title: Respiratory-gated time-of-flight PET/CT during whole-body scan for lung lesions: feasibility in a routine clinical setting and quantitative analysis.
abstract: OBJECTIVE
  To demonstrate the feasibility of respiratory gating during whole-body scan for lung lesions in routine18F-FDG PET/CT examinations using a time-of-flight (TOF)-capable scanner to determine the effect of respiratory gating on reduction of both misregistration (between CT and PET) and image blurring, and on improvement of the maximum standardized uptake value (SUVmax).
  
  
  METHODS
  Patients with lung lesions who received FDG PET/CT were prospectively studied. Misregistration, volume of PET (Vp), and SUVmax were compared between ungated and gated images. The difference in respiratory gating effects was compared between lesions located in the upper or middle lobes (UML) and the lower lobe (LL). The correlation between three parameters (% change in misregistration, % change in Vp, and lesion size) and % change in SUVmax was analyzed.
  
  
  RESULTS
  The study population consisted of 60 patients (37 males, 23 females; age 68 ± 12 years) with lung lesions (2.5 ± 1.7 cm). Fifty-eight out of sixty respiratory gating studies were successfully completed with a total scan time of 20.9 ± 1.9 min. Eight patients' data were not suitable for analysis, while the remaining 50 patients' data were analyzed. Respiratory gating reduced both misregistration by 21.4 % (p < 0.001) and Vp by 14.2 % (p < 0.001). The SUVmax of gated images improved by 14.8 % (p < 0.001). The % change in misregistration, Vp, and SUVmax by respiratory gating tended to be larger in LL lesions than in UML lesions. The correlation with % change in SUVmax was stronger in % change in Vp (r = 0.57) than % change in misregistration (r = 0.35). There was no statistically significant correlation between lesion size and % change in SUVmax (r = -0.20).
  
  
  CONCLUSIONS
  Respiratory gating during whole-body scan in routine TOF PET/CT examinations is feasible and can reduce both misregistration and PET image blurring, and improve the SUVmax of lung lesions located primarily in the LL.
authors: Department of Radiology, Ise Red Cross Hospital, 1-471-2 Funae, Ise, Mie, 516-8512, Japan. n-suzawa@clin.medic.mie-u.ac.jp.
authors: Naohisa
authors: http://orcid.org/0000-0001-5675-7078
authors: N
authors: Suzawa
authors: Department of Radiology, Mie University Hospital, Tsu, Mie, Japan.
authors: Yasutaka
authors: Y
authors: Ichikawa
authors: Department of Radiology, Mie University Hospital, Tsu, Mie, Japan.
authors: Masaki
authors: M
authors: Ishida
authors: Department of Radiology, Mie University Hospital, Tsu, Mie, Japan.
authors: Yoya
authors: Y
authors: Tomita
authors: Department of Electronic and Computer Engineering, Ritsumeikan University, Kusatsu, Shiga, Japan.
authors: Ryohei
authors: R
authors: Nakayama
authors: Department of Radiology, Mie University Hospital, Tsu, Mie, Japan.
authors: Hajime
authors: H
authors: Sakuma
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography; D055425:Respiratory-Gated Imaging Techniques; D013997:Time Factors; D051598:Whole Body Imaging; D055815:Young Adult
keywords: Lung; PET/CT; Respiratory gating; Routine; TOF