title: Accuracy in detecting bone lesions in vitro with conventional and subtracted direct digital imaging.
abstract: OBJECTIVE
  To implement direct digital imaging (DDI) in subtraction radiography and compare the accuracy of conventional and subtracted DD images in detecting small bone lesions in vitro.
  
  
  METHODS
  Alveolar bone defects were produced in a section of a pig mandible, with slow-speed burs 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.4 mm in diameter. Standardized DD images were subtracted and displayed in black and white, contrast-enhanced and pseudo-colour transformed formats. 370 pairs of slides taken directly from the computer monitor were evaluated by eight observers.
  
  
  RESULTS
  The area P(A) under the ROC curve with DDI was 0.67 +/- 0.1. This was significantly lower (p < 0.001) than any of the three modes of subtraction radiography (mean P(A) = 0.88 +/- 0.09). The detection of small lesions (bur diameter 0.6 mm) was significantly better (p < 0.001) with contrast enhancement. Observer agreement was smaller for DDI (chi = 0.22 +/- 0.09) compared with the subtraction images (mean chi 0.64 +/- 0.13) (p < 0.001).
  
  
  CONCLUSIONS
  The diagnostic characteristics of the DDI system were significantly improved by digital subtraction with image processing.
authors.affiliation: School of Dental Medicine, University of Bern, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Stassinakis
authors.forename: U
authors.initials: U
authors.lastname: Brägger
authors.forename: M
authors.initials: M
authors.lastname: Stojanovic
authors.forename: W
authors.initials: W
authors.lastname: Bürgin
authors.forename: A
authors.initials: A
authors.lastname: Lussi
authors.forename: N P
authors.initials: NP
authors.lastname: Lang
mesh_terms: D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging*; D000704:Analysis of Variance; D000818:Animals; D008334:Mandible / Q000000981:diagnostic imaging / Q000473:pathology; D008336:Mandibular Diseases / Q000000981:diagnostic imaging*; D012372:ROC Curve; D011856:Radiographic Image Enhancement; D019252:Radiography, Dental, Digital; D012815:Signal Processing, Computer-Assisted; D013382:Subtraction Technique; D013552:Swine