title: Dynamic PET-CT studies for characterizing nasopharyngeal carcinoma metabolism:  comparison of analytical methods.
abstract: OBJECTIVE
  To investigate the optimal PET protocol and analytical method to characterize the glucose metabolism in nasopharyngeal carcinoma (NPC).
  
  
  METHODS
  Newly diagnosed NPC patients were recruited and a dynamic PET-CT scan was performed. The optimized threshold to derive the arterial input function (AIF) was studied. Two-tissue compartmental kinetic modeling using three, four, and five parameters, Patlak graphical analysis, and time sensitivity (S-factor) analysis were performed. The best compartmental model was determined in terms of goodness of fit, and correlated with Ki from Patlak graphical analysis and the S-factor. The methods with R>0.9 and P<0.05 were considered acceptable. The protocols using two static scans with its retention index (RI=(SUV(2)/SUV(1)-1)×100%, where SUV is the standardized uptake value) were also studied and compared with S-factor analysis.
  
  
  RESULTS
  The best threshold of 0.6 was determined and used to derive AIF. The kinetic model with five parameters yields the best statistical results, but the model with k4=0 was used as the gold standard. All Ki values and some S-factors from data between various intervals (10-30, 10-45, 15-30, 15-45, 20-30, and 20-45 min) fulfilled the criteria. The RIs calculated from the S-factor were highly correlated to RI derived from simple two-point static scans at 10 and 30 min (R=0.9, P<0.0001).
  
  
  CONCLUSIONS
  The Patlak graphical analyses and even a 20-min-interval S-factor analysis or simple two-point static scans were shown to be sufficient to characterize NPC metabolism, confirming the clinical feasibility of applying a short dynamic with image-derived AIF or simple two-point static PET scans for studying NPC.
authors: Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong.
authors: Bingsheng
authors: B
authors: Huang
authors: Pek-Lan
authors: PL
authors: Khong
authors: Dora Lai-Wan
authors: DL
authors: Kwong
authors: Bortau
authors: B
authors: Hung
authors: Chun-Sing
authors: CS
authors: Wong
authors: Ching-Yee Oliver
authors: CY
authors: Wong
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D001786:Blood Glucose / Q000378:metabolism; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism*; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D001786:Blood Glucose; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18