Li Kuo Tan

Glaucoma severity affects diffusion tensor imaging (DTI) parameters of the optic nerve and optic radiation

OBJECTIVES To evaluate whether MR diffusion tensor imaging (DTI) of the optic nerve and optic radiation in glaucoma patients provides parameters to discriminate between mild and severe glaucoma and to determine whether DTI derived indices correlate with retinal nerve fibre layer (RNFL) thickness. METHODS 3-Tesla DTI was performed on 90 subjects (30 normal, 30 mild glaucoma and 30 severe glaucoma subjects) and the FA and MD of the optic nerve and optic radiation were measured. The categorisation into mild and severe glaucoma was done using the Hodapp-Parrish-Anderson (HPA) classification. RNFL thickness was also assessed on all subjects using OCT. Receiver operating characteristic (ROC) analysis and Spearmans correlation coefficient was carried out. RESULTS FA and MD values in the optic nerve and optic radiation decreased and increased respectively as the disease progressed. FA at the optic nerve had the highest sensitivity (87%) and specificity (80%). FA values displayed the strongest correlation with RNFL thickness in the optic nerve (r=0.684, p ≤ 0.001) while MD at the optic radiation showed the weakest correlation with RNFL thickness (r=-0.360, p ≤ 0.001). CONCLUSIONS The high sensitivity and specificity of DTI-derived FA values in the optic nerve and the strong correlation between DTI-FA and RNFL thickness suggest that these parameters could serve as indicators of disease severity.

Use of permeability surface area-product to differentiate intracranial tumours from abscess.

Background and Purpose Clinical and radiological findings of intracranial abscesses may mimic the findings of brain tumours and vice versa. However, the discrimination is of great clinical importance in planning treatment and in following prognosis and response to therapy. This study evaluates the Computed Tomography (CT) perfusion parameters, especially the permeability index, with the aim of evaluating the usefulness of dynamic CT perfusion imaging as an alternative tool to differentiate necrotic brain tumours and intracerebral abscesses. Materials and Methods A total of 21 patients underwent perfusion CT study and were divided into 2 groups: Group 1, patients with necrotic brain tumours (n=13); and Group 2, patients with cerebral abscesses (n=8). The mean perfusion parameters were obtained from the enhancing part of the lesion. The relative ratios were then calculated by using the results from mirrored regions within the contralateral hemisphere as reference. Results The results of this study showed that there was significant difference in the relative permeability surface values between necrotic brain tumours and cerebral abscesses (p=0.005). By applying the ROC curve, a value of 25.1 for rPS was found to be the best estimate to distinguish necrotic brain tumours from cerebral abscesses with a specificity of 88 % and sensitivity of 70 %. Conclusion CT perfusion, especially permeability surface, may allow for better differentiation of cerebral abscesses from brain tumours, making it a strong additional imaging modality in the early diagnosis of these two entities.

Riding on the crest of electronic publishing wave

When biij came into being in early 2005, it was envisioned as a tool for the dissemination of scientific knowledge. Today, biij continues to fulfill this role, having gone through a process of evolution and growth. In the early days [1], the email system was the main means of communication. All manuscript submissions, including its figures and images, were sent as email attachments to the managing editor. The subsequent reviewing stages were also done via email. To simplify the tracking process, the managing editor developed an in-house software to view and update the status of each of the submitted manuscripts. It was developed using the Active Server Pages (ASP) programming language and a Microsoft Access database, and is only viewable by the editors. Although the software served its purpose well, the journal has grown so much so that its requirements for additional features far outweigh the resources that were currently available. From January 2007, biij gradually implemented the open source Open Journal Systems (OJS) software for online manuscript submission, tracking and management. The software was developed as part of the Public Knowledge Project, managed in partnership between the Faculty of Education at the University of British Columbia, the Simon Fraser University Library, the School of Education at Stanford University, and the Canadian Centre for Studies in Publishing at Simon Fraser University [2]. From the outset of biijs birth, the publishers have always emphasised the searchability and availability of biij’s contents. In October 2005, biij became a member of CrossRef [3] and provided a unique Digital Object Identifier (DOI) for each of the published manuscripts, including the abstracts from selected meetings and conferences. This ensures that biij’s contents remain available in the future, even if there are changes to the structure of its website. Biij is now indexed in a number of indexing databases, including Scopus, Embase, and Compendex (since January 2008); Chemical Abstracts Service (CAS) (since April 2006); INSPEC (since March 2006); Index Copernicus International (since April 2006); Google Scholar (since December 2005); and Directory of Open Access Journals (DOAJ) (since September 2005). In November 2008, Elsevier also agreed to include all manuscripts prior to 2008 in its Scopus and EMBASE database. biij contents are currently being submitted to Pubmed Central [4], the online repository for biomedical and life sciences journal literature at the U.S. National Institutes of Health (NIH) [5]. This process is part of the requirements for the application of evaluation for the Pubmed/Medline database, to be initiated sometime in 2009.

Online Survey of Children's Understanding of Mobile Phones and EMF: Preliminary Results

An ongoing global online survey was initiated in October 2005 to compile and analyse information on the understanding of mobile phone technology and EMF among school children. Since November 2005 and till July 23, 2006, a total of 1,711 responses were recorded from 60 countries. The number of male respondents (n = 653, 38.2%) roughly equalled the female (n = 626, 36.6%), with an average age of 14.0 (plusmn2.8 SD) years. Almost 60% of the respondents do not own a mobile phone; and almost 60% of the respondents admitted that they did not know that mobile phones use EMF to function. Roughly two-thirds of the respondents also reported to not knowing that mobile phones can cause harmful effects. Out of those who believed so, a majority reported headache as the main problem

A low-cost, high-quality method for remote recording of presentations.

OBJECTIVE The purpose of this article was to develop a low-cost method for high-quality remote capturing and recording of multimedia presentations. CONCLUSION The method for making high-quality digital recordings of presentations by using the mix of freely available software presented in this article offers great potential for institutions on a budget as well as others seeking viable alternatives to current methods of presentation recording.

Neurometabolites Alteration in the Acute Phase of Mild Traumatic Brain Injury (mTBI): An In Vivo Proton Magnetic Resonance Spectroscopy (1H-MRS) Study

RATIONALE AND OBJECTIVES Magnetic resonance spectroscopy is a noninvasive imaging technique that allows for reliable assessment of microscopic changes in brain cytoarchitecture, neuronal injuries, and neurochemical changes resultant from traumatic insults. We aimed to evaluate the acute alteration of neurometabolites in complicated and uncomplicated mild traumatic brain injury (mTBI) patients in comparison to control subjects using proton magnetic resonance spectroscopy (1H magnetic resonance spectroscopy). MATERIAL AND METHODS Forty-eight subjects (23 complicated mTBI [cmTBI] patients, 12 uncomplicated mTBI [umTBI] patients, and 13 controls) underwent magnetic resonance imaging scan with additional single voxel spectroscopy sequence. Magnetic resonance imaging scans for patients were done at an average of 10 hours (standard deviation 4.26) post injury. The single voxel spectroscopy adjacent to side of injury and noninjury regions were analysed to obtain absolute concentrations and ratio relative to creatine of the neurometabolites. One-way analysis of variance was performed to compare neurometabolite concentrations of the three groups, and a correlation study was done between the neurometabolite concentration and Glasgow Coma Scale. RESULTS Significant difference was found in ratio of N-acetylaspartate to creatine (NAA/Cr + PCr) (χ2(2) = 0.22, P < .05) between the groups. The sum of NAA and N-acetylaspartylglutamate (NAAG) also shows significant differences in both the absolute concentration (NAA + NAAG) and ratio to creatine (NAA + NAAG/Cr + PCr) between groups (χ2(2) = 4.03, P < .05and (χ2(2) = 0.79, P < .05)). NAA values were lower in cmTBI and umTBI compared to control group. A moderate weak positive correlation were found between Glasgow Coma Scale with NAA/Cr + PCr (ρ = 0.36, P < .05 and NAA + NAAG/Cr + PCr (ρ = 0.45, P < .05)), whereas a moderate correlation was seen with NAA + NAAG (ρ = 0.38, P < .05). CONCLUSION Neurometabolite alterations were already apparent at onset of both complicated and uncomplicated traumatic brain injury. The ratio of NAA and NAAG has potential to serve as a biomarker reflecting injury severity in a quantifiable manner as it discriminates between the complicated and uncomplicated cases of mTBI.

Microstructural integrity of white matter tracts amongst older fallers: A DTI study

Objectives This study assesses the whole brain microstructural integrity of white matter tracts (WMT) among older individuals with a history of falls compared to non-fallers. Methods 85 participants (43 fallers, 42 non-fallers) were evaluated with conventional MRI and diffusion tensor imaging (DTI) sequences of the brain. DTI metrics were obtained from selected WMT using tract-based spatial statistics (TBSS) method. This was followed by binary logistic regression to investigate the clinical variables that could act as confounding elements on the outcomes. The TBSS analysis was then repeated, but this time including all significant predictor variables from the regression analysis as TBSS covariates. Results The mean diffusivity (MD) and axial diffusivity (AD) and to a lesser extent radial diffusivity (RD) values of the projection fibers and commissural bundles were significantly different in fallers (p < 0.05) compared to non-fallers. However, the final logistic regression model obtained showed that only functional reach, white matter lesion volume, hypertension and orthostatic hypotension demonstrated statistical significant differences between fallers and non-fallers. No significant differences were found in the DTI metrics when taking into account age and the four variables as covariates in the repeated analysis. Conclusion This DTI study of 85 subjects, do not support DTI metrics as a singular factor that contributes independently to the fall outcomes. Other clinical and imaging factors have to be taken into account.

TEMPORAL REGISTRATION OF RADIOFREQUENCY INFORMATION AND CT IMAGES FOR RADIOFREQUENCY ABLATION PROCEDURE

A computed tomography (CT) scanner is often used for visualization during the radiofrequency (RF) ablation (RFA) procedure. Temperatures at the ablation zone, power output, efficiency, and annotation are recorded once per second in the RF generator. Radiologists often review the RF and CT data post-operation for diagnostic and research purposes. However, they often rely on the CT data solely as it is difficult to relate the RF information to its CT counterpart. This paper describes the development of a graphical user interface application to co-register the CT images and the information from the RF generator temporally. Information from the RF generator, CT images during the RFA, and the pre-RFA CT images are displayed together. Users pinpoint a specific timestamp based on the RFA operation, and the corresponding CT images are retrieved and displayed.

Converting Data from the Lunar DPX-IQ Bone Densitometer for Interoperability

The Lunar DPX-IQ is a bone densitometer from the Lunar Corporation (now part of GE Healthcare), and was released around the year 1997. The main control system is built upon the MS-DOS operating system, and stores its data in a proprietary database and format. The system is not DICOM compatible, has no built-in computer networking functionality, and does not have any functionality to export its images or data to any standard format. With the ongoing consolidation and centralization of modality data, the Lunar DPX-IQ risks being prematurely retired from service due to its inoperability with other systems.

Web-Based Educational Portal on EMF for Children

The last decade has seen an unprecedented rise in the usage of mobile phone technology. This sudden technological shift has confused and concerned the general public over potential health risks due to electromagnetic field (EMF) radiation. This uncertainty is largely due to unfamiliarity with the technological concepts involved, and is best addressed via education. In this paper, we will introduce the efforts of the World Health Organization (WHO) and the University of Malaya, Malaysia, to design and implement a Web-based educational portal on EMF for children. This portal uses Macromediareg Flashreg, and utilizes multimedia and interactive exhibits as well as simple instructional language and concepts to introduce the curriculum