Comprehensive Review of Post-treatment Imaging in Head and Neck Cancers: From expected to unexpected and beyond.

Abstract

Head and neck cancer management requires multidisciplinary approach in which radical surgery with or without flap reconstructions and neck dissection, along with radiotherapy (RT)/chemoradiotherapy (CRT) serve as the key components. Neoadjuvant chemotherapy (NACT) and immunotherapy are used in selected cases based on the institutional preference. Knowledge of expected posttreatment changes on imaging is essential to differentiate it from recurrence. In addition, awareness of various posttreatment complications is imperative for their early detection on imaging. Distorted anatomy after treatment poses diagnostic challenge, hence, proper choice of imaging modality and appropriate timing of scan is pertinent for accurate posttreatment evaluation. In this article, we have provided a comprehensive review on expected imaging appearances post RT/CRT and after major types of head and neck squamous cell carcinoma (HNSCC) surgeries. In addition, we have extensively reviewed the imaging appearances of various posttreatment complications, and recurrences at the primary and lymph nodal sites. We have also delved into the patterns of recurrence in human papillomavirus (HPV) positive HNSCC in this article. Furthermore, we have provided flowcharts and discussed recommendations on the site-specific and treatment related imaging modalities to be used along with their appropriate timing, for adequate evaluation of HNSCC after treatment. We have also reviewed posttreatment reporting of imaging findings using Neck Imaging Reporting and Data Systems (NIRADS) and Hopkins criteria. In addition, we have also touched upon the role of advanced imaging techniques for posttreatment HNSCC evaluation.