PET-CT for Salivary Gland — and Sinus Tumours

Both scans are usually needed and they answer different questions. MRI is often done first or alongside PET-CT for salivary gland tumours because it shows local extent and the relationship to structures such as the facial nerve. PET-CT then adds the whole-body picture — whether cancer has reached lymph nodes or distant sites. The order depends on clinical urgency and local availability, and your team will explain which is most pressing to obtain first.

No. PET-CT can show whether a lump is metabolically active and whether there are other areas of concern in the body. It cannot tell your team whether the lump is benign or malignant, or which type of tumour it is. Only biopsy or surgical removal with pathological examination answers that question. A bright PET result does not confirm cancer, and a faint result does not rule it out — particularly for low-grade salivary gland tumours.

Radiotherapy causes inflammation in treated tissue that appears active on PET in a way that resembles tumour. Scanning too soon risks the report reflecting inflammation rather than disease activity, which can lead to unnecessary further investigations or delayed reassurance. The appropriate waiting period depends on the treatment received. Your team will advise on timing for your case, following NCCN and ESMO guidance for post-treatment response assessment in head and neck cancers.

A PET-CT showing no distant spread is positive information — it suggests the disease appears localised at the time of scanning. It does not guarantee the outcome of treatment, which depends on the tumour type, stage, response to treatment, and factors specific to your situation. For adenoid cystic carcinoma, late recurrence is a recognised possibility even after an apparently successful initial treatment and clear scans. Your oncologist can explain what the staging result means for your individual prognosis.

Perineural spread means cancer has travelled along a nerve sheath rather than as a discrete mass. It is associated with adenoid cystic carcinoma and changes surgical planning considerably, because the surgeon needs to know how far along the nerve the disease may have extended. PET-CT does not reliably detect it. If you have adenoid cystic carcinoma, ask your team whether perineural involvement was assessed on MRI with contrast, and what the finding was. It is a reasonable and important question.

PET-CT at CION is coordinated through partner imaging centres. Your CION oncologist will arrange the referral and ensure the imaging centre has the clinical context needed for an accurate report. Results return to your CION team and are reviewed alongside your biopsy result, MRI, and examination findings before any decision is made. Ask at your next appointment which partner centre will do the scan, what preparation is needed on the day, and when the report is expected.