.015. Epub 2006 Jun 5.


Purpose: The goal of this study was to evaluate coregistered [18F] fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) for the detection of persistent disease after definitive radiation therapy in head and neck cancer.

Methods and materials: Posttreatment FDG-PET/CT was performed in 28 patients on average 8 weeks (range, 4 to 15.7 weeks) after completing definitive radiation therapy. FDG-PET/CT was visually analyzed for the entire patient group and at two time points (4-8 and >8 weeks) after treatment. The contrast-enhanced CT portion of PET/CT was separately analyzed blinded to the results of coregistered FDG-PET/CT and classified as negative or positive for residual locoregional disease. Pathologic findings and clinical follow-up served as the reference standard.

Results: Follow-up data were available for all 28 patients (median, 17.6 months). Regarding the detection of residual disease, the overall sensitivity and specificity of FDG-PET/CT was 76.9% and 93.3%, respectively, compared with 92.3% and 46.7% for contrast-enhanced CT. The accuracy of FDG-PET/CT was 85.7%, compared with 67.9% for CT alone. All false-negative (n = 3) and false-positive (n = 1) FDG-PET/CT results occurred between 4 and 8 weeks after treatment. At 8 weeks or later after treatment, the specificity of CT was 28%, compared with 100% for FDG-PET/CT.

Conclusions: The metabolic-anatomic information from coregistered FDG-PET/CT provided the most accurate assessment for treatment response when performed later than 8 weeks after the conclusion of radiation therapy. FDG-PET/CT excelled by a higher specificity and overall diagnostic performance than CT imaging alone. These results support a potential clinical role of FDG-PET/CT in the early assessment of therapy response after definitive radiation therapy.

Publication types

  • Evaluation Study

MeSH terms

  • Adult
  • Aged
  • Carcinoma, Squamous Cell / diagnostic imaging
  • Carcinoma, Squamous Cell / radiotherapy
  • False Negative Reactions
  • False Positive Reactions
  • Female
  • Fluorodeoxyglucose F18*
  • Head and Neck Neoplasms / diagnostic imaging*
  • Head and Neck Neoplasms / radiotherapy
  • Humans
  • Male
  • Middle Aged
  • Neoplasm, Residual / diagnostic imaging
  • Positron-Emission Tomography / methods*
  • Radiopharmaceuticals*
  • Sensitivity and Specificity
  • Tomography, X-Ray Computed / methods*


  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18