title: The influence of respiratory motion on the cumulative SUV-volume histogram and fractal analyses of intratumoral heterogeneity in PET/CT imaging.
abstract: OBJECTIVE
  The purpose of this study was to investigate the influence of respiratory motion on the evaluation of the intratumoral heterogeneity of FDG uptake using cumulative SUV-volume histogram (CSH) and fractal analyses.
  
  
  METHODS
  We used an NEMA IEC body phantom with a homogeneous hot sphere phantom (HO) and two heterogeneous hot sphere phantoms (HE1 and HE2). The background radioactivity of (18)F in the NEMA phantom was 5.3 kBq/mL. The ratio of radioactivity was 4:2:1 for the HO and the outer rims of the HE1 and HE2 phantoms, the inner cores of the HE1 and HE2 phantoms, and background, respectively. Respiratory motion was simulated using a motion table with an amplitude of 2 cm. PET/CT data were acquired using Biograph mCT in motionless and moving conditions. The PET images were analyzed by both CSH and fractal analyses. The area under the CSH (AUC-CSH) and the fractal dimension (FD) was used as quantitative metrics.
  
  
  RESULTS
  In motionless conditions, the AUC-CSHs of the HO (0.80), HE1 (0.75) and HE2 (0.65) phantoms were different. They did not differ in moving conditions (HO, 0.63; HE1, 0.65; HE2, 0.60). The FD of the HO phantom (0.77) was smaller than the FDs of the HE1 (1.71) and HE2 (1.98) phantoms in motionless conditions; however, the FDs of the HO (1.99) and HE1 (2.19) phantoms were not different from each other and were smaller than that of the HE2 (3.73) phantom in moving conditions.
  
  
  CONCLUSIONS
  Respiratory motion affected the results of the CSH and fractal analyses for the evaluation of the heterogeneity of the PET/CT images. The influence of respiratory motion was considered to vary depending on the object size.
authors.affiliation: Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. t.takeshita.1227@gmail.com.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Takeshita
authors.affiliation: Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Keishin
authors.initials: K
authors.lastname: Morita
authors.affiliation: Division of Radiology, 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.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kidera
authors.affiliation: Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Mikasa
authors.affiliation: Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Maebatake
authors.affiliation: Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Akamatsu
authors.affiliation: Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Miwa
authors.affiliation: Division of Radiology, Department of Medical Technology, Kyushu University Hospital, Fukuoka, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Baba
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: D016477:Artifacts; D001692:Biological Transport; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D017709:Fractals; D007091:Image Processing, Computer-Assisted; D009068:Movement; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D019047:Phantoms, Imaging; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D012119:Respiration
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: Cumulative SUV-volume histogram analysis; Fractal analysis; PET/CT; Respiratory motion