title: Diagnostic value of retrospective PET-MRI fusion in head-and-neck cancer.
abstract: BACKGROUND
  To assess the diagnostic value of retrospective PET-MRI fusion and to compare the results with side-by-side analysis and single modality use of PET and of MRI alone for locoregional tumour and nodal staging of head-and-neck cancer.
  
  
  METHODS
  Thirty-three patients with head-and-neck cancer underwent preoperative contrast-enhanced MRI and PET/CT for staging. The diagnostic data of MRI, PET, side-by-side analysis of MRI and PET images and retrospective PET-MRI fusion were systematically analysed for tumour and lymph node staging using receiver operating characteristic (ROC) analysis. The results were correlated to the histopathological evaluation.
  
  
  RESULTS
  The overall sensitivity/specificity for tumour staging for MRI, PET, side-by-side analysis and retrospective PET-MRI fusion was 79%/66%, 82%/100%, 86%/100% and 89%/100%, respectively. The overall sensitivity/specificity for nodal staging on a patient basis for MRI, PET, side-by-side analysis and PET-MRI fusion was 94%/64%, 94%/91%, 94%/82% and 94%/82%, respectively. MRI, PET, side-by-side analysis and retrospective image fusion were associated with correct diagnosis/over-staging/under-staging of N-staging in 70.4%/18.5%/11.1%, 81.5%/7.4%/11.1%, 81.5%/11.1%/7.4% and 81.5%/11.1%/7.4%, respectively.ROC analysis showed no significant differences in tumor detection between the investigated methods. The Area Under the Curve (AUC) for MRI, PET, side-by-side analysis and retrospective PET-MRI fusion were 0.667/0.667/0.702/0.708 (p > 0.05). The most reliable technique in detection of cervical lymph node metastases was PET imaging (AUC: 0.95), followed by side-by-side analysis and retrospective image fusion technique (AUC: 0.941), which however, was not significantly better then the MRI (AUC 0.935; p > 0.05).
  
  
  CONCLUSIONS
  We found a beneficial use of multimodal imaging, compared with MRI or PET imaging alone, particular in individual cases of recurrent tumour disease. Side-by-side analysis and retrospective image fusion analysis did not perform significantly differently.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Technische Universität München, Ismaningerstr, 22, D-82675 München, Germany. loeffelbein@mkg.med.tum.de.
authors.forename: Denys J
authors.initials: DJ
authors.lastname: Loeffelbein
authors.forename: Michael
authors.initials: M
authors.lastname: Souvatzoglou
authors.forename: Veronika
authors.initials: V
authors.lastname: Wankerl
authors.forename: Julia
authors.initials: J
authors.lastname: Dinges
authors.forename: Lucas M
authors.initials: LM
authors.lastname: Ritschl
authors.forename: Thomas
authors.initials: T
authors.lastname: Mücke
authors.forename: Anja
authors.initials: A
authors.lastname: Pickhard
authors.forename: Matthias
authors.initials: M
authors.lastname: Eiber
authors.forename: Markus
authors.initials: M
authors.lastname: Schwaiger
authors.forename: Ambros J
authors.initials: AJ
authors.lastname: Beer
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D019788:Fluorodeoxyglucose F18; D006258:Head and Neck Neoplasms / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D019788:Fluorodeoxyglucose F18