A novel phantom and method for comprehensive 3-dimensional measurement and correction of geometric distortion in magnetic resonance imaging

A phantom that can be used for mapping geometric distortion in magnetic resonance imaging (MRI) is described. This phantom provides an array of densely distributed control points in three-dimensional (3D) space. These points form the basis of a comprehensive measurement method to correct for geometric distortion in MR images arising principally from gradient field non-linearity and magnet field inhomogeneity. The phantom was designed based on the concept that a point in space can be defined using three orthogonal planes. This novel design approach allows for as many control points as desired. Employing this novel design, a highly accurate method has been developed that enables the positions of the control points to be measured to sub-voxel accuracy. The phantom described in this paper was constructed to fit into a body coil of a MRI scanner, (external dimensions of the phantom were: 310 mm x 310 mm x 310 mm), and it contained 10,830 control points. With this phantom, the mean errors in the measured coordinates of the control points were on the order of 0.1 mm or less, which were less than one tenth of the voxel's dimensions of the phantom image. The calculated three-dimensional distortion map, i.e., the differences between the image positions and true positions of the control points, can then be used to compensate for geometric distortion for a full image restoration. It is anticipated that this novel method will have an impact on the applicability of MRI in both clinical and research settings. especially in areas where geometric accuracy is highly required, such as in MR neuro-imaging. (C) 2004 Elsevier Inc. All rights reserved.

A proposed scheme for comprehensive characterization of the measured geometric distortion in magnetic resonance imaging using a three-dimensional phantom

Recently, a 3-dimensional phantom that can provide a comprehensive, accurate and complete measurement of the geometric distortion in MRI has been developed. In this paper, a scheme for characterizing the measured geometric distortion using the 3-D phantom is described. In the proposed scheme, a number of quantitative measures are developed and used to characterize the geometric distortion. These measures encompass the overall and spatial aspects of the geometric distortion. Two specific types of volume of interest, rectangular parallelepipeds (including cubes) and spheres are considered in the proposed scheme. As an illustration, characterization of the geometric distortion in a Siemens 1.5T Sonata MRI system using the proposed scheme is presented. As shown, the proposed scheme provides a comprehensive assessment of the geometric distortion. The scheme can be potentially used as a standard procedure for the assessment of geometric distortion in MRI. (C) 2004 American Association of Physicists in Medicine.

Detection of lateral gene transfer among microbial genomes

An increasingly comprehensive assessment is being developed of the extent and potential significance of lateral gene transfer among microbial genomes. Genomic sequences can be identified as being of putatively lateral origin by their unexpected phyletic distribution, atypical sequence composition, differential presence or absence in closely related genomes, or incongruent phylogenetic trees. These complementary approaches sometimes yield inconsistent results. Not only more data but also quantitative models and simulations are needed urgently.

Self-awareness of Prospective Memory Failure in Adults with Traumatic Brain Injury

The frequency of prospective memory failure in individuals with severe traumatic brain injury (TBI) was investigated by comparison with a non-brain-injured control group. Self-awareness of prospective memory function was also assessed by comparing self-ratings with ratings by significant others. Study participants included 33 individuals with severe TBI and 29 non-brain-injured persons. Each participant nominated a close friend or relative who completed the informant's version of the questionnaire. Participants and their significant others both rated the participants' frequency of prospective memory lapses using the Comprehensive Assessment of Prospective Memory (CAPM). An independent groups design was adopted to compare the TBI and control groups. No significant difference was found between the TBI and control participants' self-ratings of frequency of prospective memory failure, but ratings by significant others were significantly different. The TBI group demonstrated less self-awareness (i.e. underestimated the frequency of prospective memory failure compared to significant others) than the control group.

Geometric distortion in clinical MRI systems - Part I: evaluation using a 3D phantom

Recently, a 3D phantom that can provide a comprehensive and accurate measurement of the geometric distortion in MRI has been developed. Using this phantom, a full assessment of the geometric distortion in a number of clinical MRI systems (GE and Siemens) has been carried out and detailed results are presented in this paper. As expected, the main source of geometric distortion in modern superconducting MRI systems arises from the gradient field nonlinearity. Significantly large distortions with maximum absolute geometric errors ranged between 10 and 25 mm within a volume of 240 x 240 x 240 mm(3) were observed when imaging with the new generation of gradient systems that employs shorter coils. By comparison, the geometric distortion was much less in the older-generation gradient systems. With the vendor's correction method, the geometric distortion measured was significantly reduced but only within the plane in which these 2D correction methods were applied. Distortion along the axis normal to the plane was, as expected, virtually unchanged. Two-dimensional correction methods are a convenient approach and in principle they are the only methods that can be applied to correct geometric distortion in a single slice or in multiple noncontiguous slices. However, these methods only provide an incomplete solution to the problem and their value can be significantly reduced if the distortion along the normal of the correction plane is not small. (C) 2004 Elsevier Inc. All rights reserved.

Burden of disease and injury in Aboriginal and non-Aboriginal populations in the Northern Territory

Objective: To quantify the burden of disease and injury for the Aboriginal and non-Aboriginal populations in the Northern Territory. Design and setting: Analysis of Northern Territory data for 1 January 1994 to 30 December 1998 from multiple sources. Main outcome measures: Disability-adjusted life-years (DALYs), by age, sex, cause and Aboriginality. Results: Cardiovascular disease was the leading contributor (14.9%) to the total burden of disease and injury in the NT, followed by mental disorders (14.5%) and malignant neoplasms (11.2%). There was also a substantial contribution from unintentional injury (10.4%) and intentional injury (4.9%). Overall, the NT Aboriginal population had a rate of burden of disease 2.5 times higher than the non-Aboriginal population; in the 35-54-year age group their DALY rate was 4.1 times higher. The leading causes of disease burden were cardiovascular disease for both Aboriginal men (19.1%) and women (15.7%) and mental disorders for both non-Aboriginal men (16.7%) and women (22.3%). Conclusions: A comprehensive assessment of fatal and non-fatal conditions is important in describing differentials in health status of the NT population. Our study provides comparative data to identify health priorities and facilitate a more equitable distribution of health funding.

Intracardiac echo guided valvuloplasty of a stenotic tricuspid prosthetic valve in a patient with idiopathic hypereosinophilic syndrome

A 52-year-old male with idiopathic hypereosinophilic syndrome (HES) was transferred to our institution following the development of acute respiratory failure and shock. He had previously undergone tricuspid valve replacement with bioprosthetic valves on two occasions: the initial surgery for severe native tricuspid valve stenosis and the redo surgery for severe prosthetic valve stenosis and regurgitation. Conventional imaging assessment using transoesophageal echocardiography was suboptimal and comprehensive assessment of prosthetic valve function was aided by the use of intracardiac echocardiography (ICE). ICE provided high quality 2D imaging of the prosthesis demonstrating thrombus-like material coating the inner surfaces of the prosthetic valve stents effectively forming a tunnel-like obstruction. Unusual hemodynamics secondary to severe tricuspid stenosis were demonstrated by CW Doppler with intermittent signal fusion resulting from blunted respiratory variation in the markedly elevated right atrial pressure relative to right ventricular pressure. Successful balloon valvuloplasty was performed with ICE proving highly valuable in guiding balloon position as well as monitoring the efficacy of the subsequent inflations.

Do process modelling techniques get better? A comparative ontological analysis of BPMN

Current initiatives in the field of Business Process Management (BPM) strive for the development of a BPM standard notation by pushing the Business Process Modeling Notation (BPMN). However, such a proposed standard notation needs to be carefully examined. Ontological analysis is an established theoretical approach to evaluating modelling techniques. This paper reports on the outcomes of an ontological analysis of BPMN and explores identified issues by reporting on interviews conducted with BPMN users in Australia. Complementing this analysis we consolidate our findings with previous ontological analyses of process modelling notations to deliver a comprehensive assessment of BPMN.

RSA-Grid: A grid computing based framework for power system reliability and security analysis

Grid computing is an emerging technology for providing the high performance computing capability and collaboration mechanism for solving the collaborated and complex problems while using the existing resources. In this paper, a grid computing based framework is proposed for the probabilistic based power system reliability and security analysis. The suggested name of this computing grid is Reliability and Security Grid (RSA-Grid). Then the architecture of this grid is presented. A prototype system has been built for further development of grid-based services for power systems reliability and security assessment based on probabilistic techniques, which require high performance computing and large amount of memory. Preliminary results based on prototype of this grid show that RSA-Grid can provide the comprehensive assessment results for real power systems efficiently and economically.

Audit and comprehensive health assessment programme in the primary healthcare of adults with intellectual disability: a pilot study

International research has demonstrated significant shortcomings in the health of adults with intellectual disability (ID). Because general practitioners (GPs) are the main providers of primary healthcare for this population, strategies to improve general practice care are an important aspect of rectifying these shortcomings. The present pilot study aimed to determine the effect of various interventions on health maintenance activities and to assess their acceptability to GPs, with a view to informing larger scale studies. The GPs were recruited through an earlier questionnaire-based postal survey. The GPs identified all their adult patients with ID, then obtained consent for participation from three patients randomly selected by the investigators. The GPs completed two self-evaluation forms and case note audits 12 months apart, read a synopsis of the relevant literature provided by the researchers, and completed a comprehensive health assessment (CHA) of their three patients. Forty-five GPs agreed to participate in the CHA programme (CHAP), and 15 completed the project. Thirty-eight patients completed the project. The number of patient-GP dyads who completed the project was too small to demonstrate statistically significant changes in health issues over time. The GPs found that the synopsis of the literature was the best intervention for increasing knowledge and was also the most practical to use in general practice. The CHAP was the intervention that prompted the most action from the GP which would not have been undertaken otherwise. The CHAP appeared to provide a superior review process compared to the other interventions used in the present study. The numbers of health maintenance activities found to be overdue and the number of health issues detected as a result of the process were considerable. The CHAP served as a communication tool and an educative instrument, providing a basis for future studies and strategies to improve the general practice care of adults with ID.

Concepts and tools for comprehensive sustainability assessments for tourism destinations: a comparative review

This paper reviews a wide range of tools for comprehensive sustainability assessments at whole tourism destinations, covering socio-cultural, economic and environmental issues. It considers their strengths, weaknesses and site specific applicability. It is intended to facilitate their selection (and combination where necessary). Tools covered include Sustainability Indicators, Environmental Impact Assessment, Life Cycle Assessment, Environmental Audits, Ecological Footprints, Multi-Criteria Analysis and Adaptive Environmental Assessment. Guidelines for evaluating their suitability for specific sites and situations are given as well as examples of their use.

Overview, critical assessment, and conservation implications of koala distribution and abundance

Regional and national surveys provide a broadscale description of the koala's present distribution in Australia. A detailed understanding of its distribution is precluded, however, by past and continuing land clearing across large parts of the koala's range. Koala population density increased in some regions during the late 1800s and then declined dramatically in the early 1900s. The decline was associated with habitat loss, hunting, disease, fire, and drought. Declines are continuing in Queensland and New South Wales. In contrast, dense koala populations in habitat isolates in Victoria and South Australia are managed to reduce population size and browse damage. Current understanding of koala distribution and abundance suggests that the species does not meet Australian criteria as endangered or vulnerable fauna. Its conservation status needs to be reviewed, however, in light of the extensive land clearing in New South Wales and Queensland since the last (1980s) broadscale surveys. Consequently, we recommend that broadacre clearing by curtailed in New South Wales and Queensland and that regular, comprehensive, standardized, national koala surveys be undertaken. Given the fragmentation of koala habitat and regional differences in the status of the koala, we recommended that studies on regional variation in the koala be intensified and that koala ecology in fragmented and naturally restricted habitats be developed. More generally, the National Koala Conservation Strategy should be implemented.