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

Objective. The purpose of this study was to compare a new digital subtracti on system with conventional radiograph images for the detection of periapic al and periodontal bone lesions. Study design. Periapical and periodontal bone lesions were simulated with c ortical bone chips of varying sizes placed on a human dry mandible. Radiogr aphic film images were acquired from varying projections and were subsequen tly digitized, registered, and subtracted. Four clinicians evaluated the su btracted images, and sensitivity and specificity were calculated. Results. The mean sensitivity and specificity of the Diagnostic Subtraction Radiography system for detecting bone lesions of all sizes with varying pr ojection geometry were 87.90% and 85.23%, respectively. The corresponding r esults for conventional radiograph images were 47.54% and 97.38%. The diffe rence in sensitivity was statistically significant, whereas the difference in specificity was not. Conclusions. These results indicate that, even when radiographs are taken f rom disparate projection geometries, the Diagnostic Subtraction Radiography system is capable of excellent discrimination between healthy and disease states in this in vitro model.