title: Impact of Time-of-Flight PET/CT with a Large Axial Field of View for Reducing Whole-Body Acquisition Time.
abstract: The aim of this study was to evaluate the imaging performance of 39- and 52-ring time-of-flight (TOF) PET/CT scanners. We also assessed the potential of reducing the scanning time using a 52-ring TOF PET/CT scanner.
  
  
  METHODS
  PET/CT scanners with 39- and 52-ring lutetium oxyorthosilicate detectors were evaluated. The axial fields of view were 16.2 and 21.6 cm, respectively. We used a National Electrical Manufacturers Association International Electrotechnical Commission body phantom filled with an (18)F solution containing background activity of 5.31 and 2.65 kBq/mL for the studies. The sphere-to-background ratio was 4:1. The PET data were acquired for 10 min in 3-dimensional list mode and then reconstructed with both ordered-subsets reconstruction maximization and ordered-subsets reconstruction maximization plus point-spread function plus time-of-flight algorithms. PET images with different acquisition times were reconstructed (from 1 to 10 min). The image quality was physically assessed using the sensitivity, noise-equivalent counting rate, coefficient of variation of background activity, and relative recovery coefficient.
  
  
  RESULTS
  The total system sensitivities of the 39- and 52-ring scanners were 5.6 and 9.3 kcps/MBq, respectively. Compared with the 39-ring scanner, the noise-equivalent counting rate of the 52-ring scanner was 60% higher for both the high-activity and the low-activity models. The recovery coefficient was consistent, irrespective of the number of detector rings. The coefficient of variation of the 52-ring scanner using a 3-min acquisition time was equivalent to that of the 39-ring scanner using a 4-min acquisition time.
  
  
  CONCLUSIONS
  The image quality of the 52-ring scanner is superior to that of the 39-ring scanner. The acquisition time per bed position of the 52-ring system can be reduced by about 25% without compromising image quality. In addition, the number of bed positions required is 25% lower for the 52-ring system. Finally, the examination time required for a whole-body PET scan is considered to be reduced by about 40% if the 52-ring scanner is used.
authors.affiliation: Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan Division of Molecular Imaging, Institute of Biomedical Research and Innovation, Kobe Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Akamatsu
authors.affiliation: Department of Radiological Technology, Saga University Hospital, Saga, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Uba
authors.affiliation: Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Taniguchi
authors.affiliation: Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Mitsumoto
authors.affiliation: Department of Radiological Technology, Saga University Hospital, Saga, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Narisue
authors.affiliation: Department of Medical Technology, Kyushu University Hospital, Fukuoka, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tsutsui
authors.affiliation: Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan msasaki@hs.med.kyushu-u.ac.jp.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sasaki
mesh_terms: D006801:Humans; D064847:Multimodal Imaging / Q000009:adverse effects / Q000295:instrumentation*; D049268:Positron-Emission Tomography / Q000009:adverse effects / Q000295:instrumentation*; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000009:adverse effects / Q000295:instrumentation*; D051598:Whole Body Imaging / Q000009:adverse effects / Q000295:instrumentation*
keywords: PET/CT; axial field of view; image quality; sensitivity; time-of-flight