title: PET/MRI and PET/CT in follow-up of head and neck cancer patients.
abstract: OBJECTIVE
  Positron emission tomography (PET)/MRI combines the functional ability of PET and the high soft tissue contrast of MRI. The aim of this study was to assess contrast-enhanced (ce)PET/MRI compared to cePET/CT in patients with suspected recurrence of head and neck cancer (HNC).
  
  
  METHODS
  Eighty-seven patients underwent sequential cePET/CT and cePET/MRI using a trimodality PET/CT-MRI set-up. Diagnostic accuracy for the detection of recurrent HNC was evaluated using cePET/CT and cePET/MRI. Furthermore, image quality, presence of unclear (18)F-fluorodeoxy-D-glucose (FDG) findings of uncertain significance and the diagnostic advantages of use of gadolinium contrast enhancement were analysed.
  
  
  RESULTS
  cePET/MRI showed no statistically significant difference in diagnostic accuracy compared to cePET/CT (91.5 vs 90.6%). Artefacts' grade was similar in both methods, but their location was different. cePET/CT artefacts were primarily located in the suprahyoid area, while on cePET/MRI, artefacts were more equally distributed among the supra and infrahyoid neck regions. cePET/MRI and cePET/CT showed 34 unclear FDG findings; of those 11 could be solved by cePET/MRI and 5 by cePET/CT. The use of gadolinium in PET/MRI did not yield higher diagnostic accuracy, but helped to better define tumour margins in 6.9% of patients.
  
  
  CONCLUSIONS
  Our data suggest that cePET/MRI may be superior compared to cePET/CT to specify unclear FDG uptake related to possible tumour recurrence in follow-up of patients after HNC. It seems to be the modality of choice for the evaluation of the oropharynx and the oral cavity because of a higher incidence of artefacts in cePET/CT in this area mainly due to dental implants. However, overall there is no statistically significant difference.
authors.affiliation: Department of Medical Radiology, Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland, marcelo.araujoqueiroz@usz.ch.
authors.forename: Marcelo A
authors.initials: MA
authors.lastname: Queiroz
authors.forename: Martin
authors.initials: M
authors.lastname: Hüllner
authors.forename: Felix
authors.initials: F
authors.lastname: Kuhn
authors.forename: Gerhardt
authors.initials: G
authors.lastname: Huber
authors.forename: Christian
authors.initials: C
authors.lastname: Meerwein
authors.forename: Spyros
authors.initials: S
authors.lastname: Kollias
authors.forename: Gustav
authors.initials: G
authors.lastname: von Schulthess
authors.forename: Patrick
authors.initials: P
authors.lastname: Veit-Haibach
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000175:diagnosis / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18