Initial Performance of NI-RADS to Predict Residual or Recurrent Head and Neck Squamous Cell Carcinoma

ROC curve for NI-RADS at the lymph nodes with AUC = 0.71 (95% CI, 0.597–0.826).

ROC curve for NI-RADS for primary site and lymph nodes combined, with AUC = 0.756 (95% CI, 0.682–0.8).

NI-RADS primary site category 2a: superficial mucosal abnormality. Primary T4a N2c base of tongue squamous cell carcinoma, status post chemoradiotherapy. A, CECT showed only subtle/questionable asymmetric enhancement in the right vallecula (arrow) retrospectively after review of PET. B, Fused PET image shows asymmetric uptake in the right vallecula (arrow). Direct visualization did show ulcerated mucosa, but the biopsy was negative for tumor. Clinically, this was deemed a radiation-related injury.

NI-RADS primary site category 2a: superficial mucosal abnormality. Primary T2 larynx squamous cell carcinoma status post chemoradiotherapy. A, CECT showed subtle irregularity of the anterior commissure and anterior true vocal cords bilaterally (arrow). B, Corresponding fused PET image shows focal mucosal uptake (arrow). After direct visualization revealed suspicious mucosal findings, the biopsy showed persistent disease. Although this lesion does demonstrate focal avid FDG uptake, it is in a special category of mucosal abnormality. In the published NI-RADS 1.0 by Aiken et al,⁵ these are scored as 2a because the linked management recommendation is direct visualization.

NI-RADS primary site category 2b: ill-defined asymmetric soft tissue. T4N0 oral cavity squamous cell carcinoma. CECT shows asymmetric full soft tissue around fibular reconstruction of the mandible (arrow). The linked management recommendation is shorter interval surveillance. Repeat CECT at 3 months showed no interval change (not shown). Subsequent clinical follow-up also demonstrated improvement and no disease recurrence.

NI-RADS primary site category 3: discrete enhancing lesion. T4a larynx squamous cell carcinoma, status post total laryngectomy, bilateral neck dissection, and chemoradiotherapy. A, CECT shows a 1-cm discrete rounded hyperenhancing nodule along the lateral border of neopharynx, deep to the flap (arrow). B, Fused PET images show focal high FDG uptake (arrow). This was given a category 3 score, and endoscopic biopsy demonstrated recurrence.