title: A Large Cohort Study of 18F Fluoro-Deoxy-Glucose Uptake in Normal Spinal Cord: Quantitative Assessment of the Contamination From Adjacent Vertebral Marrow Uptake and Validity of Normalizing the Cord Uptake Against the Lumbar Thecal Sac.
abstract: OBJECTIVE
  This study aimed (1) to assess the influence of age, sex, blood glucose, and body mass index on the F fluoro-deoxy-glucose (F-FDG) uptake in normal spinal cord; (2) to quantitatively evaluate contamination of the spinal cord SUVmax by the adjacent vertebral marrow activity; and (3) to investigate the validity of normalizing spinal cord SUVmax against lumbar thecal sac SUVmax.
  
  
  METHODS
  Two hundred positron emission tomography-computed tomography examinations of subjects with normal spinal cord were retrospectively reviewed. SUVmax of spinal cord and vertebral body was obtained at C2, C5, T6, T12, and L3 levels. Pearson correlation coefficients (r) were obtained at each level between spinal cord SUVmax and vertebral marrow SUVmax, age, body mass index, and blood glucose. Cord to background ratio (CTB) was calculated as the ratio between SUVmax of spinal cord and SUVmax of L3 thecal sac. The coefficient of variation (CV) of spinal cord SUVmax was compared with the CV of CTB.
  
  
  RESULTS
  Spinal cord SUVmax was highest at C2 (mean, 1.76) and lowest at T6 (mean, 1.37) with SD of 0.32 to 0.36 SUV. Sex (P > 0.45), age (r: -0.25 to -0.06), body mass index (r: 0.19 to 0.27), and blood glucose (r: -0.17 to 0.22) had no impact on the spinal cord SUVmax. A moderate to strong positive correlation (r: 0.66-0.80) was found between spinal cord SUVmax and the corresponding vertebral marrow SUVmax. The CV of CTB was greater (0.28-0.32) than the CV of spinal cord SUVmax (0.19-0.25) across all levels.
  
  
  CONCLUSIONS
  Of the variables studied, only contamination from adjacent vertebral marrow activity significantly affected the SUVmax of spinal cord. This contamination should be corrected for when reporting spinal cord FDG uptake. Lumbar thecal sac is not a valid reference for normalizing spinal cord FDG uptake.
authors: From the Department of Radiology, Mayo Clinic, Jacksonville, FL.
authors: Neema J
authors: NJ
authors: Patel
authors: Vivek
authors: V
authors: Gupta
authors: Prasanna G
authors: PG
authors: Vibhute
authors: Manoj K
authors: MK
authors: Jain
authors: Joseph M
authors: JM
authors: Accurso
mesh_terms: D017677:Age Distribution; D000375:Aging / Q000378:metabolism; D001853:Bone Marrow / Q000000981:diagnostic imaging / Q000378:metabolism*; D015331:Cohort Studies; D004388:Dura Mater / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D005431:Florida / Q000453:epidemiology; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017678:Sex Distribution; D013116:Spinal Cord / Q000000981:diagnostic imaging* / Q000378:metabolism*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18