title: Grey-scale inversion improves detection of lung nodules.
abstract: The current study aims to establish whether detection of solitary pulmonary nodules can be improved by inverting the grey scale of posteroanterior (PA) chests.
  
  
  
  30 PA chest images were presented on 2 occasions to 16 senior radiologists on either primary or secondary class displays in the standard or inverted mode. 15 images within each group contained a single nodule positioned in a range of anatomical sites. A receiver operating characteristic (ROC) methodology was used to explore differences between the presentation modes.
  
  
  
  Improved ROC scores were evident with inverted (Az 0.77) compared with standard (Az 0.73) (p=0.02) images; however, this difference was seen only with the primary displays. The benefits seen are most likely owing to increased nodule luminance with the inverted images, particularly when using primary displays.
  
  
  
  This study demonstrates that the inverted image can offer advantages in lung nodule detection over the standard presentation mode when images are viewed on high-specification viewing systems. The study has demonstrated that there is an improvement in the detectability of lung nodules on an inverted image with a primary display monitor that is not evident with secondary displays. This is likely to be the result of increased nodule luminance on primary displays when images are presented in the inverted mode.
authors.affiliation: Discipline of Medical Radiation Sciences, University of Sydney, Sydney, Australia. john.robinsonmrs@sydney.edu.au
authors.forename: J W
authors.initials: JW
authors.lastname: Robinson
authors.forename: J T
authors.initials: JT
authors.lastname: Ryan
authors.forename: M F
authors.initials: MF
authors.lastname: McEntee
authors.forename: S J
authors.initials: SJ
authors.lastname: Lewis
authors.forename: M G
authors.initials: MG
authors.lastname: Evanoff
authors.forename: L A
authors.initials: LA
authors.lastname: Rainford
authors.forename: P C
authors.initials: PC
authors.lastname: Brennan
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011856:Radiographic Image Enhancement / Q000379:methods*; D013902:Radiography, Thoracic / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*