Analysis of sensitivity and specificity of a new digital subtraction system: An in vitro study

Abstract

The purpose of this study was to compare a new digital subtraction system with conventional radiograph images for the detection of periapical and periodontal bone lesions. Periapical and periodontal bone lesions were simulated with cortical bone chips of varying sizes placed on a human dry mandible. Radiographic film images were acquired from varying projections and were subsequently digitized, registered, and subtracted. Four clinicians evaluated the subtracted images, and sensitivity and specificity were calculated. The mean sensitivity and specificity of the Diagnostic Subtraction Radiography system for detecting bone lesions of all sizes with varying projection geometry were 87.90% and 85.23%, respectively. The corresponding results for conventional radiograph images were 47.54% and 97.38%. The difference in sensitivity was statistically significant, whereas the difference in specificity was not. These results indicate that, even when radiographs are taken from disparate projection geometries, the Diagnostic Subtraction Radiography system is capable of excellent discrimination between healthy and disease states in this in vitro model.