Fig 1.

NI-RADS 3 true-positive. A 62-year-old man with advanced HPV-positive oropharyngeal squamous cell carcinoma. A, Pretreatment PET/CT shows 2 areas of FDG-avid infiltrative tumor in the oropharynx, one centered in the right faucial tonsil with invasion of the adjacent right tongue base and right-sided floor of mouth and one centered in the left tongue base. B, Surveillance PET/CT obtained at 3.5 months after completion of treatment shows interval improvement and a decrease in the size of the primary tumor, but there remains a substantial amount of residual FDG avidity in the right-sided floor of the mouth (white arrow), which is suspicious for residual viable tumor. Treatment failure was subsequently confirmed with biopsy.