title: The prognostic value of tumor shadow disappearance rate on integrated PET/CT evaluation of solitary pulmonary nodules with low glucose metabolism.
abstract: OBJECTIVE
  This study aimed to determine the prognostic value of the tumor shadow disappearance rate (TDR) on integrated PET/computed tomography (PET/CT) evaluation of solitary pulmonary nodules (SPNs) with low glucose uptake.
  
  
  METHODS
  From January 2008 to September 2010, 99 patients who underwent fluorine-18 fluorodeoxyglucose PET (F-FDG-PET)/CT scanning for the evaluation of SPNs with a maximum standardized uptake value (SUVmax) below 2.75 (2.5+10%) were retrospectively reviewed. Among the 99 SPNs from these patients, 67 were malignant and 32 were benign, based on surgical pathology. Differences in baseline characteristics between the two groups were examined by means of the independent t-test, the Mann-Whitney U-test, and the χ-test. To test the efficacy of TDR for determining malignancy, the sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and positive and negative likelihood ratios (LR+ and LR-, respectively) with 95% confidence intervals were calculated using the pathological test as the gold standard.
  
  
  RESULTS
  Patients with malignant nodules were older than those with benign nodules (64.5 vs. 55.1 years, respectively, P<0.001) and had higher TDRs (0.8 vs. 0.3, respectively, P<0.001). The optimal cutoff point for the TDR was 0.4886 where the sensitivity, specificity, positive predictive value, and negative predictive value were 0.851, 0.844, 0.919, and 0.730, respectively, and the LR+ and LR- were 5.443 and 0177, respectively. A significant negative correlation between TDR and SUVmax was found only in the malignant group.
  
  
  CONCLUSIONS
  The diagnostic value of TDR complements the PET/CT evaluation of SPNs with a low F-FDG uptake.
authors.affiliation: Departments of aNuclear Medicine bRadiology, Taipei Veterans General Hospital cDepartment of Biomedical Imaging and Radiological Sciences, National Yang-Ming University dSchool of Medicine, National Defense Medical Center, Taipei City, Taiwan ROC.
authors.forename: Ko-Han
authors.initials: KH
authors.lastname: Lin
authors.forename: Rhuen-Chuan
authors.initials: RC
authors.lastname: Lee
authors.forename: Ren-Shyan
authors.initials: RS
authors.lastname: Liu
authors.forename: Chih-Yung
authors.initials: CY
authors.lastname: Chang
mesh_terms: D000328:Adult; D001692:Biological Transport; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography; D011379:Prognosis; D012189:Retrospective Studies; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology; D047368:Tumor Burden
chemical_list: D005947:Glucose