Boel Kullendorff

Diagnostic accuracy of direct digital dental radiography for the detection of periapical bone lesions. II. Effects on diagnostic accuracy after application of image processing

OBJECTIVES The diagnostic accuracy of direct digital radiography for the detection of small experimentally made periapical lesions was evaluated. A comparison was made between original digital images and images processed with different enhancement facilities of the digital system. STUDY DESIGN Seven observers assessed the digital images in original mode and after individual image treatment. The diagnostic accuracy was calculated. The processing functions used by the observers were recorded, and the effect of processing was evaluated. RESULTS The overall diagnostic accuracy was not different for the two image modes. Neither were the individual results of the observers different. The image processing was most effective when alterings of contrast and brightness were used. More complicated processing procedures had less effect on the diagnostic accuracy. CONCLUSIONS Image processing of direct digital images of high quality has a limited effect on the diagnostic accuracy. Basic processing functions, that is, alterings of contrast and brightness, were preferred for the detection of periapical lesions.

Diagnostic accuracy of direct digital dental radiography for the detection of periapical bone lesions: overall comparison between conventional and direct digital radiography.

OBJECTIVES The diagnostic accuracy of direct digital radiography for the detection of small, experimentally made, periapical lesions was compared with that of E speed film. The high- and low-contrast resolutions of the imaging systems were also compared. STUDY DESIGN The high-contrast resolution was evaluated with a line pair plate. The low-contrast resolution was determined with a contrast-detail plexiglass phantom. To evaluate the diagnostic accuracy, the periapical region of dry human mandibles was examined. Receiver operating characteristic based on the readings of seven observers were generated. RESULTS The high-contrast resolution of the digital system was inferior, but the low-contrast resolution was comparable to that of E-speed film. For diagnostic accuracy no significant difference was seen between the areas under the receiver operating characteristic curves. CONCLUSIONS The quality of the direct digital images is comparable to that of E-speed film for the detection of periapical bone lesions.

Subtraction radiography of interradicular bone lesions

Subtraction and conventional radiography were evaluated for their diagnostic potential to assess interradicular bone lesions in the mandibular premolar region. Both conventional radiographs and subtraction images were interpreted by 10 observers. The receiver-operating characteristic (ROC) technique was used to compare the two techniques. The diagnostic validity was higher for the subtraction technique, both for lesions confined to cancellous bone and for lesions including the cortical bone, than for the conventional technique. For bone defects confined to cancellous bone the diagnostic accuracy was lower than those reported from periapical bone lesions irrespective of whether subtraction or conventional radiography was used. We conclude that subtraction radiography improves the detectability of bone lesions, shallow ones in particular. Lesions in the interradicular bone are more difficult to detect than those in the periapical bone.