title: Improvement in clinical evaluation of PET/CT images with high resolution algorithms.
abstract: OBJECTIVE
  Positron emission tomography/computed tomography (PET/CT) diagnosis relies on quality of the reconstructed images which strongly depends on the algorithms used. The aim of this work was to assess if the introduction of high resolution algorithms allows a better identification of reduced diameter lesions, leading to improved diagnosis in clinical setting.
  
  
  METHODS
  The performances of a Siemens Biograph6 True Point PET/CT used for this work were checked for both standard and high resolution algorithms. Clinical studies of thirteen patients referred for PET/CT were selected and grouped according to the metabolic tumor volume and their position in the FOV and then reconstructed with both algorithms; clinical studies were estimated in terms of geometric characteristics and uptake values (SUVmax, SUVmean) of the lesions.
  
  
  RESULTS
  FWHM, spatial resolution, contrast ratio and image quality of the PET/CT scanner used for this work are in agreement with the performances declared by the manufacturers. For the clinical studies, the results obtained using TrueX algorithm showed an increase in SUVmax and SUVmean of 20% and 10% respectively for lesions with volume higher than 2 cm3 and of about 26% and 15% for smaller lesions. The enhancement of SUVmean was around 10% for in axis lesions and of about 12% for off axis lesions. For SUVmax the increase was 23% for both the positions. For small lesions TrueX algorithm led to a metabolic volume higher than with the iterative one while no significant differences were found for big lesions.
  
  
  CONCLUSIONS
  The advances in 3D PET reconstruction algorithms lead to images with improved quantitative accuracy and image quality performance.
authors.affiliation: Medical Physics Unit, Centro Oncologico Fiorentino, Florence, Italy. lucia.orlandini@lacittadellasalute.it
authors.forename: L C
authors.initials: LC
authors.lastname: Orlandini
authors.forename: M
authors.initials: M
authors.lastname: Betti
authors.forename: C
authors.initials: C
authors.lastname: Fulcheri
authors.forename: M
authors.initials: M
authors.lastname: Dona
authors.forename: D
authors.initials: D
authors.lastname: Fisicaro
authors.forename: A
authors.initials: A
authors.lastname: Castagnoli
mesh_terms: D000465:Algorithms; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D009369:Neoplasms / Q000175:diagnosis*; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18