title: Diagnostic accuracy of sequential co-registered PET+MR in comparison to PET/CT in local thoracic staging of malignant pleural mesothelioma.
abstract: OBJECTIVE
  To investigate the diagnostic accuracy of sequential co-registered PET+MR (PET+MR) for local staging of malignant pleural mesothelioma (MPM) compared to PET/CT.
  
  
  METHODS
  In a prospective clinical trial 34 consecutive patients (median age 66 years; range 40-79 years; 1 female, 33 male) with known MPM, who underwent PET/CT and PET+MR exams for either staging or re-staging/follow-up were evaluated. Imaging was conducted using a tri-modality PET/CT-MR set-up (Discovery PET/CT 690, 3T Discovery MR 750w, both GE Healthcare, Waukesha, WI, USA). In 26 cases histopathology served as standard of reference. Two independent readers evaluated images for T and N stage, confidence level (sure to unsure; 1-3) and subjective overall image quality (very good to non-diagnostic; 1-4). Inter-observer agreement of T and N stages (Cohen's kappa) and interclass correlation coefficient (ICC) between PET/CT vs. PET+MR was calculated.
  
  
  RESULTS
  Inter observer agreement for evaluation of T and N Stage in PET/CT images was excellent (k=0.844 and k=0.824, respectively), whereas PET+MR imaging showed substantial agreement in T and N stage (k=0.729 and k=0.691, respectively). The ICC of PET/CT vs. PET+MR for evaluation of both, T and N Stage, was excellent (ICC=0.951 and ICC=0.93, respectively). Diagnostic confidence was scored significantly higher in PET+MR compared to PET/CT (mean score=1.66 and 1.93, respectively; p=0.004). Image quality was diagnostic for all image series. Comparing pT and pN stage vs cT and cN stage (n=26 cases), both imaging modalities showed excellent agreement for T stage (ICCPET+MR=0.888 vs. ICCPET/CT=0.853, respectively) and substantial to moderate agreement for N stage (ICCPET+MR=0.683 vs. ICC=0.595PET/CT, respectively).
  
  
  CONCLUSIONS
  Our findings suggest that diagnostic accuracy of PET+MR is comparable to PET/CT for local staging of MPM, whereas radiologists felt significantly more confident staging PET+MR compared to PET/CT images (p=0003), using dedicated sequences.
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Switzerland. Electronic address: Katharina.Martini@usz.ch.
authors.forename: Katharina
authors.initials: K
authors.lastname: Martini
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Switzerland. Electronic address: Andreas.Meier@usz.ch.
authors.forename: Andreas
authors.initials: A
authors.lastname: Meier
authors.affiliation: Division of Thoracic Surgery, University Hospital Zurich,University of Zurich, Switzerland. Electronic address: Isabelle.Schmitt-Opitz@usz.ch.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Opitz
authors.affiliation: Division of Thoracic Surgery, University Hospital Zurich,University of Zurich, Switzerland. Electronic address: Walter.Weder@usz.ch.
authors.forename: Walter
authors.initials: W
authors.lastname: Weder
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Switzerland; Clinic of Nuclear Medicine, University Hospital Zurich,University of Zurich, Switzerland. Electronic address: Patrick.Veit-Haibach@usz.ch.
authors.forename: Patrick
authors.initials: P
authors.lastname: Veit-Haibach
authors.affiliation: Department of Oncology, University Hospital Zurich,University of Zurich, Switzerland. Electronic address: Rolf.Stahel@usz.ch.
authors.forename: Rolf A
authors.initials: RA
authors.lastname: Stahel
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Switzerland. Electronic address: Thomas.Frauenfelder@usz.ch.
authors.forename: Thomas
authors.initials: T
authors.lastname: Frauenfelder
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008175:Lung Neoplasms / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008297:Male; D008654:Mesothelioma / Q000175:diagnosis*; D000086002:Mesothelioma, Malignant; D008875:Middle Aged; D064847:Multimodal Imaging; D009367:Neoplasm Staging; D010997:Pleural Neoplasms / Q000175:diagnosis*; D000072078:Positron Emission Tomography Computed Tomography; D049268:Positron-Emission Tomography; D015203:Reproducibility of Results
keywords: Diagnostic confidence; Malignant pleural mesothelioma; PET/CT; PET/MR; TN staging