ORCID Profile
0000-0003-3369-243X
Current Organisation
University of South Australia
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: British Institute of Radiology
Date: 05-2006
Abstract: To assess the effect of a laser-guided collimator in intraoral radiography training. A custom-made collimator with four red laser diodes on each corner on the rim of an aluminium alloy cubic housing was fabricated. The laser used low power diodes, which are classified as laser-safe by the United States Food and Drug Administration (FDA). When activated, the effective dimensions of the laser beams were 4 cm x 4.5 cm. Eighteen dental hygiene students were randomized into test and control groups. The Laser group used a rectangular collimator with the laser device, while the Non-laser group used a conventional rectangular collimator. Each group attended nine intraoral radiography training sessions. All radiographs were assessed and were classified into three categories: Excellent, Acceptable and Repeat, by a masked academic staff member. Reasons for repeats were marked. Statistical comparisons between the two groups were made. A total of 2334 radiographs were made. Conecut was more common on bitewings than periapicals. The Laser group produced fewer conecuts than the Non-laser group. The Laser group produced more excellent radiographs with fewer repeats than the Non-laser group, but there was not a significant difference. The laser-guided collimator helped the students to produce fewer repeats in a shorter period of time. It was an effective training aid.
Publisher: MDPI AG
Date: 31-03-2022
DOI: 10.3390/LIFE12040514
Abstract: This study aimed to build automated detection models—one by brain regional volume (V-model), and the other by radiomics features of the whole brain (R-model)—to differentiate mild cognitive impairment (MCI) from cognitive normal (CN), and Alzheimer’s Disease (AD) from mild cognitive impairment (MCI). The objectives are to compare the models and identify whether radiomics or volumetry can provide a better prediction for differentiating different types of dementia. Method: 582 MRI T1-weighted images were retrieved from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database, which is a multicenter operating open source database for AD. In total, 97 images of AD, 293 images of MCI patient and 192 images of cognitive normal were ided into a training, a validation and a test group at a ratio of 70:15:15. For each T1-weighted image, volumetric segmentation was performed with the image analysis software FreeSurfer, and radiomics features were retrieved by imaging research software 3D slicers. Brain regional volume and radiomics features were used to build the V-model and R-model, respectively, using the random forest algorithm by R. The receiver operating characteristics (ROC) curve of both models were used to evaluate their diagnostic accuracy and reliability to differentiate AD, MCI and CN. Results: To differentiate MCI and CN, both V-model and R-model achieved excellent performance, with an AUC of 0.9992 ± 0.0022 and 0.9850 ± 0.0032, respectively. No significant difference was found between the two AUCs, indicating both models attained similar good performance. In MCI and AD differentiation, the V-model and R-model yielded AUC of 0.9986 ± 0.0013 and 0.9714 ± 0.0175, respectively. The best performance was to differentiate AD from CN, where the V-model and R-model yielded AUC of 0.9994 ± 0.0019 and 0.9830 ± 0.009, respectively. The results suggested that both volumetry and radiomics approaches could be used in differentiating AD, MCI and CN, based on T1 weighted MR images using random forest algorithm successfully. Conclusion: This study showed that the radiomics features from T1-weighted MR images achieved excellence performance in differentiating AD, MCI and CN. Compared to the volumetry method, the accuracy, sensitivity and specificity are slightly lower in using radiomics, but still attained very good and reliable classification of the three stages of neurodegenerations. In view of the convenience and operator independence in feature extraction, radiomics can be a quantitative biomarker to differentiate the disease groups.
Publisher: Bentham Science Publishers Ltd.
Date: 02-2010
Publisher: Elsevier BV
Date: 2020
Publisher: Medical Association of Pharmacopuncture Institute
Date: 03-2010
Publisher: Wiley
Date: 13-04-2011
DOI: 10.1111/J.1600-0501.2011.02188.X
Abstract: Conebeam computed tomography (CBCT) and magnetic resonance imaging (MRI) have been used to identify the mandibular nerve but a comparison of the reliabilities of the two imaging modalities has not been performed. It was hypothesized that the reliabilities were not different between the two. Twelve dental postgraduates in five disciplines were recruited to assess two sets of reformatted oblique images (CBCT and MRI) of 11 patients who were scanned before wisdom teeth extraction. The variance of the identified locations of mandibular nerve, the mental foramen and the mandibular foramen between two sets of images of each patient was compared. Each set of images was rated by assessors to reveal the satisfaction in determining the structures. It was found that by using MRI images, significantly lesser variances and significantly higher satisfactory scores were given by the assessors than by using CBCT images in the identification of the structures. We concluded that MRI is a promising imaging modality that can be used to identify the mandibular nerve when it cannot be found in CBCT images.
Publisher: Elsevier BV
Date: 02-2005
Publisher: Wiley
Date: 16-08-2004
Publisher: Bentham Science Publishers Ltd.
Date: 12-2009
Publisher: MDPI AG
Date: 19-09-2022
DOI: 10.3390/BIOMEDICINES10092321
Abstract: Introduction: Amyloid-β protein (Aβ) is one of the biomarkers for Alzheimer’s disease (AD). The recent application of interhemispheric functional connectivity (IFC) in resting-state fMRI has been used as a non-invasive diagnostic tool for early dementia. In this study, we focused on the level of Aβ accumulated and its effects on the major functional networks, including default mode network (DMN), central executive network (CEN), salience network (SN), self-referential network (SRN) and sensory motor network (SMN). Methods: 58 participants (27 Hi Aβ (HiAmy) and 31 low Aβ (LowAmy)) and 25 healthy controls (HC) were recruited. [18F]flutemetamol PET/CT was performed for diseased groups, and MRI scanning was done for all participants. Voxel-by-voxel correlation analysis was done for both groups in all networks. Results: In HiAmy, IFC was reduced in all networks except SN. A negative correlation in DMN, CEN, SRN and SMN suggests high Aβ related to IFC reduction However, a positive correlation in SN suggests high Aβ related to an increase in IFC. In LowAmy, IFC increased in CEN, SMN, SN and SRN. Positive correlation in all major brain networks. Conclusion: The level of Aβ accumulated demonstrated differential effects on IFC in various brain networks. As the treatment to reduce Aβ plaque deposition is available in the market, it may be an option for the HiAmy group to improve their IFC in major brain networks.
Publisher: Frontiers Media SA
Date: 14-07-2022
DOI: 10.3389/FNEUR.2022.869248
Abstract: Approximately one-third of stroke survivors experience post-stroke depression. Repetitive transcranial magnetic stimulation (rTMS) of the prefrontal cortex has shown promise as a treatment for depression with few side effects and high tolerability. However, previous post-stroke depression trials have not considered the effect of lesion location, the persistence of clinical improvements, nor the value of ongoing maintenance treatments. These questions are important to determine the therapeutic value of rTMS as a treatment for post-stroke depression. We report a unique case study of a 71-year-old male who had experienced a left hemispheric ischemic stroke 4 years prior. The patient was screened with the Beck Depression Inventory and Patient Health Questionnaire and found to be experiencing moderate levels of depression. Ten daily sessions of left dorsolateral pre-frontal cortex rTMS were applied over a two-week period. A clinically meaningful reduction in depression was achieved. Approximately 10 weeks following rTMS treatment, improvements in depression were attenuating. Weekly maintenance rTMS was delivered to the left dorsolateral pre-frontal cortex for 10 sessions. At the conclusion of maintenance rTMS, clinical assessments indicated depressive symptoms had reduced to a minimal to nil level. Clinically meaningful improvements in depression were maintained at 3 months after rTMS treatment had ceased. These findings provide novel insight to suggest rTMS may reduce depressive symptoms in stroke survivors with a lesion at the site of stimulation. Ongoing maintenance treatments might prove beneficial to enhance persistence of clinical improvements.
Publisher: Springer Netherlands
Date: 11-11-2012
Publisher: Wiley
Date: 22-12-2003
DOI: 10.1046/J.1475-1313.2003.00159.X
Abstract: The purpose of this study is to determine if there is an association between eye size and the volume of the orbit in adult subjects. Thirty-three subjects with varying degrees of ametropia (+1.00 to -12.75 D) underwent magnetic resonance scan of the orbit. Results show that the larger myopic eye was not associated with a larger orbit.
Publisher: Wiley
Date: 07-01-2013
DOI: 10.1111/CLR.12096
Abstract: The width of the facial alveolar bone wall is crucial for long-term successful esthetic outcomes of implants immediately placed into extraction sockets. A threshold of 2 mm is recommended to minimize buccal vertical bone resorption. To assess the width of the facial alveolar bone wall using cone-beam computed tomography images (CBCT). Retrospective CBCT images were acquired from a representative s le of Asians using the i-CAT classic system with a 0.4-mm voxel size. At random, 200 CBCT images were selected according to predefined criteria. The DICOM file was imported into the i-CAT Vision software. In the panoramic screen, the middle of each tooth was selected, and in the sagittal window, the middle cross section was selected for performing the measurements using a computer. The vertical distance from the alveolar crest (BC) - cemento-enamel junction (CEJ) was measured. The width of the facial alveolar bone wall was measured at three locations: 1, 3, and 5 mm apical to BC. Descriptive statistics, frequency analyses, and multi-level comparisons were performed. The s le consisted of 74 men and 126 women (mean age of 37.2 years range 17-82 years). A total of 3618 teeth were assessed. There was no significant difference between the values of right and left sides, or between genders. However, statistically significant differences were observed between age groups at all levels. The distance from CEJ to BC varied from 0.4 to 4 mm, with an overall tendency to increase with age. The mean width of the facial alveolar bone wall at anterior teeth was 0.9 mm and increased toward posterior regions. Rarely, a width of 2 mm was yielded (0.6-1.8% for anterior teeth, 0.7-30.8% for posterior teeth). At a 5-mm distance from BC, minimal widths of facial alveolar bone were identified for the anterior teeth. The frequency of dehiscence ranged from 9.9% to 51.6% for anterior and 3.1% to 53.6% for posterior teeth, respectively. A thin facial alveolar bone wall was usually present in both jaws. Hence, for most patients, adjunctive bone augmentation may be needed when installing implants in areas of esthetic concern.
Publisher: Mary Ann Liebert Inc
Date: 12-2009
Publisher: Elsevier BV
Date: 04-2022
DOI: 10.1016/J.YFRNE.2021.100970
Abstract: Resting-state functional magnetic resonance imaging (rs-fMRI) has been actively used in the last decade to investigate brain functional connectivity alterations in Type 2 Diabetes Mellitus (T2DM) to understand the neuropathophysiology of T2DM in cognitive degeneration. Given the emergence of new analysis techniques, this scoping review aims to map the rs-fMRI analysis techniques that have been applied in the literature and reports the latest rs-fMRI findings that have not been covered in previous reviews. Graph theory, the contemporary rs-fMRI analysis, has been used to demonstrate altered brain topological organisations in people with T2DM, which included altered degree centrality, functional connectivity strength, the small-world architecture and network-based statistics. These alterations were correlated with T2DM patients' cognitive performances. Graph theory also contributes to identify unbiased seeds for seed-based analysis. The expanding rs-fMRI analytical approaches continue to provide new evidence that helps to understand the mechanisms of T2DM-related cognitive degeneration.
Publisher: Wiley
Date: 04-12-2014
DOI: 10.1111/CLR.12292
Abstract: To study residual ridge dimensions at edentulous first molar sites in relation to periodontal bone loss among cohorts of partially edentulous Asian Indian and Hong Kong Chinese subjects seeking tooth replacement. A total of 628 edentulous maxillary first molar sites were analyzed on Cone Beam Computed Tomography scans of 225 Asian Indian (I) and 232 Hong Kong Chinese (C) partially edentulous adults seeking tooth replacement. Age, ethnicity, gender, total tooth loss, the presence or absence of adjacent teeth, categories of periodontal status defined according to radiographic alveolar bone loss (P0: periodontal health, P1: incipient to moderate disease, P2: severe periodontal disease) and sinus membrane abnormalities were noted. Alveolar ridge height (RH), widths at 1 and 3 mm from crest (RW1 RW3), and relative position of the bone crest (RR) were measured. Prevalence of P2 status was most frequent in both cohorts(C: 50.4% I: 49.2%). P2 had lowest ridge heights 13.1% C P2 and 14%I P2 had RH < 2 mm. Sites with both RH <8 mm and RW1 < 6 mm occurred at 59%C P2 and 68%I P2. Sinus membrane abnormalities were most frequent in P2. Periodontal status and sinus membrane abnormality increased the odds of RH <5 mm and RH <8 mm more than 2-fold additionally, gender and ethnicity significantly impacted RH <8 mm. Gender and adjacent tooth status significantly affected RW1. Incident advanced periodontal disease was common among Asian Indian and Hong Kong Chinese subjects seeking tooth replacement and associated with lower available bone heights. Ethnicity, gender, sinus membrane thickening affected available bone height in the subsinus region, while the presence of adjacent teeth- and age-affected residual ridge width.
Publisher: Springer Science and Business Media LLC
Date: 12-12-2019
DOI: 10.1007/S10103-019-02923-0
Abstract: Low-level laser irradiation (LLLI) shows effects in orthodontic pain relief and periodontal inflammation control. The aim of this article is to investigate the analgesic and inflammation-modulatory effects of low-level laser irradiation among orthodontic patients with compromised periodontium. A randomised controlled trial with split-mouth design was conducted in 27 adults with treated and controlled chronic periodontitis over 6 months. One side of the dental arch underwent repeated treatment under a 940-nm diode laser (EZlase Biolase Technology Inc.) with a beam size of 2.8 cm 2 for 60 seconds at 8.6 J/cm 2 , whilst the other side received pseudo-laser treatment. Laser irradiation was applied repeatedly for 8 times during the first 6 weeks after bracket bonding and monthly thereafter until the end of orthodontic treatment. Subjective pain (assessed by visual analogue scale in pain diary and by chairside archwire activation), periodontal status (assessed by periodontal clinical parameters), cytokines in gingival crevicular fluid (interleukin 1β, prostaglandin E 2 , substance P) and periodontopathic bacteria ( Porphyromonas gingivalis and Treponema denticola ) in supragingival plaque were assessed. The intensity of pain was lower on the laser-irradiated side at multiple follow-up visits (P 0.05). The pain subsided 1 day earlier on the laser side, with a lower peak value during the first week after initial archwire placement (P 0.05). The laser side exhibited a smaller reduction in bite force during the first month (mean difference = 3.17, 95% CI: 2.36–3.98, P 0.05 at 1-week interval mean difference = 3.09, 95% CI: 1.87–4.32, P 0.05 at 1-month interval). A smaller increase was observed in the plaque index scores on the laser side at 1-month (mean difference = 0.19, 95% CI: 0.13–0.24, P 0.05) and in the gingival index scores at the 3-month follow-up visit (mean difference = 0.18, 95% CI: 0.14–0.21, P 0.05). Laser irradiation inhibited the elevation of interleukin-1β, prostaglandin E 2 and substance P levels during the first month (P 0.05). However, no intergroup difference was detected in the bacteria levels. Low-level laser irradiation exhibits benefits in pain relief and inflammation control during the early stage of adjunctive orthodontic treatment in periodontally compromised in iduals.
Publisher: Elsevier BV
Date: 04-2009
DOI: 10.1016/J.TRIPLEO.2008.11.009
Abstract: The objective of this study was to compare typical patient radiation dose delivered in implant imaging with spiral computed tomography (CT), conventional spiral tomography, and cone-beam CT (CBCT). The Scanora (Orion Corporation Soredex, Helsinki, Finland), Spiral HiSpeed/Fxi (General Electric, Milwaukee, WI), and Classic iCAT (Imaging Sciences International, Hatfield, PA) units were selected to represent conventional spiral tomography, spiral CT, and CBCT, respectively. Thermoluminescent dosimeters were used in a Rando phantom to measure radiation-absorbed doses to the lenses, parotid glands, submandibular glands, sublingual gland, and the thyroid for maxillary and mandibular implant imaging techniques. Spiral CT delivered the highest absorbed dose, whereas CBCT delivered the lowest in both maxillary and mandibular implant scans. The salivary glands received the highest absorbed doses. Scanora delivered lower radiation doses than CBCT when the anterior region of the maxilla or mandible was irradiated. In implant imaging, CT delivers the highest radiation dose to the salivary glands, whereas the CBCT system studied delivers the lowest dose. Irrespective of imaging modality, during implant imaging as conducted for this study, salivary glands receive most radiation.
Publisher: Quintessence Publishing
Date: 05-2014
DOI: 10.11607/JOMI.3354
Abstract: The study evaluated the diagnostic performance of computed tomography (CT) bone density measurements (in Hounsfield units [HU]) in assessing the osteoporotic status of edentulous subjects (21 men, 40 women) scheduled to receive mandibular implant-supported overdentures. Density (in HU) of 61 left and 61 right mandibular canine sites was measured. Each subject was also subject to body bone mineral density measurements (dual-energy x-ray absorptiometry). Bone density T-score values of total hip, femoral neck, spine (L1 to L4), and total body were assessed. Pearson correlations were conducted between HU of each mandibular bone site and the subject's T-score values. Sensitivity/specificity and receiver operating characteristic curve analyses were used to assess the diagnostic performance of HU in detecting subjects who were, based on each of the four T-scores: (1) "not osteonormal", ie, with a T-score at or below -1.0 or (2) osteoporotic, ie, with a T-score at or below -2.5. HU measurements of mandibular bone sites were found to have modest but significant correlations with each bone density T-score value (total hip, femoral neck, spine, total body). CT mandibular site HU measurement has diagnostic value in detecting a "not osteonormal" condition when total hip, spine, or total body T-scores were used, but not when femoral neck T-score was used. Based on the limited s le size, optimal HU cutoff values of ~530, ~600, and ~640 HU for total hip, spine, or total body T-scores, respectively, were proposed. CT mandibular site HU measurement had diagnostic value in detecting osteoporosis when spine T-score was used but not when total hip, femoral neck, and total body T-scores were used. An optimal HU cutoff value of ~460 HU for spine T-score was proposed.
Publisher: Elsevier BV
Date: 03-2016
DOI: 10.1016/J.CRAD.2015.11.020
Abstract: To determine the most robust commonly available magnetic resonance imaging (MRI) sequence to quantify breast tissue composition at 1.5 T. Two-dimensional (2D) T1-weighted, Dixon fat, Dixon water and SPAIR images were obtained from five participants and a breast phantom using a 1.5 T Siemens Aera MRI system. Manual segmentation of the breasts was performed, and an in-house computer program was used to generate signal intensity histograms. Relative trough depth and relative peak separation were used to determine the robustness of the images for quantifying the two breast tissues. Total breast volumes and percentage breast densities calculated using the four sequences were compared. Dixon fat histograms had consistently low relative trough depth and relative peak separation compared to those obtained using other sequences. There was no significant difference in total breast volumes and percentage breast densities of the participants or breast phantom using Dixon fat and 2D T1-weighted histograms. Dixon water and SPAIR histograms were not suitable for quantifying breast tissue composition. Dixon fat images are the most robust for the quantification of breast tissue composition using a signal intensity histogram.
No related grants have been discovered for Anson CM Chau.