title: Dual-time-point 18F-FDG PET imaging for diagnosis of disease type and disease activity in patients with idiopathic interstitial pneumonia.
abstract: OBJECTIVE
  Individual clinical courses of idiopathic interstitial pneumonia (IIP) are variable and difficult to predict because the pathology and disease activity are contingent, and chest computed tomography (CT) provides little information about disease activity. In this study, we applied dual-time-point [(18)F]-fluoro-2-deoxy-D-glucose ((18)F-FDG) positron emission tomography (PET), commonly used for diagnosis of malignant tumours, to the differential diagnosis and prediction of disease progression in IIP patients.
  
  
  METHODS
  Fifty patients with IIP, including idiopathic pulmonary fibrosis (IPF, n = 21), non-specific interstitial pneumonia (NSIP, n = 18) and cryptogenic organizing pneumonia (COP, n = 11), underwent (18)F-FDG PET examinations at two time points: scan 1 at 60 min (early imaging) and scan 2 at 180 min (delayed imaging) after (18)F-FDG injection. The standardized uptake values (SUV) at the two points and the retention index (RI-SUV) calculated from them were evaluated and compared with chest CT findings, disease progression and disease types. To evaluate short-term disease progression, all patients were examined by pulmonary function test every 3 months for 1 year after (18)F-FDG PET scanning.
  
  
  RESULTS
  The early SUV for COP (2.47 +/- 0.74) was significantly higher than that for IPF (0.99 +/- 0.29, p = 0.0002) or NSIP (1.22 +/- 0.44, p= 0.0025). When an early SUV cut-off value of 1.5 and greater was used to distinguish COP from IPF and NSIP, the sensitivity, specificity and accuracy were 90.9, 94.3 and 93.5%, respectively. The RI-SUV for IPF and NSIP lesions was significantly greater in patients with deteriorated pulmonary function after 1 year of follow-up (progressive group, 13.0 +/- 8.9%) than in cases without deterioration during the 1-year observation period (stable group, -16.8 +/- 5.9%, p < 0.0001). However, the early SUV for all IIP types provided no additional information of disease progression. When an RI-SUV cut-off value of 0% and greater was used to distinguish progressive IIPs from stable IIPs, the sensitivity, specificity and accuracy were 95.5, 100 and 97.8%, respectively.
  
  
  CONCLUSIONS
  Early SUV and RI-SUV obtained from dual-time-point (18)F-FDG PET are useful parameters for the differential diagnosis and prediction of disease progression in patients with IIP.
authors.affiliation: Department of Respiratory Medicine, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui, 910-1193, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Umeda
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Demura
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ishizaki
authors.forename: Shingo
authors.initials: S
authors.lastname: Ameshima
authors.forename: Isamu
authors.initials: I
authors.lastname: Miyamori
authors.forename: Yuji
authors.initials: Y
authors.lastname: Saito
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Tsuchida
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Fujibayashi
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Okazawa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D054988:Idiopathic Interstitial Pneumonias / Q000000981:diagnostic imaging* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D013902:Radiography, Thoracic; D013909:Thorax / Q000000981:diagnostic imaging / Q000473:pathology; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18