Figure 13b. Metastatic squamous cell carcinoma in a 45-year-old woman. After biopsy of a right cervical lymph node revealed the carcinoma, FDG PET-CT was performed to search for the primary tumor. (a) Axial CT image obtained at the level of the oropharynx shows mild tonsillar asymmetry without a definite mass. (b) Corresponding fused FDG PET-CT image shows intense hypermetabolism in the left tonsil (arrow), which was the site of the primary tumor.