title: Standard versus inverted digital luminescence radiography in detecting pulmonary nodules: a ROC analysis.
abstract: OBJECTIVE
  Observer performance tests were conducted to compare the effect of presenting digital luminescence radiography (DLR) monitor images in positive mode ("bones black") or negative mode ("bones white") in the detectability of subtle lung nodules.
  
  
  METHODS
  Five radiologists independently reviewed digital radiographs of 55 patients with either (a) a single, small (6-12 mm), non- calcified peripheral nodule confirmed by chest CT (n=47) or (b) normal finding (n=8) confirmed by chest CT, respectively. Mean size of pulmonary nodules was 8.3mm (range 6-12 mm, median 7 mm). Radiographs were displayed either in standard mode (bones white) or inverse intensity (bones black). A total of 550 observations resulted. For the evaluation ROC analysis was performed using a specialized computer algorithm.
  
  
  RESULTS
  The standard presentation mode showed a sensitivity of 61.7% and a specificity of 72.5%, the inverse presentation mode a sensitivity of 68.1% and a specificity of 75.0%. ROC- analysis showed that the difference between the standard mode (Az- value 0.694) and the inverse mode (Az- value 0.810) was significant in favour of the inverse presentation mode (p=0.001). This finding was especially observed in more experienced radiologist (Az- values 0.716 vs. 0.909, P<0.001).
  
  
  CONCLUSIONS
  Our study demonstrates a significant advantage of the inverse mode in the detection of small pulmonary nodules compared with the commonly used negative mode when interpreted by more experienced radiologists.
  
  
  CONCLUSIONS
  Inverse intensity images ("bones black") may have some advantages in the detection of small pulmonary nodules in experienced readers when presented on a stand-alone display.
authors.affiliation: Department of Diagnostic and Interventional Radiology, Allgemeines Krankenhaus, Hagen, Germany. kirchner@akh-hagen.de
authors.forename: Johannes
authors.initials: J
authors.lastname: Kirchner
authors.forename: Darius
authors.initials: D
authors.lastname: Gadek
authors.forename: Jan-Peter
authors.initials: JP
authors.lastname: Goltz
authors.forename: Anna
authors.initials: A
authors.lastname: Doroch-Gadek
authors.forename: Sven
authors.initials: S
authors.lastname: Stückradt
authors.forename: Dieter
authors.initials: D
authors.lastname: Liermann
authors.forename: Ralph
authors.initials: R
authors.lastname: Kickuth
mesh_terms: D006801:Humans; D008163:Luminescent Measurements / Q000379:methods*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D015588:Observer Variation; D012372:ROC Curve; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*
keywords: Chest x-ray; DLR; Gray- scale reversal; Pulmonary mass