title: Determination of accuracy and precision of lesion uptake measurements in human subjects with time-of-flight PET.
abstract: Inclusion of time-of-flight (TOF) information in PET reconstructions has been demonstrated to improve image quality through better signal-to-noise ratios, faster convergence, better lesion detectability, and better image uniformity. The goal of this work was to assess the impact of TOF information on the accuracy and precision of quantitative measurements of activity uptake in small lesions in clinical studies.
  
  
  METHODS
  Data from small (10-mm diameter) spheres were merged with list-mode data from 6 healthy volunteers after injection of (18)F-FDG. Six spheres having known activity uptake with respect to the average whole-body uptake were embedded in both the liver and the lung of the subject's data. Images were reconstructed with TOF information and without TOF information (non-TOF reconstruction). The measured uptake was compared with the known activity; variability was measured across 60 bootstrapped replicates of the merged data, across the 6 spheres within a given organ, and across all spheres in all subjects.
  
  
  RESULTS
  The average uptake across all spheres and subjects was approximately 50% higher in the lung and 20% higher in the liver with TOF reconstruction than with non-TOF reconstruction at comparable noise levels. The variabilities across replicates, across spheres within an organ, and across all spheres and subjects were 20%-30% lower with TOF reconstruction than with non-TOF reconstruction in the lung; in the liver, the variabilities were 10%-20% lower with TOF reconstruction than with non-TOF reconstruction.
  
  
  CONCLUSIONS
  TOF reconstruction leads to more accurate and precise measurements, both within a subject and across subjects, of the activity in small lesions under clinical conditions.
authors.affiliation: Department of Radiology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and.
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Daube-Witherspoon
authors.forename: Suleman
authors.initials: S
authors.lastname: Surti
authors.forename: Amy E
authors.initials: AE
authors.lastname: Perkins
authors.forename: Joel S
authors.initials: JS
authors.lastname: Karp
mesh_terms: D000328:Adult; D000465:Algorithms; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008099:Liver / Q000000981:diagnostic imaging; D008168:Lung / Q000000981:diagnostic imaging; D008297:Male; D008863:Microspheres; D049268:Positron-Emission Tomography / Q000379:methods* / Q000592:standards; D019275:Radiopharmaceuticals / Q000008:administration & dosage*; D015203:Reproducibility of Results; D014915:Whole-Body Counting; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: PET; instrumentation; positron emission tomography; research methods; time-of-flight PET