Objectives: Three-dimensional models of mandibular condyles provide a way for condylar remodeling follow-up. The overall aim was to develop and validate a user-friendly workflow for cone beam CT (CBCT)-based semi-automatic condylar registration and segmentation.
Methods: A rigid voxel-based registration (VBR) technique for registration of two post-operative CBCT-scans was tested. Two modified mandibular rami, with or without gonial angle, were investigated as the volume of interest for registration. Inter- and intraoperator reproducibility of this technique was tested on 10 mandibular rami of orthognathic patients by means of intraclass correlation coefficients (ICC's) and descriptive statistics of the transformation values from the VBR. The difference in reproducibility between the two modified rami was evaluated using a paired -test ( < 0.05). For the segmentation, eight fresh frozen cadaver heads were scanned with CBCT and micro-CT. These data were used to test the inter- and intraoperator reproducibility (ICC's) and accuracy (Bland-Altman plot) of a newly designed workflow based on semi-automated contour enhancement.
Results: Excellent ICC's (0.94-0.99) were obtained for the voxel-based registration technique using both modified rami. If the gonial angle was not included in the volume of interest, there was a trend of increased operator error suggested by significant higher interoperator differences in translation values ( = 0,0036). The segmentation workflow proved to be highly reproducible with excellent ICC's (0.99), low absolute mean volume differences between operators (23.19 mm), within operators (28.93 mm) and low surface distances between models of different operators (<0.20 mm). Regarding the accuracy, CBCT-models slightly overestimate the condylar volume compared to micro-CT.
Conclusions: This study provides a validated user-friendly and reproducible method of creating three-dimensional-surface models of mandibular condyles out of longitudinal CBCT-scans.
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http://dx.doi.org/10.1259/dmfr.20190364 | DOI Listing |
Am J Orthod Dentofacial Orthop
December 2024
Discipline of Orthodontics, School of Dentistry, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia; Department of Orthodontics, Sydney Dental Hospital, Sydney Local Health District, Sydney, Australia; Division of Orthodontics, University Clinics of Dental Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland. Electronic address:
Introduction: The dentoskeletal effects of clear aligner treatment (CAT) with Invisalign vs temporary skeletal anchorage device-anchored Sydney intrusion spring (SIS) were compared in consecutively treated growing patients with anterior open bite using cone-beam computed tomography scans.
Methods: Fifteen adolescents treated exclusively with Invisalign, and 14 with SIS (first-phase treatment) were assessed retrospectively. Rigid-wise, voxel-based registration of pretreatment and posttreatment cone-beam computed tomography scans were performed using the anterior cranial base, maxillary plane, and mandibular body as reference regions.
CNS Neurosci Ther
December 2024
7T Magnetic Resonance Imaging Translational Medical Center, Department of Radiology, Southwest Hospital, Army Medical University (Third Military Medical University), Chongqing, China.
Aims: The aim of this study was to investigate the whole-brain asymmetry changes in spinocerebellar ataxia type 3 (SCA3) and their association with movement disorders.
Methods: Voxel-based morphometry (VBM) was used to assess asymmetry in gray matter (GM) volume in 83 genetically confirmed SCA3 patients and 83 sex- and age-matched healthy controls (HCs). The asymmetry index (AI) was analyzed for partial correlation with disease severity, as measured by the Scale for Assessment and Rating of Ataxia (SARA) and International Cooperative Ataxia Rating Scale (ICARS).
Front Aging Neurosci
December 2024
Department of Neurology, Affiliated Hospital of Xiangnan University, Chenzhou, China.
Background: Brain has been shown to undergo progressive atrophy in patients with Alzheimer's disease (AD); however, more evidence is needed to elucidate how the brain structure changes during the progression to AD. Here, we observed differences in the cerebral structure among patients with amnestic mild cognitive impairment (aMCI) and patients with AD.
Methods: A total of 46 participants were selected and divided into AD, aMCI, and healthy control (HC) groups.
Med Phys
November 2024
Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
Background: Voxel-based analysis (VBA) for population level radiotherapy (RT) outcomes modeling requires topology preserving inter-patient deformable image registration (DIR) that preserves tumors on moving images while avoiding unrealistic deformations due to tumors occurring on fixed images.
Purpose: We developed a tumor-aware recurrent registration (TRACER) deep learning (DL) method and evaluated its suitability for VBA.
Methods: TRACER consists of encoder layers implemented with stacked 3D convolutional long short term memory network (3D-CLSTM) followed by decoder and spatial transform layers to compute dense deformation vector field (DVF).
Med Phys
October 2024
The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, Guangdong Province, People's Republic of China.
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