Detection of Bone Mineral Density Changes by Subtraction of Cone-Beam Computed Tomography Images: A Pilot Study

Abstract

The objective in this study was to investigate the feasibility of digital subtraction technique using cone beam computed tomography (CBCT) images to assess mineral density changes in dry mandibular bone tissue. A simulated procedure to mimic periapical bone loss was performed in 12 alveolar sockets of a dry mandible by controlled application of 0.1ml of a 70% perchloric acid solution. Digital periapical radiographs and CBCT exams were taken at baseline and after 2, 4 and 24hours. Simulated mineral gain was also performed in four alveolar sockets using a bone substitute in differing amounts (baseline, 0.07 and 0.14g) aggregated in a wax medium. All images were subtracted from baseline, resulting in four subtracted images (S 0-S 1-S 2-S 3) for simulated bone loss and three subtracted images for mineral gain (S 0-S 1-S 2) from periapical radiographs and CBCT. Quantitative analysis of mineral density was performed to assess pixel value changes in a grey scale ranging from 0 (black) to 255 (white) pixels. A gradual decrease in pixel values from S 0 to S 3 was observed in all images (p<0.001). Pairwise comparison between periapical radiographs and CBCT slices showed no significant differences, although the subtle changes in the S 1 images (after 2hours) were less apparent in the periapical radiographs. A continuous progressive gain in mineral bone was also observed from baseline to S 1 and S 2. The results suggest that subtracted CBCT images can be used to monitor mineral bone changes based on the pixel grey values of images, with potential application for evaluation of bone repair.

Application of platelet -rich fibrin with β-tricalcium phosphate for reconstruction of bone in periapical defects

“…These slight changes, could hardly be detected in visual analysis (22) . However, these changes could be identified and quantitatively measured by means of pixel grey values using CBCT (23) . Therefore, in this study it was possible to detect subtle changes in bone density at the periapical region using quantitative pixel measurement in CBCT images.…”