Head and Neck PET/CT: Therapy Response Interpretation Criteria (Hopkins Criteria)—Interreader Reliability, Accuracy, and Survival Outcomes

Head and neck cancers have an incidence of 550,000 cases annually worldwide (1). Most head and neck cancers are squamous cell in origin. Well-known risk factors associated with head and neck cancers are tobacco use, alcohol consumption, and human papillomavirus (HPV) infection (2). The incidence of HPV-associated head and neck squamous cell carcinoma (HNSCC) is increasing, and these tumors most commonly arise from the oropharynx (3). Surgery, radiotherapy, or concurrent chemoradiation therapy are accepted standard treatment options in patients with HNSCC. Despite advances in therapeutic techniques, there is a high incidence of locoregional disease recurrence (15%–50%) and a 9% incidence of distant metastases. Early identification of recurrence and assessment of therapy response would highly benefit patients and potentially improve survival (4,5). PET combined with CT using 18F-FDG is useful in the evaluation of HNSCC, in diagnosis, staging, therapy assessment, and follow-up (6–12). Studies have shown that pretreatment 18F-FDG PET/CT is useful in accurate staging and prediction of disease recurrence and survival (13). Similarly, multiple studies have shown that posttreatment 18F-FDG PET/CT is useful in evaluating treatment response, detecting recurrence (14), and predicting outcomes and survival (15,16). Despite the value of PET/CT in therapy assessment, no established qualitative interpretation criteria for head and neck PET/CT have been published. The objective of this study was to validate interpretation criteria for therapy assessment (Hopkins Criteria) for head and neck PET/CT and establish its accuracy, reader reliability, and the predictive value for survival outcome in patients with HNSCC.