A User-Friendly Protocol for Mandibular Segmentation of CBCT Images for Superimposition and Internal Structure Analysis.

Chenshuang Li,Zhong Zheng,Chun-Hsi Chung,Leanne Lin

doi:10.3390/jcm10010127

Abstract

Background: Since cone-beam computed tomography (CBCT) technology has been widely adopted in orthodontics, multiple attempts have been made to devise techniques for mandibular segmentation and 3D superimposition. Unfortunately, as the software utilized in these methods are not specifically designed for orthodontics, complex procedures are often necessary to analyze each case. Thus, this study aimed to establish an orthodontist-friendly protocol for segmenting the mandible from CBCT images that maintains access to the internal anatomic structures. Methods: The “sculpting tool” in the Dolphin 3D Imaging software was used for segmentation. The segmented mandible images were saved as STL files for volume matching in the 3D Slicer to validate the repeatability of the current protocol and were exported as DICOM files for internal structure analysis and voxel-based superimposition. Results: The mandibles of all tested CBCT datasets were successfully segmented. The volume matching analysis showed high consistency between two independent segmentations for each mandible. The intraclass correlation coefficient (ICC) analysis on 20 additional CBCT mandibular segmentations further demonstrated the high consistency of the current protocol. Moreover, all of the anatomical structures for superimposition identified by the American Board of Orthodontics were found in the voxel-based superimposition, demonstrating the ability to conduct precise internal structure analyses with the segmented images. Conclusion: An efficient and precise protocol to segment the mandible while retaining access to the internal structures was developed on the basis of CBCT images.

Highlights

Two-dimensional (2D) radiographs have been widely used in the field of orthodontics since 1922 [1]
Time-consuming, and financial challenges far associated with evaluations of the mandible, it is necessary to establish an efficient and precise mandibular segmentation protocol based on 3D cone-beam computed tomography (CBCT) that can (1) be performed with commonly used orthodontic imaging analysis software, (2) be easy to follow, (3) access the internal structures, and (4) allow novel 3D and traditional 2D superimpositions
Red arrows: buccally moved cortical plates. (G) Axial slice at the cervical level of the teeth. (H) Axial slice at the level of the deepest portion of the mandibular notch. For this short Communication article, our primary aim was to establish a simple protocol to segment the mandible from a full-volume craniofacial CBCT using the “Sculpting tool” provided with the Dolphin 3D Imaging software and to evaluate the precision and reliability of this protocol

Summary

Introduction

Two-dimensional (2D) radiographs have been widely used in the field of orthodontics since 1922 [1]. Since the software packages mentioned above are not designed for orthodontic applications, multiple software packages are generally necessary to analyze a single case This issue significantly increases the complexity of usage and financial input, as well as time and labor costs for the clinicians or orthodontic researchers for mandible-related evaluations and investigations. Time-consuming, and financial challenges far associated with evaluations of the mandible, it is necessary to establish an efficient and precise mandibular segmentation protocol based on 3D CBCT that can (1) be performed with commonly used orthodontic imaging analysis software, (2) be easy to follow (not technique-sensitive), (3) access the internal structures, and (4) allow novel 3D and traditional 2D superimpositions

Experimental Section

Findings

Discussion