title: Multiparametric analysis of bone marrow in cancer patients using simultaneous PET/MR imaging: Correlation of fat fraction, diffusivity, metabolic activity, and anthropometric data.
abstract: BACKGROUND
  To analyze the regional composition of bone marrow (BM) in correlation with metabolic activity and diffusivity using simultaneous positron emission tomography (PET)/MRI.
  
  
  METHODS
  Retrospective analysis of 18F-FDG-PET/MR scans of 110 patients was performed. A three-dimensional gradient-echo sequence with Dixon-based fat-water separation was used for fat quantification. Dixon images, diffusion-weighted images (DWI) and 18F-FDG-PET were co-registered. Mean values of fat fraction (FF), standardized uptake value (SUV), and apparent diffusion coefficient (ADC) of BM were measured in different anatomical regions. Correlation of FF, SUV, and ADC and association of BM fat content and metabolic activity with anthropometric data was analyzed (Pearson). BM fat content and metabolic activity was compared in patients with and without chemotherapy (t-test).
  
  
  RESULTS
  Regional differences in BM were found with highest fat content (93 ± 8%) and lowest ADC (0.22 ± 0.18 × 10(-3) mm(2) /s) in the peripheral skeleton and highest SUV in the spine (1.77 ± 0.6). There was a significant inverse correlation between FF and SUV (r = -0.73; P < 0.0001) and a significant inverse correlation between FF and ADC (r = -0.62; P < 0.0001). In patients with chemotherapy, a tendency to higher fat content and lower metabolic activity was observed in the proximal skeleton, although no statistical significance was reached.
  
  
  CONCLUSIONS
  BM shows distinct regional variations in FF, SUV, and ADC. The inverse correlation of FF and SUV in BM suggests that BM adipose tissue does not have a comparable high metabolic activity as brown adipose tissue.
authors: Diagnostic and Interventional Radiology, University Department of Radiology, University Hospital Tuebingen, Tuebingen, Germany.
authors: Christina
authors: C
authors: Schraml
authors: Diagnostic and Interventional Radiology, University Department of Radiology, University Hospital Tuebingen, Tuebingen, Germany.
authors: Marinus
authors: M
authors: Schmid
authors: Diagnostic and Interventional Radiology, University Department of Radiology, University Hospital Tuebingen, Tuebingen, Germany.
authors: Sergios
authors: S
authors: Gatidis
authors: Diagnostic and Interventional Radiology, University Department of Radiology, University Hospital Tuebingen, Tuebingen, Germany.
authors: Holger
authors: H
authors: Schmidt
authors: Nuclear Medicine, University Department of Radiology, University Hospital Tuebingen, Tuebingen, Germany.
authors: Christian
authors: C
authors: la Fougère
authors: Diagnostic and Interventional Radiology, University Department of Radiology, University Hospital Tuebingen, Tuebingen, Germany.
authors: Konstantin
authors: K
authors: Nikolaou
authors: Diagnostic and Interventional Radiology, University Department of Radiology, University Hospital Tuebingen, Tuebingen, Germany.
authors: Nina F
authors: NF
authors: Schwenzer
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism* / Q000473:pathology; D050154:Adiposity; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000886:Anthropometry / Q000379:methods; D001835:Body Weight; D001853:Bone Marrow / Q000378:metabolism* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media / Q000493:pharmacokinetics; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003287:Contrast Media; D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG; PET/MRI; adipose tissue; bone marrow; diffusion-weighted imaging; fat quantification