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Initial Feasibility (initial + feasibility)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Initial feasibility of a multi-station high resolution three-dimensional dark blood angiography protocol for the assessment of peripheral arterial disease

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2009
Georgeta Mihai PhD
Abstract Purpose To evaluate the feasibility of a multi-station three dimensional (3D) T1-weighted turbo spin echo (TSE) dark-blood Sampling Perfection with Application optimized Contrasts using different flip angle Evolution sequence (T1w-SPACE), to assess aorta, iliac, and superficial femoral (SFA) arteries (inflow vessels) by comparing it with a multi-station contrast enhanced MR angiography (CE-MRA) with identical resolution. Materials and Methods A total of 6 volunteers and 14 peripheral arterial disease (PAD) patients were included in the study. Abdominal and thigh T1w-SPACE and lower leg time-resolved MRA (TR-MRA) with low dose contrast were followed by 3-station CE-MRA. Quantitative measurements of lumen area at 17 locations from T1w-SPACE and CE-MRA were obtained. Additionally, vessel wall areas at the same locations were obtained from the T1w-SPACE images. Results Quantitative comparison of lumen areas with T1w-SPACE and CE-MRA revealed strong correlation between the two techniques and strong inter-observer agreement for each of the two imaging methods (r > 0.9; P < 0.001). Localized vessel wall area measurements obtained in PAD patients were significantly greater compared with those obtained in normal volunteers (mean difference 43.75 ± 12.46 mm2; P < 0.001). Stenosis severity obtained from T1w-SPACE localized measurements showed significant arterial area stenosis in PAD patients. Conclusion T1w-SPACE imaging of inflow vessels is feasible, and in addition to CE-MRA has the ability to assess atherosclerotic plaque and vascular remodeling. J. Magn. Reson. Imaging 2009;30:785,793. © 2009 Wiley-Liss, Inc. [source]

Design and testing of a virtual environment to train stroke patients with unilateral spatial neglect to cross a street safely

OCCUPATIONAL THERAPY INTERNATIONAL, Issue 1 2003
Health Studies, Professor Patrice L. (Tamar) Weiss Faculty of Social Welfare
Abstract Virtual reality (VR) entails the use of advanced technologies, including computers and various multimedia peripherals, to produce a simulated (that is, virtual) environment that users perceive as comparable to real world objects and events. In recent years, virtual reality technologies have begun to be used as an assessment and treatment tool in occupational therapy, in part because of the ability to create environments that provide patients with opportunities to engage in meaningful, purposeful tasks that are related to real-life interests and activities. The objective of this study was to determine the suitability and feasibility of using a PC-based, nonimmersive, VR system (that is, a system in which the user has a reduced sense of actual presence in and control over the simulated environment) for training individuals with unilateral spatial neglect to cross streets in a safe and vigilant manner. A virtual environment, consisting of a typical city street, was programmed using Superscape'sÔTM 3D-Webmaster, a 3D web-authoring tool. Twelve subjects, aged 55 to 75 years, participated in the initial feasibility study and, to date, a further eight subjects have participated in the intervention study. Six of the initial subjects and all eight of the intervention subjects had sustained a right hemispheric stroke at least 6 weeks prior to the study. The remaining subjects were healthy age-matched adults who were independently mobile and had no difficulty in crossing streets. The results show that this virtual environment was suitable in both its cognitive and motor demands for the targeted population and indicate that the virtual reality training is likely to prove beneficial to people who have difficulty with crossing streets. The generalizability of these results, and recommendations regarding the use of virtual reality as an occupational therapy intervention, must be substantiated by further studies using a range of VR platforms with people with different cognitive and motor disabilities. Copyright © 2003 Whurr Publishers Ltd. [source]

Constructive model predictive control for constrained nonlinear systems

OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 6 2008
De-Feng He
Abstract This paper develops a new model predictive control (MPC) design for stabilization of continuous-time nonlinear systems subject to state and input constraints. The key idea is to construct an analytic form of the controller with some undetermined parameters and to calculate the parameters by minimizing online a performance index. By using the method of control Lyapunov functions (CLFs), we construct an appropriate variation on Sontag's formula, with one degree of freedom reflecting ,decay rate' of CLFs. Moreover, the constructed univariate control law is used to characterize the terminal region that guarantees the feasibility of the optimal control problem. Provided that the initial feasibility of the optimization problem is satisfied, the stability of the control scheme can be guaranteed. An example is given to illustrate the application of the constructive MPC design. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Pediatric Health-Related Quality of Life: Feasibility, Reliability and Validity of the PedsQLÔ Transplant Module

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 7 2010
J. Weissberg-Benchell
The measurement properties of the newly developed Pediatric Quality of Life InventoryÔ (PedsQLÔ) 3.0 Transplant Module in pediatric solid organ transplant recipients were evaluated. Participants included pediatric recipients of liver, kidney, heart and small bowel transplantation who were cared for at seven medical centers across the United States and their parents. Three hundred and thirty-eight parents of children ages 2,18 and 274 children ages 5,18 completed both the PedsQLÔ 4.0 Generic Core Scales and the Transplant Module. Findings suggest that child self-report and parent proxy-report scales on the Transplant Module demonstrated excellent reliability (total scale score for child self-report ,= 0.93; total scale score for parent proxy-report ,= 0.94). Transplant-specific symptoms or problems were significantly correlated with lower generic HRQOL, supporting construct validity. Children with solid organ transplants and their parents reported statistically significant lower generic HRQOL than healthy children. Parent and child reports showed moderate to good agreement across the scales. In conclusion, the PedsQLÔ Transplant Module demonstrated excellent initial feasibility, reliability and construct validity in pediatric patients with solid organ transplants. [source]