Fig. 4.
True positive evaluation with combined PET/DWIMRI (positive concordant findings on MRI, DWI and PET). A 48-year-old male with reflex otalgia 1 year after radiochemotherapy for squamous cell carcinoma of the base of the tongue. Endoscopy: oedema and intact mucosa. T2 (A): infiltrative tumour recurrence with intermediate signal (arrows) in the left tongue base, extrinsic tongue muscles, vallecula and parapharyngeal space. Suspected invasion of the left submandibular gland (pink asterisk). Submucosal oedema with very high T2 signal (green asterisk). Normal right submandibular gland (blue asterisk). ADC map (B): restricted diffusion suggesting recurrence (white asterisk, ADCmean = 1.127 × 10-3 mm2/s). High ADC signal surrounding the tumour (green asterisks, ADCmean = 1.789–1.965 × 10-3 mm2/s) due to oedema. Left and right submandibular glands (pink and blue asterisks). (C) PET/MRI (PET fused with T1) suggests recurrence (increased FDG uptake, arrows, SUVmean = 7.688; SUVmax = 12.11). (D) Whole-organ axial section from surgical specimen (same orientation) confirms recurrence (white asterisk) invading the above-described structures. Submandibular gland (pink asterisk). Tumour margins contoured by pathologist (white line). Green asterisks: inflammatory oedema. T-stage on PET/DWIMRI was T4a. Pathological stage was pT4a