title: Impact of time-of-flight and point-spread-function in SUV quantification for oncological PET.
abstract: BACKGROUND
  Accuracy in the quantification of the SUV is a critical point in PET because proper quantification of tumor uptake is essential for therapy monitoring and prognosis evaluation. Recent advances such as time-of-flight (TOF) and point-spread-function (PSF) reconstructions have dramatically improved detectability. However, first experiences with these techniques have shown a consistent tendency to measure markedly high SUV values, bewildering nuclear medicine physicians and referring clinicians.
  
  
  OBJECTIVE
  We investigated different reconstruction and quantification procedures to determine the optimum protocol for an accurate SUV quantification in last generation PET scanners.
  
  
  METHODS
  Both phantom and patient images were evaluated. A complete set of experiments was performed using a body phantom containing 6 spheres with different background levels and contrasts. Whole-body FDG PET/CT of 20 patients with breast and lung cancer was evaluated. One hundred five foci were identified by 2 experienced nuclear medicine physicians.Each acquisition was reconstructed both with classical and advanced (TOF, PSF) reconstruction techniques. Each sphere and each in vivo lesion was quantified with different parameters as follows: SUV(max), SUV(mean), and SUV(50) (mean within a 50% isocontour).
  
  
  RESULTS
  This study has confirmed that quantification with SUV(max) produces important overestimation of metabolism in new generation PET scanners. This is a relevant result because, currently, SUV(max) is the standard parameter for quantification. SUV(50) has been shown as the best alternative, especially when applied to images reconstructed with PSF + TOF.
  
  
  CONCLUSIONS
  SUV(50) provides accurate quantification and should replace SUV(max) in PET tomographs incorporating advanced reconstruction techniques. PSF + TOF reconstruction is the optimum for both detection and accurate quantification.
authors: Department of Nuclear Medicine, Clínica Universidad de Navarra, Pamplona, Spain.
authors: Elena
authors: E
authors: Prieto
authors: Inés
authors: I
authors: Domínguez-Prado
authors: María José
authors: MJ
authors: García-Velloso
authors: Iván
authors: I
authors: Peñuelas
authors: José Ángel
authors: JÁ
authors: Richter
authors: Josep Maria
authors: JM
authors: Martí-Climent
mesh_terms: D001692:Biological Transport; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism; D064847:Multimodal Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D051598:Whole Body Imaging