title: The solitary pulmonary nodule on chest radiography: can we really tell if the nodule is calcified?
abstract: OBJECTIVE
  This study was designed to assess the ability of radiologists to accurately detect calcification within a solitary pulmonary nodule with chest radiography.
  
  
  METHODS
  Thirty-five solitary pulmonary nodules that were examined by both posteroanterior and lateral chest radiography and on thin-section CT were retrospectively identified. Fourteen radiologists blinded to the results of CT assessed the nodules for the presence or absence of calcification using chest radiographs alone. The radiologists then assigned one of six values on the basis of their confidence in that assessment. The accuracy and confidence values for each nodule were analyzed on the basis of the presence or absence of calcification as seen on CT. Receiver operating characteristic (ROC) curves were generated.
  
  
  RESULTS
  The positive predictive value of a "definitely calcified" assessment was 0.93. Combining all levels of radiologists' confidence, the sensitivity of the chest radiograph in the detection of calcium was 0.50 and the specificity was 0.87. There was no difference in the confidence levels reported between the calcified and noncalcified nodules, and there was no correlation of nodule size with accuracy or confidence level.
  
  
  CONCLUSIONS
  The ability of radiologists to detect calcium in a solitary pulmonary nodule by chest radiography was low, as defined by the ROC data. Of the "definitely calcified" nodules, up to 7% may not be calcified and may be potentially malignant. Without documentation of long-term stability, a low threshold for recommending CT may be appropriate.
authors.affiliation: Department of Radiology, The University of Arizona, 1501 N. Campbell Ave., Tucson, AZ 85724-5067, USA.
authors.forename: W G
authors.initials: WG
authors.lastname: Berger
authors.forename: W K
authors.initials: WK
authors.lastname: Erly
authors.forename: E A
authors.initials: EA
authors.lastname: Krupinski
authors.forename: J R
authors.initials: JR
authors.lastname: Standen
authors.forename: R G
authors.initials: RG
authors.lastname: Stern
mesh_terms: D000368:Aged; D002114:Calcinosis / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D013902:Radiography, Thoracic; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed