Biomedical subjects

N Shareef

Publications and source records attributed to N Shareef.

5 recordsLinked to original sources

PubMed1999

Segmentation of medical images using LEGION.

Advances in visualization technology and specialized graphic workstations allow clinicians to virtually interact with anatomical structures contained within sampled medical-image datasets. A hindrance to the effective use of this technology is the difficult problem of image segmentation. In this paper, we utilize a recently proposed oscillator network called the locally excitatory globally inhibitory oscillator network (LEGION) whose ability to achieve fast synchrony with local excitation and desynchrony with global inhibition makes it an effective computational framework for grouping similar features and segregating dissimilar ones in an image. We extract an algorithm from LEGION dynamics and propose an adaptive scheme for grouping. We show results of the algorithm to two-dimensional (2-D) and three-dimensional (3-D) (volume) computerized topography (CT) and magnetic resonance imaging (MRI) medical-image datasets. In addition, we compare our algorithm with other algorithms for medical-image segmentation, as well as with manual segmentation. LEGION's computational and architectural properties make it a promising approach for real-time medical-image segmentation.

Algorithms↗

PubMed1999

Interactive volume visualizations for synchronous and asynchronous remote collaboration.

The value of information acquisition is not simply to acquire data at increased precision, but to make these data both available and usable to as many specialists as possible. We have developed a working prototype for intuitive realtime interaction over the Internet. Current scenarios include use by expert head and neck surgeons, for use in preoperative assessment of head and neck cancers, and remote synchronous collaboration scenarios such as expert-expert and expert-referring physician. This prototype demonstrates a shared virtual environment that allows multiple users to interactively manipulate large volumetric data sets across long distances. The system is easily extensible to many other applications that utilize discrete data sampling and thus is readily extensible to a wide range of scientific investigations.

Head and Neck Neoplasms↗

PubMed1998

A comparative analysis of integrating visual representations with haptic displays.

As further advances in visual display technologies and force feedback devices are integrated in virtual systems, questions remain: What level of reality does the system provide to the user? Is the environment convincing enough to engage the user and to maximize transfer? Are the visual and haptic displays fully integrated to provide seamless operation in the simulated environment? Does the system provide not only the ability to navigate through a simulated environment, but also realistic interaction with instrumentation and structures? We report on our advances in developing a virtual simulation system for training in functional endoscopic sinus surgery (FESS). Specifically, we will present work on subject trials exploring the realism provided by integrated visual and haptic displays, and compare and contrast surface vs. volume representation for presenting realistic models of the anatomy for surgical interaction.

Computer Simulation↗

PubMed1996

Effect of manufacturing tolerances on the micromotion at the Morse taper interface in modular hip implants using the finite element technique.

This study reports on the examination of the effect of manufacturing tolerances on the micromotion at the Morse taper interface in modular hip implants. The finite element technique was used as a tool of analysis. Special emphasis was placed on the consideration of the transient dynamic conditions under which a prosthesis works inside the human body. In order to simulate approximately the repetitive forces acting on a hip implant during the human walking cycle, a time-variant sinusoidal load was applied on the head of the taper. The locking of the Morse taper joint by the surgeon in the operating room at the time of implantation was simulated by specifying an axial displacement to the female taper component as an initial condition.

Biomechanical Phenomena↗

PubMed1996

Cranial base tumor visualization through high-performance computing.

Tumors of the skull base in general are considered among the more difficult head and neck pathological entities to treat surgically; some surgeons, in fact, consider lesions in this area inoperable. The most appropriate and safest surgical approach to lesions of the anterior and lateral skull base can be devised only with accurate and precise pre-operative assessment. The literature demonstrates the constant evolution of and search for more efficient less invasive, and safe surgical approaches to this region. With the development of a more exact three-dimensional, interactive anatomical "road map" for each patient's disease and anatomy, the skull base surgeon can not only achieve a more accurate pre-operative assessment leading to a less invasive and less morbid approach, but also can continue to develop and refine new approaches without fear of actual morbidity and mortality. An interdisciplinary team approach, the advent and continued development of faster high performance computers, and the development of new and innovative rendering algorithms can lead to surgical simulation. A prototype of an interactive system has been developed. The system will be iteratively modified through a stepwise evaluation of its clinical usefulness by continually reassessing the system with clinical trials. The current state of the system and the potential benefits are presented.

Brain Mapping↗