title: A bone marrow F-18 FDG uptake exceeding the liver uptake may indicate bone marrow hyperactivity.
abstract: OBJECTIVE
  In clinical positron emission tomography (PET) studies for oncology, it is occasionally required to differentiate a diffuse increase in bone marrow (BM) F-18 fluoro-2-deoxyglucose (FDG) uptake due to the involvement of malignancy or hematopoietic disease and that due to the administration of hematopoietic cytokines, an inflammation reaction, or stimulation by some types of malignancy. The objectives of this study were to clarify the relationships between BM F-18 FDG uptake and blood parameters as well as age, and also to determine the degree of F-18 FDG accumulation that constitutes an abnormal level referring to blood parameters.
  
  
  METHODS
  Records of 65 patients, 32 with benign diseases and 33 with malignancies without metastasis in bone and liver until a half year after the PET examination, were analyzed retrospectively. Regions of interest were placed on the liver and the lower thoracic and lumbar vertebrae to measure the standardized uptake value (SUV), and vertebral SUVs were averaged as the BM SUV(mean). The BM SUV(mean) was divided by the liver SUV to calculate the BM/liver ratio. The relationships among the BM SUV(mean), or BM/liver ratio, and blood parameters and age were tested using multiple regression analysis.
  
  
  RESULTS
  In both patients with and without malignancy, a multiple regression model using the BM/liver ratio showed a higher coefficient of determination value than that using the BM SUV(mean), indicating that the correction by the liver SUV reduced the interindividual variation in the BM SUV(mean). The BM/liver ratio was negatively correlated with age (beta = -0.41 and -0.43, respectively) and positively correlated with serum C-reactive protein (CRP) level (beta = 0.39 and 0.46, respectively) in both groups of patients. Every patient with benign disease who had a ratio greater than or equal to 1 had an increased CRP level.
  
  
  CONCLUSIONS
  The BM F-18 FDG uptake depends on the patient's age and serum CRP level, both with and without malignancy. A BM F-18 FDG uptake greater than or equal to that of the liver may indicate BM activation.
authors.affiliation: Department of Nuclear Medicine and Radiology, Institute of Development, Aging, and Cancer, Tohoku University, Sendai 980-8575, Japan. kenta@idac.tohoku.ac.jp
authors.forename: Kentaro
authors.initials: K
authors.lastname: Inoue
authors.forename: Ryoi
authors.initials: R
authors.lastname: Goto
authors.forename: Ken
authors.initials: K
authors.lastname: Okada
authors.forename: Shigeo
authors.initials: S
authors.lastname: Kinomura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Fukuda
mesh_terms: D000367:Age Factors; D001853:Bone Marrow / Q000378:metabolism* / Q000503:physiopathology*; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006405:Hematology; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008875:Middle Aged; D009369:Neoplasms / Q000097:blood / Q000378:metabolism; D012044:Regression Analysis; D012189:Retrospective Studies
chemical_list: D019788:Fluorodeoxyglucose F18