title: Whole-body nonenhanced PET/MR versus PET/CT in the staging and restaging of cancers: preliminary observations.
abstract: OBJECTIVE
  To assess the diagnostic performance of whole-body non-contrast material-enhanced positron emission tomography (PET)/magnetic resonance (MR) imaging and PET/computed tomography (CT) for staging and restaging of cancers and provide guidance for modality and sequence selection.
  
  
  METHODS
  This study was approved by the institutional review board and national government authorities. One hundred six consecutive patients (median age, 68 years; 46 female and 60 male patients) referred for staging or restaging of oncologic malignancies underwent whole-body imaging with a sequential trimodality PET/CT/MR system. The MR protocol included short inversion time inversion-recovery ( STIR short inversion time inversion-recovery ), Dixon-type liver accelerated volume acquisition ( LAVA liver accelerated volume acquisition ; GE Healthcare, Waukesha, Wis), and respiratory-gated periodically rotated overlapping parallel lines with enhanced reconstruction ( PROPELLER periodically rotated overlapping parallel lines with enhanced reconstruction ; GE Healthcare) sequences. Primary tumors (n = 43), local lymph node metastases (n = 74), and distant metastases (n = 66) were evaluated for conspicuity (scored 0-4), artifacts (scored 0-2), and reader confidence on PET/CT and PET/MR images. Subanalysis for lung lesions (n = 46) was also performed. Relevant incidental findings with both modalities were compared. Interreader agreement was analyzed with intraclass correlation coefficients and κ statistics. Lesion conspicuity, image artifacts, and incidental findings were analyzed with nonparametric tests.
  
  
  RESULTS
  Primary tumors were less conspicuous on STIR short inversion time inversion-recovery (3.08, P = .016) and LAVA liver accelerated volume acquisition (2.64, P = .002) images than on CT images (3.49), while findings with the PROPELLER periodically rotated overlapping parallel lines with enhanced reconstruction sequence (3.70, P = .436) were comparable to those at CT. In distant metastases, the PROPELLER periodically rotated overlapping parallel lines with enhanced reconstruction sequence (3.84) yielded better results than CT (2.88, P < .001). Subanalysis for lung lesions yielded similar results (primary lung tumors: CT, 3.71; STIR short inversion time inversion-recovery , 3.32 [P = .014]; LAVA liver accelerated volume acquisition , 2.52 [P = .002]; PROPELLER periodically rotated overlapping parallel lines with enhanced reconstruction , 3.64 [P = .546]). Readers classified lesions more confidently with PET/MR than PET/CT. However, PET/CT showed more incidental findings than PET/MR (P = .039), especially in the lung (P < .001). MR images had more artifacts than CT images.
  
  
  CONCLUSIONS
  PET/MR performs comparably to PET/CT in whole-body oncology and neoplastic lung disease, with the use of appropriate sequences. Further studies are needed to define regionalized PET/MR protocols with sequences tailored to specific tumor entities.
authors.affiliation: From the Department of Medical Radiology, Divisions of Nuclear Medicine (M.W.H., P.A., F.P.K., L.H., C.M.P., I.A.B., M.P., G.D., G.K.v.S., P.V.H.), Diagnostic and Interventional Radiology (P.A., F.P.K., P.V.H.), and Neuroradiology (M.W.H., F.P.K.), University Hospital Zurich, Rämistrasse 100, 8091 Zurich, Switzerland; and GE Healthcare, Waukesha, Wis (G.D.).
authors.forename: Martin W
authors.initials: MW
authors.lastname: Huellner
authors.forename: Philippe
authors.initials: P
authors.lastname: Appenzeller
authors.forename: Félix P
authors.initials: FP
authors.lastname: Kuhn
authors.forename: Lars
authors.initials: L
authors.lastname: Husmann
authors.forename: Carsten M
authors.initials: CM
authors.lastname: Pietsch
authors.forename: Irene A
authors.initials: IA
authors.lastname: Burger
authors.forename: Miguel
authors.initials: M
authors.lastname: Porto
authors.forename: Gaspar
authors.initials: G
authors.lastname: Delso
authors.forename: Gustav K
authors.initials: GK
authors.lastname: von Schulthess
authors.forename: Patrick
authors.initials: P
authors.lastname: Veit-Haibach
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D003287:Contrast Media; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009367:Neoplasm Staging; D009369:Neoplasms / Q000473:pathology*; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed; D051598:Whole Body Imaging
chemical_list: D003287:Contrast Media