title: Serial changes of FDG uptake and diagnosis of suspected lung malignancy: a lesion-based analysis.
abstract: OBJECTIVE
  This study prospectively evaluates the serial change of FDG uptake and its diagnostic value in malignant versus benign lung lesions in patients with suspected lung cancer.
  
  
  METHODS
  Patients with suspected lung malignancy underwent whole-body FDG PET/CT at 1, 2, and 3 hours after an IV injection of F-FDG. The SUVs of FDG in lung nodules and hilar/mediastinal nodes at each time point were correlated with biopsy/surgical pathologic findings.
  
  
  RESULTS
  There were a total of 45 malignant lesions and 80 benign lesions from 43 patients with pathologic diagnosis that were included for analysis. The SUVmax had an average of 25.5% increase in all tumor-positive lesions from 1 to 2 hours (vs 1.6% decrease in all tumor-negative lesions, P < 0.0001) and an average of 39.1% increase from 1 to 3 hours (vs 4.5% increase in all tumor-negative lesions, P < 0.0001). The receiver operating characteristic analysis showed that the 2-hour and 3-hour SUVmax had similar area under the curve and outperformed the SUVmax on the 1-hour initial imaging or retention index (RI). The optimal cutoff values to differentiate malignancy from benign lesions were 3.24 for 1-hour SUVmax, 3.67 for 2-hour SUVmax, and 4.21 for 3-hour SUVmax, with 11.6% for 1- to 2-hour RI and 23.9% for 1- to 3-hour RI. The 3-hour delayed SUVmax of 4.21 provided the best overall performance (accuracy of 88.8%). The analysis of the lesion-to-background ratio revealed that delayed imaging improved the image quality significantly, leading to much easier detection of either malignant or benign lesions.
  
  
  CONCLUSIONS
  Multiple time point FDG PET/CT imaging moderately improves the diagnostic accuracy of lung cancer and significantly improves the image quality.
authors.affiliation: From the *Department of Radiology, Philadelphia VA Medical Center; and †Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA.
authors.forename: Gang
authors.initials: G
authors.lastname: Cheng
authors.forename: Abass
authors.initials: A
authors.lastname: Alavi
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Werner
authors.forename: Catherine V
authors.initials: CV
authors.lastname: Del Bello
authors.forename: Scott R
authors.initials: SR
authors.lastname: Akers
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001692:Biological Transport; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D012372:ROC Curve; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18