title: Formula corrected maximal standardized uptake value in FDG-PET for partial volume effect and motion artifact is not a prognostic factor in stage I non-small cell lung cancer treated with stereotactic body radiotherapy.
abstract: OBJECTIVE
  It is known that the partial volume effect and respiratory motion blur affect quantitative parameters such as the maximum standardized uptake value (SUVmax) in FDG-PET, especially in small lesions. The purpose of this study was to assess the prognostic value of corrected SUVmax, which was corrected SUVmax for the partial volume effect and respiratory motion blur, in patients with stage I non-small cell lung cancer (NSCLC) after treatment with stereotactic body radiotherapy (SBRT).
  
  
  METHODS
  Fifty-one patients who were treated with SBRT between 2005 and 2011 in our institute were enrolled. The median tumor diameter was 2.2 cm (range 0.9-3.9 cm). The prescribed dose was typically 48 Gy in 4 fractions, 60 Gy in 8 fractions or 60 Gy in 15 fractions to the isocenter of irradiation fields. Each raw SUVmax was corrected using the recently proposed formula, and the correlations of raw SUVmax and corrected SUVmax with local control rate (LCR) were analyzed retrospectively.
  
  
  RESULTS
  Median raw SUVmax before SBRT was 6.4 (range 0.6-22.8). Median corrected SUVmax was 8.0 (range 0.8-22.8), which was significantly increased (p < 0.01). The median follow-up period for survivors was 45.3 months (range 18.5-82.0 months). The 3-year LCR and overall survival rates were 81.8 and 65.2 %, respectively. In univariate analysis, raw SUVmax [per 1 increase; p = 0.02, hazard ratio (HR) 1.20, 95 % confidence interval (CI) 1.03-1.42] was significantly correlated with LCR, but corrected SUVmax did not show a significant correlation with LCR (per 1 increase; p = 0.15, HR 1.07, 95 % CI 0.96-1.19). Other factors significantly correlated with LCR were diagnosis (pathological diagnosis vs. clinical diagnosis; p = 0.04, HR 6.17, 95 % CI 1.08-116) and tumor diameter (per 1 mm increase; p < 0.01, HR 1.33, 95 % CI 1.15-1.61).
  
  
  CONCLUSIONS
  Tumor diameter was the most significant predictor of LCR after SBRT. Correction for the partial volume effect and respiratory motion blur may weaken the prognostic value of SUVmax.
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-Ku, Sendai, 980-8574, Japan.
authors.forename: Takaya
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-Ku, Sendai, 980-8574, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kadoya
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-Ku, Sendai, 980-8574, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Shirata
authors.affiliation: Department of Diagnostic Radiology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kaneta
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Koto
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-Ku, Sendai, 980-8574, Japan.
authors.forename: Rei
authors.initials: R
authors.lastname: Umezawa
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-Ku, Sendai, 980-8574, Japan.
authors.forename: Youjirou
authors.initials: Y
authors.lastname: Ishikawa
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-Ku, Sendai, 980-8574, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Kubozono
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-Ku, Sendai, 980-8574, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sugawara
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-Ku, Sendai, 980-8574, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Matsushita
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-Ku, Sendai, 980-8574, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Abe
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-Ku, Sendai, 980-8574, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Takeda
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-Ku, Sendai, 980-8574, Japan. kjingu-jr@rad.med.tohoku.ac.jp.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Jingu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D001692:Biological Transport; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009068:Movement; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011379:Prognosis; D016634:Radiosurgery; D012119:Respiration; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: Corrected SUVmax; Lung cancer; Prognosis; Stereotactic body radiotherapy