A Novel Region-Growing Based Semi-Automatic Segmentation Protocol for Three-Dimensional Condylar Reconstruction Using Cone Beam Computed Tomography (CBCT)

Objective

To present and validate a semi-automatic segmentation protocol to enable an accurate 3D reconstruction of the mandibular condyles using cone beam computed tomography (CBCT).

Materials and Methods

Approval from the regional medical ethics review board was obtained for this study. Bilateral mandibular condyles in ten CBCT datasets of patients were segmented using the currently proposed semi-automatic segmentation protocol. This segmentation protocol combined 3D region-growing and local thresholding algorithms. The segmentation of a total of twenty condyles was performed by two observers. The Dice-coefficient and distance map calculations were used to evaluate the accuracy and reproducibility of the segmented and 3D rendered condyles.

Results

The mean inter-observer Dice-coefficient was 0.98 (range [0.95–0.99]). An average 90^th percentile distance of 0.32 mm was found, indicating an excellent inter-observer similarity of the segmented and 3D rendered condyles. No systematic errors were observed in the currently proposed segmentation protocol.

Conclusion

The novel semi-automated segmentation protocol is an accurate and reproducible tool to segment and render condyles in 3D. The implementation of this protocol in the clinical practice allows the CBCT to be used as an imaging modality for the quantitative analysis of condylar morphology.     

Computer-Assisted Orthognathic Surgery for Patients with Cleft Lip/Palate: From Traditional Planning to Three-Dimensional Surgical Simulation

Background

Although conventional two-dimensional (2D) methods for orthognathic surgery planning are still popular, the use of three-dimensional (3D) simulation is steadily increasing. In facial asymmetry cases such as in cleft lip/palate patients, the additional information can dramatically improve planning accuracy and outcome. The purpose of this study is to investigate which parameters are changed most frequently in transferring a traditional 2D plan to 3D simulation, and what planning parameters can be better adjusted by this method.

Patients and Methods

This prospective study enrolled 30 consecutive patients with cleft lip and/or cleft palate (mean age 18.6±2.9 years, range 15 to 32 years). All patients received two-jaw single-splint orthognathic surgery. 2D orthodontic surgery plans were transferred into a 3D setting. Severe bony collisions in the ramus area after 2D plan transfer were noted. The position of the maxillo-mandibular complex was evaluated and eventually adjusted. Position changes of roll, midline, pitch, yaw, genioplasty and their frequency within the patient group were recorded as an alternation of the initial 2D plan. Patients were divided in groups of no change from the original 2D plan and changes in one, two, three and four of the aforementioned parameters as well as subgroups of unilateral, bilateral cleft lip/palate and isolated cleft palate cases. Postoperative OQLQ scores were obtained for 20 patients who finished orthodontic treatment.

Results

83.3% of 2D plans were modified, mostly concerning yaw (63.3%) and midline (36.7%) adjustments. Yaw adjustments had the highest mean values in total and in all subgroups. Severe bony collisions as a result of 2D planning were seen in 46.7% of patients. Possible asymmetry was regularly foreseen and corrected in the 3D simulation.

Conclusion

Based on our findings, 3D simulation renders important information for accurate planning in complex cleft lip/palate cases involving facial asymmetry that is regularly missed in conventional 2D planning.     

The Oropharyngeal Airway in Young Adults with Skeletal Class II and Class III Deformities: A 3-D Morphometric Analysis

Objectives

1) To determine the accuracy and reliability of an automated anthropometric measurement software for the oropharyngeal airway and 2) To compare the anthropometric dimensions of the oropharyngeal airway in skeletal class II and III deformity patients.

Methods

Cone-beam CT (CBCT) scans of 62 patients with skeletal class II or III deformities were used for this study. Volumetric, linear and surface area measurements retroglossal (RG) and retropalatal (RP) compartments of the oropharyngeal airway was measured with the 3dMDVultus software. Accuracy of automated anthropometric pharyngeal airway measurements was assessed using an airway phantom.

Results

The software was found to be reasonably accurate for measuring dimensions of air passages. The total oropharyngeal volume was significantly greater in the skeletal class III deformity group (16.7 ± 9.04 mm³) compared with class II subjects (11.87 ± 4.01 mm³). The average surface area of both the RG and RP compartments were significantly larger in the class III deformity group. The most constricted area in the RG and RP airway was significantly larger in individuals with skeletal class III deformity. The anterior-posterior (AP) length of this constriction was significantly greater in skeletal class III individuals in both compartments, whereas the width of the constriction was not significantly different between the two groups in both compartments. The RP compartment was larger but less uniform than the RG compartment in both skeletal deformities.

Conclusion

Significant differences were observed in morphological characteristics of the oropharyngeal airway in individuals with skeletal class II and III deformities. This information may be valuable for surgeons in orthognathic treatment planning, especially for mandibular setback surgery that might compromise the oropharyngeal patency.     

Three-Dimensional Evaluation of the Upper Airway Morphological Changes in Growing Patients with Skeletal Class III Malocclusion Treated by Protraction Headgear and Rapid Palatal Expansion: A Comparative Research

Objective

The aim of this study was to evaluate the morphological changes of upper airway after protraction headgear and rapid maxillary expansion (PE) treatment in growing patients with Class III malocclusion and maxillary skeletal deficiency compared with untreated Class III patients by cone-beam computed tomography (CBCT).

Methods

Thirty growing patients who have completed PE therapy were included in PE group. The control group (n = 30) was selected from the growing untreated patients with the same diagnosis. The CBCT scans of the pre-treatment (T1) and post-treatment (T2) of PE group and the control group were collected. Reconstruction and registration of the 3D models of T1 and T2 were completed. By comparing the data obtained from T1, T2 and control group, the morphological changes of the upper airway during the PE treatment were evaluated.

Results

Comparing with the data from T1 group, the subspinale (A) of maxilla and the upper incisor (UI) of the T2 group were moved in the anterior direction. The gnathion (Gn) of mandible was moved in the posterior-inferior direction. The displacement of the hyoid bone as well as the length and width of dental arch showed significant difference. The volume and mean cross-sectional area of nasopharynx, velopharynx and glossopharynx region showed significant difference. The largest anteroposterior/the largest lateral (AP/LR) ratios of the velopharynx and glossopharynx were increased, but the AP/LR ratio of the hypopharynx was decreased. In addition, the length and width of the maxillary dental arch, the displacement of the hyoid bone, the volume of nasopharynx and velopharynx, and the AP/LR ratio of the hypopharynx and velopharynx showed significant difference between the data from control and T2 group.

Conclusion

The PE treatment of Class Ⅲ malocclusion with maxillary skeletal hypoplasia leads to a significant increase in the volume of nasopharynx and velopharynx.     

Cone-Beam Computed Tomography Correlates with Conventional Helical Computed Tomography in Evaluation of Lipiodol Accumulation in HCC after Chemoembolization

Background & Aims

The amount of drug-loaded lipiodol in an HCC tumor post-transarterial chemoembolization (TACE) correlates with the risk of local tumor recurrence. Lipiodol enhancement of a tumor on conventional CT, measured in Hounsfield units (HU), can predict tumor response. Here we investigate whether cone-beam CT (CBCT) can also be used to predict tumor response, providing the benefit of being able to optimize the patient’s treatment plan intra-procedurally.

Methods

A total of 82 HCC nodules (82 patients), ≤5 cm in diameter, were treated with balloon-occluded TACE using miriplatin between December 2013 and November 2014. For each patient, both CBCT and conventional CT images were obtained post-TACE. The degree of correlation between CBCT and conventional CT was determined by comparing identical regions of interest for each imaging modality using pixel values.

Results

The pixel values from conventional CT and CBCT were highly correlated, with a Pearson correlation coefficient of 0.912 (p<0.001). The location of the nodules within the liver did not affect the results; the correlation coefficient was 0.891 (p<0.001) for the left lobe and 0.926 (p<0.001) for the right lobe. The mean pixel value for conventional CT was 439 ± 279 HU, and the mean pixel value for CBCT was 416 ± 311 HU.

Conclusions

CBCT may be used as a substitute for conventional CT to quantitatively evaluate the amount of drug-loaded lipiodol within an HCC nodule and, hence, the efficacy of TACE treatment. The major benefit of using CBCT is the ability to predict the likelihood of local recurrence intra-procedurally, enabling subsequent treatment optimization.     

How Accurate Are the Fusion of Cone-Beam CT and 3-D Stereophotographic Images?

Background

Cone-beam Computed Tomography (CBCT) and stereophotography are two of the latest imaging modalities available for three-dimensional (3-D) visualization of craniofacial structures. However, CBCT provides only limited information on surface texture. This can be overcome by combining the bone images derived from CBCT with 3-D photographs. The objectives of this study were 1) to evaluate the feasibility of integrating 3-D Photos and CBCT images 2) to assess degree of error that may occur during the above processes and 3) to identify facial regions that would be most appropriate for 3-D image registration.

Methodology

CBCT scans and stereophotographic images from 29 patients were used for this study. Two 3-D images corresponding to the skin and bone were extracted from the CBCT data. The 3-D photo was superimposed on the CBCT skin image using relatively immobile areas of the face as a reference. 3-D colour maps were used to assess the accuracy of superimposition were distance differences between the CBCT and 3-D photo were recorded as the signed average and the Root Mean Square (RMS) error.

Principal Findings:

The signed average and RMS of the distance differences between the registered surfaces were −0.018 (±0.129) mm and 0.739 (±0.239) mm respectively. The most errors were found in areas surrounding the lips and the eyes, while minimal errors were noted in the forehead, root of the nose and zygoma.

Conclusions

CBCT and 3-D photographic data can be successfully fused with minimal errors. When compared to RMS, the signed average was found to under-represent the registration error. The virtual 3-D composite craniofacial models permit concurrent assessment of bone and soft tissues during diagnosis and treatment planning.     

Three Dimensional Imaging of Paraffin Embedded Human Lung Tissue Samples by Micro-Computed Tomography

Background

Understanding the three-dimensional (3-D) micro-architecture of lung tissue can provide insights into the pathology of lung disease. Micro computed tomography (µCT) has previously been used to elucidate lung 3D histology and morphometry in fixed samples that have been stained with contrast agents or air inflated and dried. However, non-destructive microstructural 3D imaging of formalin-fixed paraffin embedded (FFPE) tissues would facilitate retrospective analysis of extensive tissue archives of lung FFPE lung samples with linked clinical data.

Methods

FFPE human lung tissue samples (n = 4) were scanned using a Nikon metrology µCT scanner. Semi-automatic techniques were used to segment the 3D structure of airways and blood vessels. Airspace size (mean linear intercept, Lm) was measured on µCT images and on matched histological sections from the same FFPE samples imaged by light microscopy to validate µCT imaging.

Results

The µCT imaging protocol provided contrast between tissue and paraffin in FFPE samples (15mm x 7mm). Resolution (voxel size 6.7 µm) in the reconstructed images was sufficient for semi-automatic image segmentation of airways and blood vessels as well as quantitative airspace analysis. The scans were also used to scout for regions of interest, enabling time-efficient preparation of conventional histological sections. The Lm measurements from µCT images were not significantly different to those from matched histological sections.

Conclusion

We demonstrated how non-destructive imaging of routinely prepared FFPE samples by laboratory µCT can be used to visualize and assess the 3D morphology of the lung including by morphometric analysis.     

Cone-Beam Computed Tomography Assessment of Lower Facial Asymmetry in Unilateral Cleft Lip and Palate and Non-Cleft Patients with Class III Skeletal Relationship

Introduction

To evaluate, using cone-beam computed tomography (CBCT), both the condylar-fossa relationships and the mandibular and condylar asymmetries between unilateral cleft lip and palate (UCLP) patients and non-cleft patients with class III skeletal relationship, and to investigate the factors of asymmetry contributing to chin deviation.

Methods

The UCLP and non-cleft groups consisted of 30 and 40 subjects, respectively, in mixed dentition with class III skeletal relationships. Condylar-fossa relationships and the dimensional and positional asymmetries of the condyles and mandibles were examined using CBCT. Intra-group differences were compared between two sides in both groups using a paired t-test. Furthermore, correlations between each measurement and chin deviation were assessed.

Results

It was observed that 90% of UCLP and 67.5% of non-cleft subjects had both condyles centered, and no significant asymmetry was found. The axial angle and the condylar center distances to the midsagittal plane were significantly greater on the cleft side than on the non-cleft side (P=0.001 and P=0.028, respectively) and were positively correlated with chin deviation in the UCLP group. Except for a larger gonial angle on the cleft side, the two groups presented with consistent asymmetries showing shorter mandibular bodies and total mandibular lengths on the cleft (deviated) side. The average chin deviation was 1.63 mm to the cleft side, and the average absolute chin deviation was significantly greater in the UCLP group than in the non-cleft group (P=0.037).

Conclusion

Compared with non-cleft subjects with similar class III skeletal relationships, the subjects with UCLP showed more severe lower facial asymmetry. The subjects with UCLP presented with more asymmetrical positions and rotations of the condyles on axial slices, which were positively correlated with chin deviation.     

Development of a Three-Dimensional Hand Model Using Three-Dimensional Stereophotogrammetry: Assessment of Image Reproducibility

Purpose

Using three-dimensional (3D) stereophotogrammetry precise images and reconstructions of the human body can be produced. Over the last few years, this technique is mainly being developed in the field of maxillofacial reconstructive surgery, creating fusion images with computed tomography (CT) data for precise planning and prediction of treatment outcome. Though, in hand surgery 3D stereophotogrammetry is not yet being used in clinical settings.

Methods

A total of 34 three-dimensional hand photographs were analyzed to investigate the reproducibility. For every individual, 3D photographs were captured at two different time points (baseline T0 and one week later T1). Using two different registration methods, the reproducibility of the methods was analyzed. Furthermore, the differences between 3D photos of men and women were compared in a distance map as a first clinical pilot testing our registration method.

Results

The absolute mean registration error for the complete hand was 1.46 mm. This reduced to an error of 0.56 mm isolating the region to the palm of the hand. When comparing hands of both sexes, it was seen that the male hand was larger (broader base and longer fingers) than the female hand.

Conclusions

This study shows that 3D stereophotogrammetry can produce reproducible images of the hand without harmful side effects for the patient, so proving to be a reliable method for soft tissue analysis. Its potential use in everyday practice of hand surgery needs to be further explored.     

Red Blood Cell Fatty Acids and Incident Diabetes Mellitus in the Women’s Health Initiative Memory Study

Context

The relations between dietary and/or circulating levels of fatty acids and the development of type 2 diabetes is unclear. Protective associations with the marine omega-3 fatty acids and linoleic acid, and with a marker of fatty acid desaturase activity delta-5 desaturase (D5D ratio) have been reported, as have adverse relations with saturated fatty acids and D6D ratio.

Objective

To determine the associations between red blood cell (RBC) fatty acid distributions and incident type 2 diabetes.

Design

Prospective observational cohort study nested in the Women’s Health Initiative Memory Study.

Setting

General population.

Subjects

Postmenopausal women.

Main Outcome Measures

Self-reported incident type 2 diabetes.

Results

There were 703 new cases of type 2 diabetes over 11 years of follow up among 6379 postmenopausal women. In the fully adjusted models, baseline RBC D5D ratio was inversely associated with incident type 2 diabetes [Hazard Ratio (HR) 0.88, 95% confidence interval (CI) 0.81–0.95) per 1 SD increase. Similarly, baseline RBC D6D ratio and palmitic acid were directly associated with incident type 2 diabetes (HR 1.14, 95% CI 1.04–1.25; and HR 1.24, 95% CI 1.14–1.35, respectively). None of these relations were materially altered by excluding incident cases in the first two years of follow-up. There were no significant relations with eicosapentaenoic, docosahexaenoic or linoleic acids.

Conclusions

Whether altered fatty acid desaturase activities or palmitic acid levels are causally related to the development of type 2 diabetes cannot be determined from this study, but our findings suggest that proportions of certain fatty acids in RBC membranes are associated with risk for type 2 diabetes.     

3D Reconstruction of Coronary Artery Vascular Smooth Muscle Cells

Aims

The 3D geometry of individual vascular smooth muscle cells (VSMCs), which are essential for understanding the mechanical function of blood vessels, are currently not available. This paper introduces a new 3D segmentation algorithm to determine VSMC morphology and orientation.

Methods and Results

A total of 112 VSMCs from six porcine coronary arteries were used in the analysis. A 3D semi-automatic segmentation method was developed to reconstruct individual VSMCs from cell clumps as well as to extract the 3D geometry of VSMCs. A new edge blocking model was introduced to recognize cell boundary while an edge growing was developed for optimal interpolation and edge verification. The proposed methods were designed based on Region of Interest (ROI) selected by user and interactive responses of limited key edges. Enhanced cell boundary features were used to construct the cell’s initial boundary for further edge growing. A unified framework of morphological parameters (dimensions and orientations) was proposed for the 3D volume data. Virtual phantom was designed to validate the tilt angle measurements, while other parameters extracted from 3D segmentations were compared with manual measurements to assess the accuracy of the algorithm. The length, width and thickness of VSMCs were 62.9±14.9μm, 4.6±0.6μm and 6.2±1.8μm (mean±SD). In longitudinal-circumferential plane of blood vessel, VSMCs align off the circumferential direction with two mean angles of -19.4±9.3° and 10.9±4.7°, while an out-of-plane angle (i.e., radial tilt angle) was found to be 8±7.6° with median as 5.7°.

Conclusions

A 3D segmentation algorithm was developed to reconstruct individual VSMCs of blood vessel walls based on optical image stacks. The results were validated by a virtual phantom and manual measurement. The obtained 3D geometries can be utilized in mathematical models and leads a better understanding of vascular mechanical properties and function.     

Comparison of the Accuracy of Voxel Based Registration and Surface Based Registration for 3D Assessment of Surgical Change following Orthognathic Surgery

Purpose

Superimposition of two dimensional preoperative and postoperative facial images, including radiographs and photographs, are used to evaluate the surgical changes after orthognathic surgery. Recently, three dimensional (3D) imaging has been introduced allowing more accurate analysis of surgical changes. Surface based registration and voxel based registration are commonly used methods for 3D superimposition. The aim of this study was to evaluate and compare the accuracy of the two methods.

Materials and methods

Pre-operative and 6 months post-operative cone beam CT scan (CBCT) images of 31 patients were randomly selected from the orthognathic patient database at the Dental Hospital and School, University of Glasgow, UK. Voxel based registration was performed on the DICOM images (Digital Imaging Communication in Medicine) using Maxilim software (Medicim-Medical Image Computing, Belgium). Surface based registration was performed on the soft and hard tissue 3D models using VRMesh (VirtualGrid, Bellevue City, WA). The accuracy of the superimposition was evaluated by measuring the mean value of the absolute distance between the two 3D image surfaces. The results were statistically analysed using a paired Student t-test, ANOVA with post-hoc Duncan test, a one sample t-test and Pearson correlation coefficient test.

Results

The results showed no significant statistical difference between the two superimposition methods (p<0.05). However surface based registration showed a high variability in the mean distances between the corresponding surfaces compared to voxel based registration, especially for soft tissue. Within each method there was a significant difference between superimposition of the soft and hard tissue models.

Conclusions

There were no significant statistical differences between the two registration methods and it was unlikely to have any clinical significance. Voxel based registration was associated with less variability. Registering on the soft tissue in isolation from the hard tissue may not be a true reflection of the surgical change.     

Intraocular Pressure Changes during Accommodation in Progressing Myopes,Stable Myopes and Emmetropes

Purpose

To investigate the changes of intraocular pressure (IOP) induced by 3-diopter (3 D) accommodation in progressing myopes, stable myopes and emmetropes.

Design

Cross-sectional study.

Participants

318 subjects including 270 myopes and 48 emmetropes.

Methods

195 progressing myopes, 75 stable myopes and 48 emmetropes participated in this study. All subjects had their IOP measured using iCare rebound tonometer while accommodative stimuli of 0 D and 3 D were presented.

Main Outcome Measures

IOP values without accommodation and with 3 D accommodation were measured in all subjects. Baseline IOPs and IOP changes were compared within and between groups.

Results

There was no significant difference in IOPs between progressing myopes, stable myopes and emmetropes when no accommodation was induced (17.47±3.46, 16.62±2.98 and 16.80±3.62 respectively, p>0.05). IOP experienced an insignificantly slight decrease after 3 D accommodation in three groups (mean change -0.19±2.16, -0.03±1.68 and -0.39±2.65 respectively, p>0.05). Subgroup analysis showed in progressing myopic group, IOP of children (<18 years old) declined with accommodation while IOP of adults (≥18 years) increased, and the difference was statistically significant (p = 0.008). However, after excluding the age factor, accommodation induced IOP changes of high progressing myopes (≤-6 D), low, moderate and non-myopes (>-6 D) was not significantly different after Bonferroni correction (p = 0.838).

Conclusions

Although no difference was detected between the baseline IOPs and accommodation induced IOP changes in progressing myopes, stable myopes and emmetropes, this study found accommodation could cause transient IOP elevation in adult progressing myopes.     

Clinical Features and Treatment Modes of Mandibular Fracture at the Department of Oral and Maxillofacial Surgery,Shimane University Hospital,Japan

Background

The number of elderly patients with maxillofacial trauma is rapidly increasing due to active lifestyles and longevity. Shimane prefecture has the fastest growing proportion of elderly individuals in Japan. The aim of this study was to reveal the distinctive features and treatment modes of mandibular fracture treatment mode in patients requiring hospitalization at the Department of Oral and Maxillofacial Surgery, Shimane University Hospital, Japan.

Patients and Methods

Patient age, sex, period between injury and first consultation, years since injury, cause of injury, fracture site, treatment, and duration of hospitalization were evaluated. Univariate Poisson regression, relative risk with 95% confidence interval based on the Wald test, Fisher’s exact test, and Kruskal-Wallis test were used to explore associations among clinical and demographic variables.

Results

In total, 305 patients were diagnosed with and hospitalized for mandibular fracture from 1980 to 2010. Younger age increased the risk for mandibular fracture. Incidence was higher in males than females, particularly in the young, but the male to female ratio decreased with age. The period until first hospital consultation decreased progressively over the study period. Fall was a much more frequent cause in patients aged ≥60 than in those aged <60 years. Mandibular fracture with condyle, symphysis, and angle involvement were most common and were associated with sex, age, and treatment mode. Length of hospitalization has decreased since 1980.

Conclusion

In our department, patients aged ≥60 years accounted for a greater proportion of mandibular fracture cases than in many previous studies, reflecting the greater proportion of elderly residents in Shimane prefecture.     

Virtual Training of the Myosignal

Objective

To investigate which of three virtual training methods produces the largest learning effects on discrete and continuous myocontrol. The secondary objective was to examine the relation between myocontrol and manual motor control tests.

Design

A cohort analytic study.

Setting

University laboratory.

Participants

3 groups of 12 able-bodied participants (N = 36).

Interventions

Participants trained the control over their myosignals on 3 consecutive days. Training was done with either myosignal feedback on a computer screen, a virtual myoelectric prosthetic hand or a computer game. Participants performed 2 myocontrol tests and 2 manual motor control tests before the first and after the last training session. They were asked to open and close a virtual prosthetic hand on 3 different velocities as a discrete myocontrol test and followed a line with their myosignals for 30 seconds as a continuous myocontrol test. The motor control tests were a pegboard and grip-force test.

Main Outcome Measures

Discrete myocontrol test: mean velocities. Continuous myocontrol test: error and error SD. Pegboard test: time to complete. Grip-force test: produced forces.

Results

No differences in learning effects on myocontrol were found for the different virtual training methods. Discrete myocontrol ability did not significantly improve as a result of training. Continuous myocontrol ability improved significantly as a result of training, both on average control and variability. All correlations between the motor control and myocontrol test outcome measures were below .50.

Conclusions

Three different virtual training methods showed comparable results when learning myocontrol. Continuous myocontrol was improved by training while discrete myocontrol was not. Myocontrol ability could not be predicted by the manual motor control tests.     

A Method of Three-Dimensional Recording of Mandibular Movement Based on Two-Dimensional Image Feature Extraction

Background and Objective

To develop a real-time recording system based on computer binocular vision and two-dimensional image feature extraction to accurately record mandibular movement in three dimensions.

Methods

A computer-based binocular vision device with two digital cameras was used in conjunction with a fixed head retention bracket to track occlusal movement. Software was developed for extracting target spatial coordinates in real time based on two-dimensional image feature recognition. A plaster model of a subject’s upper and lower dentition were made using conventional methods. A mandibular occlusal splint was made on the plaster model, and then the occlusal surface was removed. Temporal denture base resin was used to make a 3-cm handle extending outside the mouth connecting the anterior labial surface of the occlusal splint with a detection target with intersecting lines designed for spatial coordinate extraction. The subject''s head was firmly fixed in place, and the occlusal splint was fully seated on the mandibular dentition. The subject was then asked to make various mouth movements while the mandibular movement target locus point set was recorded. Comparisons between the coordinate values and the actual values of the 30 intersections on the detection target were then analyzed using paired t-tests.

Results

The three-dimensional trajectory curve shapes of the mandibular movements were consistent with the respective subject movements. Mean XYZ coordinate values and paired t-test results were as follows: X axis: -0.0037 ± 0.02953, P = 0.502; Y axis: 0.0037 ± 0.05242, P = 0.704; and Z axis: 0.0007 ± 0.06040, P = 0.952. The t-test result showed that the coordinate values of the 30 cross points were considered statistically no significant. (P<0.05)

Conclusions

Use of a real-time recording system of three-dimensional mandibular movement based on computer binocular vision and two-dimensional image feature recognition technology produced a recording accuracy of approximately ± 0.1 mm, and is therefore suitable for clinical application. Certainly, further research is necessary to confirm the clinical applications of the method.     

Three dimensional assessment of the pharyngeal airway in individuals with non-syndromic cleft lip and palate

Introduction

Children with cleft lip and palate (CLP) are known to have airway problems. Previous studies have shown that individuals with CLP have a 30% reduction in nasal airway size compared to non-cleft controls. No reports have been found on cross-sectional area and volume of the pharyngeal airway in clefts. Introduction of Cone-Beam CT (CBCT) and imaging software has facilitated generation of 3D images for assessment of the cross-sectional area and volume of the airway.

Objective

To assess the pharyngeal airway in individuals with CLP using CBCT by measuring volume and smallest cross-sectional areas and compare with 19 age- and sex-matched non-cleft controls.

Methods

Retrospective study of CBCT data of pre-adolescent individuals (N = 19, Mean age = 10.6, 7 females, 12 males, UCLP = 6, BCLP = 3) from the Center for Craniofacial Anomalies. Volumetric analysis was performed using image segmentation features in CB Works 3.0. Volume and smallest cross-sectional were studied in both groups. Seven measurements were repeated to verify reliability using Pearson correlation coefficient. Volume and cross-sectional area differences were analyzed using paired t-tests.

Results

The method was found to be reliable. Individuals with CLP did not exhibit smaller total airway volume and cross sectional area than non-CLP controls.

Conclusion

3D imaging using CBCT and CB Works is reliable for assessing airway volume. Previous studies have shown that the nasal airway is restricted in individuals with CLP. In our study, we found that the pharyngeal airway is not compromised in these individuals.     

The Repeatability Assessment of Three-Dimensional Capsule-Intraocular Lens Complex Measurements by Means of High-Speed Swept-Source Optical Coherence Tomography

Purpose

To rebuild the three-dimensional (3-D) model of the anterior segment by high-speed swept-source optical coherence tomography (SSOCT) and evaluate the repeatability of measurement for the parameters of capsule-intraocular lens (C-IOL) complex.

Methods

Twenty-two pseudophakic eyes from 22 patients were enrolled. Three continuous SSOCT measurements were performed in all eyes and the tomograms obtained were used for 3-D reconstruction. The output data were used to evaluate the measurement repeatability. The parameters included postoperative aqueous depth (PAD), the area and diameter of the anterior capsule opening (Area and D), IOL tilt (IOL-T), horizontal, vertical, and space decentration of the IOL, anterior capsule opening, and IOL-anterior capsule opening.

Results

PAD, IOL-T, Area, D, and all decentration measurements showed high repeatability. Repeated measure analysis showed there was no statistically significant difference among the three continuous measurements (all P > .05). Pearson correlation analysis showed high correlation between each pair of them (all r >0.90, P<0.001). ICCs were all more than 0.9 for all parameters. The 95% LoAs of all parameters were narrow for comparison of three measurements, which showed high repeatability for three measurements.

Conclusion

SSOCT is available to be a new method for the 3-D measurement of C-IOL complex after cataract surgery. This method presented high repeatability in measuring the parameters of the C-IOL complex.     

Cephalometric Analysis of the Facial Skeletal Morphology of Female Patients Exhibiting Skeletal Class II Deformity with and without Temporomandibular Joint Osteoarthrosis

Purpose

This study evaluated the differences in the facial morphological characteristics of female patients exhibiting skeletal class II deformity with and without temporomandibular joint osteoarthrosis.

Methods

Eighty-three female patients with skeletal class II deformity were included in this study; these patients were classified into three groups on the basis of the condylar features shown in cone-beam computed tomography scans: normal group, indeterminate for osteoarthrosis group, and osteoarthrosis group. The cephalometric differences among the three groups were evaluated through one-way ANOVA.

Results

Of the 83 patients, 52.4% were diagnosed with osteoarthrosis, as indicated by the changes in the condylar osseous component. The cephalometric measurements that represented skeletal characteristics, including mandibular position relative to the cranial base, mandibular plane angle (MP-SN), posterior facial height (S-Go), and facial height ratio, were significantly different among the three groups (p < 0.05). The patients in the osteoarthrosis group yielded the smallest S-Go, the highest MP-SN, and the most retruded mandible.

Conclusions

Temporomandibular joint osteoarthrosis is commonly observed in female patients with skeletal class II deformity. The morphological characteristics of the facial skeleton in patients with bilateral condylar osteoarthrosis may be altered.     

Analysis of Prostate Deformation during a Course of Radiation Therapy for Prostate Cancer

Purpose

Accurate analysis of the correlation between deformation of the prostate and displacement of its center of gravity (CoG) is important for efficient radiation therapy for prostate cancer. In this study, we addressed this problem by introducing a new analysis approach.

Method

A planning computed tomography (CT) scan and 7 repeat cone-beam CT scans during the course of treatment were obtained for 19 prostate cancer patients who underwent three-dimensional conformal radiation therapy. A single observer contoured the prostate gland only. To evaluate the local deformation of the prostate, it was divided into 12 manually defined segments. Prostate deformation was calculated using in-house developed software. The correlation between the displacement of the CoG and the local deformation of the prostate was evaluated using multiple regression analysis.

Results

The mean value and standard deviation (SD) of the prostate deformation were 0.6 mm and 1.7 mm, respectively. For the majority of the patients, the local SD of the deformation was slightly lager in the superior and inferior segments. Multiple regression analysis revealed that the anterior-posterior displacement of the CoG of the prostate had a highly significant correlation with the deformations in the middle-anterior (p < 0.01) and middle-posterior (p < 0.01) segments of the prostate surface (R² = 0.84). However, there was no significant correlation between the displacement of the CoG and the deformation of the prostate surface in other segments.

Conclusion

Anterior-posterior displacement of the CoG of the prostate is highly correlated with deformation in its middle-anterior and posterior segments. In the radiation therapy for prostate cancer, it is necessary to optimize the internal margin for every position of the prostate measured using image-guided radiation therapy.