title: Qualitative interpretation of PET scans using a Likert scale to assess neck node response to radiotherapy in head and neck cancer.
abstract: OBJECTIVE
  The aim of this study was to determine whether PET scans after radiotherapy (RT), visually interpreted as equivocal regarding metabolic neck node response can be used to accurately categorize patients as responders or nonresponders using a Likert scale and/or maximum standardized uptake value (SUVmax). Other aims were to determine the performance of different methods for assessing post-RT PET scans (visual inspection, a Likert scale and SUVmax) and to establish whether any method is superior in predicting regional control (RC) and overall survival (OS).
  
  
  METHODS
  In 105 patients with neck node-positive head and neck cancer, the neck node response was evaluated by FDG PET/CT 6 weeks after RT. The scans were clinically assessed by visual inspection and, for the purposes of this analysis, re-evaluated using the Deauville criteria, a five-point Likert scale previously used in lymphoma studies. In addition, SUVmax was determined.
  
  
  RESULTS
  All assessment methods were able to significantly predict RC but not OS. The methods were also able to significantly predict remission of tumour after completion of RT. Of the 105 PET scans, 19 were judged as equivocal on visual inspection. The Likert scale was preferable to SUVmax for grouping patients as responders or nonresponders.
  
  
  CONCLUSIONS
  All methods (visual inspection, SUVmax and the Likert scale) identified responders and nonresponders and predicted RC. A Likert scale is a promising tool to reduce to a minimum the problem of PET scans judged as equivocal. Consensus regarding qualitative assessment would facilitate PET reporting in clinical practice.
authors.affiliation: Department of Otorhinolaryngology (ORL)-Head and Neck Surgery, Skane University Hospital, Lund University, 22185, Lund, Sweden. johanna.sjovall@med.lu.se.
authors.forename: Johanna
authors.identifier: http://orcid.org/0000-0001-6540-7168
authors.initials: J
authors.lastname: Sjövall
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Skane University Hospital, Lund University, Lund, Sweden.
authors.forename: Ulrika
authors.initials: U
authors.lastname: Bitzén
authors.affiliation: Department of Oncology and Radiation Physics, Skane University Hospital, Lund University, Lund, Sweden.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Kjellén
authors.affiliation: Department of Oncology and Radiation Physics, Skane University Hospital, Lund University, Lund, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Nilsson
authors.affiliation: Department of Otorhinolaryngology (ORL)-Head and Neck Surgery, Skane University Hospital, Lund University, 22185, Lund, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Wahlberg
authors.affiliation: Department of Oncology and Radiation Physics, Skane University Hospital, Lund University, Lund, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Brun
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D005260:Female; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography / Q000379:methods* / Q000592:standards
keywords: Head and neck cancer; Patient outcome assessment; Positron emission tomography; Qualitative evaluation; Radiotherapy; Therapy assessment