title: PET/MRI for the evaluation of patients with lymphoma: initial observations.
abstract: OBJECTIVE
  The objective of our study was to assess the role of recently introduced hybrid PET/MRI in the evaluation of lymphoma patients using PET/CT as a reference standard.
  
  
  METHODS
  In this prospective study 28 consecutive lymphoma patients (18 men, 10 women; mean age, 53.6 years) undergoing clinically indicated PET/ CT were subsequently imaged with PET/MRI using residual FDG activity from the PET/ CT study. Blinded readers evaluated PET/CT (reference standard), PET/MRI, and diffusion-weighted imaging (DWI) studies separately; for each study, they assessed nodal and extranodal involvement. Each FDG-avid nodal station was marked and compared on DWI, PET/MRI, and PET/CT. Modified Ann Arbor staging was performed and compared between PET/MRI and PET/CT. The maximum standardized uptake value (SUVmax) on PET/MRI for FDG-avid nodal lesions was compared with the SUVmax on PET/CT. The apparent diffusion coefficient (ADC) for FDG-avid nodal lesions was compared to SUVmax on PET/MRI.
  
  
  RESULTS
  Fifty-one FDG-avid nodal groups were identified on PET/CT in 13 patients. PET/MRI identified 51 of these nodal groups with a sensitivity of 100%. DWI identified 32 nodal groups for a sensitivity of 62.7%. PET/MRI staging and PET/CT staging were concordant in 96.4% of patients. For the one patient with discordant staging results, disease was correctly upstaged to stage IV on the basis of the PET/MRI finding of bone marrow involvement, which was missed on PET/CT. DWI staging was concordant with PET/CT staging in 64.3% of the patients. The increased staging accuracy of PET/MRI relative to DWI was significant (p=0.004). SUVmax measured on PET/MRI and PET/CT showed excellent statistically significant correlation (r=0.98, p<0.001). There was a poor negative correlation between ADC and SUVmax (r=-0.036, p=0.847).
  
  
  CONCLUSIONS
  PET/MRI can be used to assess disease burden in lymphoma with sensitivity similar to PET/CT and can be a viable alternative for lymphoma staging and follow-up.
authors: 1 Department of Radiology, New York University Langone Medical Center, 660 First Ave, New York, NY 10016.
authors: Laura
authors: L
authors: Heacock
authors: Joseph
authors: J
authors: Weissbrot
authors: Roy
authors: R
authors: Raad
authors: Naomi
authors: N
authors: Campbell
authors: Kent P
authors: KP
authors: Friedman
authors: Fabio
authors: F
authors: Ponzo
authors: Hersh
authors: H
authors: Chandarana
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008223:Lymphoma / Q000175:diagnosis* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: PET/MRI; diffusion-weighted imaging (DWI); hybrid; lymphoma