title: 18F-Fluorodeoxyglucose positron emission tomography pulmonary imaging in idiopathic pulmonary fibrosis is reproducible: implications for future clinical trials.
abstract: OBJECTIVE
  Noninvasive markers of disease activity in patients with idiopathic pulmonary fibrosis (IPF) are lacking. We performed this study to investigate the reproducibility of pulmonary (18)F-FDG PET/CT in patients with IPF.
  
  
  METHODS
  The study group comprised 13 patients (11 men, 2 women; mean age 71.1 ± 9.9 years) with IPF recruited for two thoracic (18)F-FDG PET/CT studies performed within 2 weeks of each other. All patients were diagnosed with IPF in consensus at multidisciplinary meetings as a result of typical clinical, high-resolution CT and pulmonary function test features. Three methods for evaluating pulmonary (18)F-FDG uptake were used. The maximal (18)F-FDG pulmonary uptake (SUVmax) in the lungs was determined using manual region-of-interest placement. An (18)F-FDG uptake intensity histogram was automatically constructed from segmented lungs to evaluate the distribution of SUVs. Finally, mean SUV was determined for volumes-of-interest in pulmonary regions with interstitial lung changes identified on CT scans. Processing included correction for tissue fraction effects. Bland-Altman analysis was performed and interclass correlation coefficients (ICC) were determined to assess the reproducibility between the first and second PET scans, as well as the level of intraobserver and interobserver agreement.
  
  
  RESULTS
  The mean time between the two scans was 6.3 ± 4.3 days. The interscan ICCs for pulmonary SUVmax analysis and mean SUV corrected for tissue fraction effects were 0.90 and 0.91, respectively. Intensity histograms were different in only 1 of the 13 paired studies. Intraobserver agreement was also excellent (0.80 and 0.85, respectively). Some bias was observed between observers, suggesting that serial studies would benefit from analysis by the same observer.
  
  
  CONCLUSIONS
  This study demonstrated that there is excellent short-term reproducibility in pulmonary (18)F-FDG uptake in patients with IPF.
authors.affiliation: Respiratory Medicine, Lister Hospital, Stevenage, UK.
authors.forename: Thida
authors.initials: T
authors.lastname: Win
authors.forename: Tryphon
authors.initials: T
authors.lastname: Lambrou
authors.forename: Brian F
authors.initials: BF
authors.lastname: Hutton
authors.forename: Irfan
authors.initials: I
authors.lastname: Kayani
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Screaton
authors.forename: Joanna C
authors.initials: JC
authors.lastname: Porter
authors.forename: Toby M
authors.initials: TM
authors.lastname: Maher
authors.forename: Raymondo
authors.initials: R
authors.lastname: Endozo
authors.forename: Robert I
authors.initials: RI
authors.lastname: Shortman
authors.forename: Pauline
authors.initials: P
authors.lastname: Lukey
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Groves
mesh_terms: D000368:Aged; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000000981:diagnostic imaging* / Q000378:metabolism; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D064847:Multimodal Imaging / Q000379:methods*; D049268:Positron-Emission Tomography; D015203:Reproducibility of Results; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18