title: Correcting tumour SUV for enhanced bone marrow uptake: retrospective 18F-FDG PET/CT studies.
abstract: OBJECTIVE
  The concentration of F-FDG in the bone marrow is usually low. One common cause of high uptake is due to bone marrow stimulating drugs administered in conjunction with chemotherapy or radiation therapy. It has been hypothesized that the sequestration of F-FDG to the bone marrow may reduce the standardized uptake value (SUV) of a tumour. We tested this hypothesis by quantifying total F-FDG uptake in the bone marrow of patients with visibly enhanced bone marrow uptake and computing its effect on tumour SUV.
  
  
  METHODS
  Total F-FDG in bone marrow was measured in two groups of PET/CT studies: one (n=19) with visibly enhanced bone marrow, the other (n=5), a baseline group with 'normal' levels of uptake. To measure the F-FDG in bone marrow, the entire skeleton in the CT was segmented from surrounding tissue, and the resulting volume applied to the PET image. Using kinetic analysis we show that the predicted correction factor to tumour SUV is given by (1-q0/Q)/(1-q/Q), where Q is the injected dose, and q and q0 are enhanced and baseline bone marrow uptake (MBq).
  
  
  RESULTS
  The enhanced bone marrow uptake averaged 8.9+/-3.2% of injected dose (15.2% max) vs. 4.2+/-0.4% (4.6% max) at baseline. This resulted in a predicted artificial decrease in tumour SUV of up to 11.5% (4.9+/-4.3%, on average).
  
  
  CONCLUSIONS
  Enhanced bone marrow uptake is predicted to reduce tumour SUVs by as much as 11.5% in our patient group and is a potential confounding factor in using SUV for monitoring tumour response to therapy.
authors.affiliation: Department of Radiology, University of California, San Francisco, USA. teobk@stanford.edu
authors.forename: Boon-Keng
authors.initials: BK
authors.lastname: Teo
authors.forename: Shiva
authors.initials: S
authors.lastname: Badiee
authors.forename: Mohiuddin
authors.initials: M
authors.lastname: Hadi
authors.forename: Tuwin
authors.initials: T
authors.lastname: Lam
authors.forename: Lauran
authors.initials: L
authors.lastname: Johnson
authors.forename: Youngho
authors.initials: Y
authors.lastname: Seo
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Bacharach
authors.forename: Bruce H
authors.initials: BH
authors.lastname: Hasegawa
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Franc
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001853:Bone Marrow / Q000000981:diagnostic imaging* / Q000378:metabolism*; D019046:Bone Marrow Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18