title: Whole-body diffusion-weighted MRI and (18)F-FDG PET/CT can discriminate between different lymphoma subtypes.
abstract: OBJECTIVE
  To determine whether combined 2-[(18)F]-fluoro-2-deoxy-d-glucose ((18)F-FDG) positron-emission tomography (PET)/computed tomography (CT) and diffusion-weighted imaging (DWI) can be used for characterisation of different lymphoma subtypes, i.e., indolent versus aggressive lymphoma, and also to assess the prognostic value of different quantitative parameters of whole-body (WB) DWI and (18)F-FDG PET/CT.
  
  
  METHODS
  Pre-therapeutic WB magnetic resonance imaging (MRI) including DWI and (18)F-FDG PET/CT were performed in lymphoma patients. Different quantitative DWI and (18)F-FDG PET/CT parameters were evaluated for characterisation of different lymphoma subtypes. These parameters were also correlated, both separately and in combination, against overall survival (OS) and progression-free survival (PFS). A lesion-by-lesion analysis was performed for correlation analysis between maximum standardised uptake value (SUVmax), mean standardised uptake value (SUVmean) and mean apparent diffusion coefficient (ADC).
  
  
  RESULTS
  Fifty patients were included in the study and divided into three groups: Hodgkin's lymphoma (HL), n=12; aggressive non-Hodgkin's lymphoma (NHL), n=29 (including 20 patients with diffuse large B-cell lymphoma, DLBCL); and indolent NHL, n=9. Indolent NHL showed significantly lower mean ADC values than the other two lymphoma groups (p=0.013). Aggressive NHL had a higher SUVmax than HL. The OS analysis of all patients showed a relationship (p=0.006) between increased mean ADC and longer OS. A model with both SUVmean and mean ADC, strengthened the possibility to predict PFS; however, a separate analysis of the DLBCL patients showed that none of the quantitative parameters could predict OS or PFS.
  
  
  CONCLUSIONS
  ADC can discriminate between indolent and aggressive NHL. This finding can be useful in assessing possible transformation from indolent to aggressive NHL. ADC, ADC/SUV, and SUV cannot predict OS/PFS independent of lymphoma subtype.
authors.affiliation: Section of Radiology, Department of Radiology, Oncology and Radiation Science, Uppsala University Hospital, Uppsala, Sweden. Electronic address: firas.mosavi@akademiska.se.
authors.forename: F
authors.initials: F
authors.lastname: Mosavi
authors.affiliation: Section of Nuclear Medicine, Department of Radiology, Oncology and Radiation Science, Uppsala University Hospital, Uppsala, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Wassberg
authors.affiliation: StatSoft Scandinavia AB, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Selling
authors.affiliation: Section of Oncology, Department of Radiology, Oncology and Radiation Science, Uppsala University Hospital, Uppsala, Sweden.
authors.forename: D
authors.initials: D
authors.lastname: Molin
authors.affiliation: Section of Radiology, Department of Radiology, Oncology and Radiation Science, Uppsala University Hospital, Uppsala, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Ahlström
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods / Q000592:standards; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods / Q000592:standards; D049268:Positron-Emission Tomography / Q000379:methods / Q000592:standards; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000592:standards; D051598:Whole Body Imaging / Q000379:methods / Q000592:standards; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18