title: Diagnostic performance of FDG-PET/MRI and WB-DW-MRI in the evaluation of lymphoma: a prospective comparison to standard FDG-PET/CT.
abstract: BACKGROUND
  Use of FDG-PET/CT for staging and restaging of lymphoma patients is widely incorporated into current practice guidelines. Our aim was to prospectively evaluate the diagnostic performance of FDG-PET/MRI and WB-DW-MRI compared with FDG-FDG-PET/CT using a tri-modality PET/CT-MRI system.
  
  
  METHODS
  From 04/12 to 01/14, a total of 82 FDG-PET/CT examinations including an additional scientific MRI on a tri-modality setup were performed in 61 patients. FDG-PET/CT, FDG-PET/MRI, and WB-DW-MRI were independently analyzed. A lesion with a mean ADC below a threshold of 1.2 × 10(-3) mm(2)/s was defined as positive for restricted diffusion. FDG-PET/CT and FDG-PET/MRI were evaluated for the detection of lesions corresponding to lymphoma manifestations according to the German Hodgkin Study Group. Imaging findings were validated by biopsy (n = 21), by follow-up imaging comprising CT, FDG-PET/CT, and/or FDG-PET/MRI (n = 32), or clinically (n = 25) (mean follow-up: 9.1 months).
  
  
  RESULTS
  FDG-PET/MRI and FDG-PET/CT accurately detected 188 lesions in 27 patients. Another 54 examinations in 35 patients were negative. WB-DW-MRI detected 524 lesions, of which 125 (66.5% of the aforementioned 188 lesions) were true positive. Among the 188 lesions positive for lymphoma, FDG-PET/MRI detected all 170 instances of nodal disease and also all 18 extranodal lymphoma manifestations; by comparison, WB-DW-MRI characterized 115 (67.6%) and 10 (55.6%) lesions as positive for nodal and extranodal disease, respectively. FDG-PET/MRI was superior to WB-DW-MRI in detecting lymphoma manifestations in patients included for staging (113 vs. 73), for restaging (75 vs. 52), for evaluation of high- (127 vs. 81) and low-grade lymphomas (61 vs. 46), and for definition of Ann Arbor stage (WB-DW-MRI resulted in upstaging in 60 cases, including 45 patients free of disease, and downstaging in 4).
  
  
  CONCLUSIONS
  Our results indicate that FDG-PET/CT and FDG-PET/MRI probably have a similar performance in the clinical work-up of lymphomas. The performance of WB-DW-MRI was generally inferior to that of both FDG-PET-based methods but the technique might be used in specific scenarios, e.g., in low-grade lymphomas and during surveillance.
authors.affiliation: Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland. Herrmann_K1@ukw.de.|Department of Nuclear Medicine, Universitätsklinikum Würzburg, Oberdürrbacher Str. 6, DE-97080, Würzburg, Germany. Herrmann_K1@ukw.de.
authors.forename: Ken
authors.initials: K
authors.lastname: Herrmann
authors.affiliation: Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland. marcelo.araujoqueiroz@gmail.com.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Queiroz
authors.affiliation: Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland. martin.huellner@usz.ch.|Department of Neuroradiology, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland. martin.huellner@usz.ch.|University of Zurich, Zurich, Switzerland. martin.huellner@usz.ch.
authors.forename: Martin W
authors.initials: MW
authors.lastname: Huellner
authors.affiliation: Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland. felipegaliza@gmail.com.
authors.forename: Felipe
authors.initials: F
authors.lastname: de Galiza Barbosa
authors.affiliation: Department of Nuclear Medicine, Universitätsklinikum Würzburg, Oberdürrbacher Str. 6, DE-97080, Würzburg, Germany. Buck_A@ukw.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Buck
authors.affiliation: Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland. niklaus.schaefer@usz.ch.|Department of Medical Oncology, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland. niklaus.schaefer@usz.ch.|University of Zurich, Zurich, Switzerland. niklaus.schaefer@usz.ch.
authors.forename: Niklaus
authors.initials: N
authors.lastname: Schaefer
authors.affiliation: Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland. paul.stolzmann@usz.ch.|Department of Neuroradiology, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland. paul.stolzmann@usz.ch.|University of Zurich, Zurich, Switzerland. paul.stolzmann@usz.ch.
authors.forename: Paul
authors.initials: P
authors.lastname: Stolzman
authors.affiliation: Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland. Patrick.Veit-Haibach@usz.ch.|Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland. Patrick.Veit-Haibach@usz.ch.|University of Zurich, Zurich, Switzerland. Patrick.Veit-Haibach@usz.ch.
authors.forename: Patrick
authors.initials: P
authors.lastname: Veit-Haibach
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003955:Diagnostic Tests, Routine / Q000379:methods*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008223:Lymphoma / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D051598:Whole Body Imaging / Q000379:methods*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18