title: Accuracy of amplitude-based respiratory gating for PET/CT in irregular respirations.
abstract: OBJECTIVE
  We evaluated the accuracy of amplitude gating PET (AG-PET) compared with phase gating PET (PG-PET) in relation to respiratory motion patterns based on a phantom analysis.
  
  
  METHODS
  We used a NEMA IEC body phantom filled with an (18)F solution with a 4:1 sphere-to-background radioactivity ratio (12.6 and 2.97 kBq/mL). PET/CT scans were acquired in a motionless and moving state on a Biograph mCT. The respiratory movements were simulated by four different waveform patterns consisting of ideal breathing, breathing with a pause period, breathing with a variable amplitude and breathing with a changing baseline. AG-PET selects the narrow bandwidth containing 20 % of the respiratory cycle. PG-PET was reconstructed with five gates. The image quality was physically assessed using the percent contrast (Q H,10mm), background variability (N 10mm) recovery coefficient (RC), and sphere volumes.
  
  
  RESULTS
  In regular motion patterns with ideal breathing and breathing with a pause period, the Q H,10mm, RC and sphere volumes were not different between AG-PET and PG-PET. In the variable amplitude pattern, the Q H,10mm of AG-PET was higher than that of PG-PET (35.8 vs 28.2 %), the RC of AG-PET was higher than that of PG-PET and sphere volume of AG-PET was smaller than that of PG-PET (6.4 vs 8.6 mL). In the changing baseline pattern, the Q H,10mm of AG-PET was higher than that of PG-PET (42.4 vs 16.7 %), the RC of AG-PET was higher than that of PG-PET and sphere volume of AG-PET was smaller than that of PG-PET (6.2 vs 9.8 mL). The N 10mm did not differ between AG-PET and PG-PET, irrespective of the motion pattern.
  
  
  CONCLUSIONS
  Amplitude gating PET is considered to be more accurate than phase gating PET for examining unstable respiratory motion patterns, such as those involving a variable amplitude or changing baseline.
authors.affiliation: Division of Radiology, Department of Medical Technology, Kyushu University Hospital, Fukuoka, Japan, yuji1006@med.kyushu-u.ac.jp.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tsutsui
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kidera
authors.forename: Takafumi
authors.initials: T
authors.lastname: Taniguchi
authors.forename: Go
authors.initials: G
authors.lastname: Akamatsu
authors.forename: Isao
authors.initials: I
authors.lastname: Komiya
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Umezu
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kitamura
authors.forename: Shingo
authors.initials: S
authors.lastname: Baba
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sasaki
mesh_terms: D016477:Artifacts; D005462:Fluorine Radioisotopes / Q000737:chemistry; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D009068:Movement; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D012119:Respiration; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D005462:Fluorine Radioisotopes