Objective: The Neck Imaging Reporting and Data System (NI-RADS) is a standardized numerical reporting template for surveillance of head and neck squamous cell carcinoma (HNSCC). Our aim was to analyze the accuracy of NI-RADS on the first posttreatment fluorodeoxyglucose positron emission tomography/contrast-enhanced computed tomography (PET/CECT).
Study design: Retrospective cohort study.
Setting: Academic tertiary hospital.
Subject and methods: Patients with HNSCC with a 12-week posttreatment PET/CECT interpreted using the NI-RADS template and 9 months of clinical and radiologic follow-up starting from treatment completion between June 2014 and July 2016 were included. Treatment failure was defined as positive tumor confirmed by biopsy or Response Evaluation Criteria in Solid Tumors criteria. Cox proportional hazards models were performed.
Results: This study comprised 199 patients followed for a median of 15.5 months after treatment completion (25% quartile, 11.8 months; 75% quartile, 20.2 months). The rates of treatment failure increased with each incremental increase in NI-RADS category from 1 to 3 (4.3%, 9.1%, and 42.1%, respectively). A Cox proportional hazards model demonstrated a strong association between NI-RADS categories and treatment failure at both primary and neck sites (hazard ratio [HR], 2.60 and 5.22, respectively; P < .001). In the smaller treatment subgroup analysis, increasing NI-RADS category at the primary site in surgically treated patients and treatment failure did not achieve statistically significant association (HR, 0.88; P = .82).
Conclusion: Increasing NI-RADS category at the baseline posttreatment PET/CECT is strongly associated with increased risk of treatment failure in patients with HNSCC.
Keywords: PET; radiology; squamous cell carcinoma.