title: High resolution spiral CT for determining the malignant potential of solitary pulmonary nodules: refining and testing the test.
abstract: BACKGROUND
  A solitary pulmonary nodule (SPN) may represent early stage lung cancer. Lung cancer is a devastating disease with an overall 5-year mortality rate of approximately 84% but with early detection and surgery as low as 47%. Currently a contrast-enhanced multiple-row detector CT (MDCT) scan is the first examination when evaluating patients with suspected lung cancer.
  
  
  OBJECTIVE
  To apply an additional high resolution CT (HRCT) to SPNs to test whether certain morphological characteristics are associated with malignancy, to assess the diagnostic accuracy of HRCT in the characterization of SPNs, and to address the reproducibility of all measures.
  
  
  METHODS
  Two hundred and thirteen participants with SPNs were included in a follow-up study. Blinded HRCT images were assessed with regard to margin risk categories (MRCs), calcification patterns and certain other characteristics and overall malignancy potential ratings (MPRs) were given. Morphological characteristics were tested against reference standard and ROC methodology was applied to assess diagnostic accuracy. Reproducibility was measured with Kappa statistics and 95% confidence intervals were computed for all results. Histopathology (90%) and CT follow-up (10%) were used as reference standard.
  
  
  RESULTS
  MRCs (P < 0.001), calcification patterns (P = 0.003), and pleural retraction (P < 0.001) were all statistically significantly associated to malignancy. Reproducibility was moderate to substantial. Sensitivity, specificity, and overall diagnostic accuracy of HRCT were 98%, 23% and 87%, respectively. Reproducibility was substantial.
  
  
  CONCLUSIONS
  Statistically significant associations between SPN MRCs, calcification patterns, pleural retraction and malignancy were found. HRCT yielded a very high sensitivity and a somewhat lower specificity for malignancy. Reproducibility was high.
authors.affiliation: Department of Radiology, Aarhus University Hospital, Denmark. stefhard@rm.dk
authors.forename: Stefan Walbom
authors.initials: SW
authors.lastname: Harders
authors.forename: Hans Henrik
authors.initials: HH
authors.lastname: Madsen
authors.forename: Torben Riis
authors.initials: TR
authors.lastname: Rasmussen
authors.forename: Henrik
authors.initials: H
authors.lastname: Hager
authors.forename: Finn
authors.initials: F
authors.lastname: Rasmussen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000000981:diagnostic imaging; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010994:Pleura / Q000000981:diagnostic imaging; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards