Compare the post-treatment neck with the first post-treatment baseline (about 12 weeks after therapy): expected changes are symmetric and non-mass-like; a new or enlarging enhancing mass, or focal FDG uptake, is scored by NI-RADS and acted on.
Orient first
- NI-RADS 1–4 for the primary site and the neck, each with a management recommendation (verify the version).
- Post-radiotherapy changes: mucosal and fat stranding, retropharyngeal oedema, laryngeal oedema — symmetric.
- Flap reconstructions have their own expected appearance: fat and denervated muscle.
Acquire the study
- Contrast-enhanced CT neck with ≤ 2 mm slices, soft tissue and bone windows.
The manoeuvre
- Primary site: diffuse non-mass-like enhancement (expected) vs discrete nodular enhancing mass (suspicious).
- Compare with the baseline at the same site: new or enlarging in mm.
- Neck nodes: size, necrosis, extranodal extension.
- Complications: osteoradionecrosis in bone window, fistula, carotid blowout signs.
What confirms it
- A NI-RADS 3–4 finding confirmed on biopsy.
What licenses you to exclude it
- Stable non-mass-like changes and no focal uptake (NI-RADS 1) make recurrence unlikely.
The classic misread
- Scoring expected symmetric post-radiotherapy oedema as recurrence.
- Reading without the baseline study.