DETECTION OF CANCER RECURRENCE IN IRRADIATED MANDIBLE USING POSITRON EMISSION TOMOGRAPHY

Positron emission tomography (PET) is a promising method for pretherap eutic assessment of spread of squamous cell carcinomas (SCC) in the he ad and neck. A 41-year-old man with a history of operated and irradiat ed SCC of the tongue presented 4 years later with symptoms and signs o f mandibular osteoradionecrosis. No changes related to malignancy coul d be seen in panoramic radiographs or computed tomography scanning wit h contrast enhancement. Since a biopsy of the involved region was posi tive for SCC, a PET study with [F-18]fluorodeoxyglucose (FDG) was perf ormed. In dynamic PET images, intensive uptake of FDG was seen in a sm all area close to the right mental foramen. A hemi-mandibulectomy with reconstruction using a free vascularized graft from iliac crest was p erformed. In the resected specimen, histological examination showed a 1.2-mm focus of SCC in the soft tissue and bone around the mental fora men. These findings indicate that FDG-PET might be useful for presurgi cal evaluation of cancer recurrence in a previously irradiated mandibl e, especially if PET can accurately differentiate viable tumor tissue from radiation-induced fibrosis and inflammation.