title: Performance of ACR Lung-RADS in a clinical CT lung screening program.
abstract: OBJECTIVE
  The aim of this study was to assess the effect of applying ACR Lung-RADS in a clinical CT lung screening program on the frequency of positive and false-negative findings.
  
  
  METHODS
  Consecutive, clinical CT lung screening examinations performed from January 2012 through May 2014 were retroactively reclassified using the new ACR Lung-RADS structured reporting system. All examinations had initially been interpreted by radiologists credentialed in structured CT lung screening reporting following the National Comprehensive Cancer Network's Clinical Practice Guidelines in Oncology: Lung Cancer Screening (version 1.2012), which incorporated positive thresholds modeled after those in the National Lung Screening Trial. The positive rate, number of false-negative findings, and positive predictive value were recalculated using the ACR Lung-RADS-specific positive solid/part-solid nodule diameter threshold of 6 mm and nonsolid (ground-glass) threshold of 2 cm. False negatives were defined as cases reclassified as benign under ACR Lung-RADS that were diagnosed with malignancies within 12 months of the baseline examination.
  
  
  RESULTS
  A total of 2,180 high-risk patients underwent baseline CT lung screening during the study interval; no clinical follow-up was available in 577 patients (26%). ACR Lung-RADS reduced the overall positive rate from 27.6% to 10.6%. No false negatives were present in the 152 patients with >12-month follow-up reclassified as benign. Applying ACR Lung-RADS increased the positive predictive value for diagnosed malignancy in 1,603 patients with follow-up from 6.9% to 17.3%.
  
  
  CONCLUSIONS
  The application of ACR Lung-RADS increased the positive predictive value in our CT lung screening cohort by a factor of 2.5, to 17.3%, without increasing the number of examinations with false-negative results.
authors.affiliation: Department of Radiology, Lahey Hospital & Medical Center, Burlington, Massachusetts. Electronic address: brady.mckee@lahey.org.
authors.forename: Brady J
authors.initials: BJ
authors.lastname: McKee
authors.affiliation: Department of Radiation Oncology, Lahey Hospital & Medical Center, Burlington, Massachusetts.
authors.forename: Shawn M
authors.initials: SM
authors.lastname: Regis
authors.affiliation: Department of Radiation Oncology, Lahey Hospital & Medical Center, Burlington, Massachusetts.
authors.forename: Andrea B
authors.initials: AB
authors.lastname: McKee
authors.affiliation: Department of Radiology, Lahey Hospital & Medical Center, Burlington, Massachusetts.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Flacke
authors.affiliation: Department of Radiology, Lahey Hospital & Medical Center, Burlington, Massachusetts.
authors.forename: Christoph
authors.initials: C
authors.lastname: Wald
mesh_terms: D003951:Diagnostic Errors / Q000517:prevention & control* / Q000706:statistics & numerical data; D055088:Early Detection of Cancer / Q000592:standards* / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011785:Quality Assurance, Health Care / Q000379:methods / Q000706:statistics & numerical data; D011873:Radiology Information Systems / Q000592:standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000592:standards* / Q000706:statistics & numerical data*; D014481:United States
keywords: CT lung screening; Lung-RADS