Graph Cuts-based Segmentation of Alveolar Bone in Ultrasound Imaging

Abstract

Alveolar bone is a part of the periodontium complex supporting the teeth. Conventional radiography and cone-beam computed tomography are currently used to image the alveolar bones. Recently, ionizing radiation-free ultrasound has shown promising potential to image dento-periodontium. However, the ability to visualize alveolar bones in ultrasound images is a challenge for the dentists who are novice to ultrasonography. This study proposes a semi-automated technique to segment alveolar bone by using a multi-label graph cuts optimization approach, where the K-means clustering of intensity values was used in constructing the initial graph. A homomorphic filter was employed as a preprocessing step to de-noise the ultrasound data. The approach was evaluated by over 15 ultrasound images acquired from fresh porcine specimens. Four quantitative evaluators, namely Dice coefficient, sensitivity, specificity, and Hausdorff distance were measured from the proposed method and the manual ground truth by an expert orthodontist. The inter-rater and intra-rater variabilities were also calculated using the delineations by three raters with different levels of experience. The study has demonstrated that the proposed segmentation method provides consistent, reliable, and accurate results among raters and thus has potential to be used as a tool to help dentists to delineate alveolar bones for further analysis.