Yiyu Cai

Real-Time Interactive Simulator for Percutaneous Coronary Revascularization Procedures

This article describes the simulation of real-time catheter navigation in our interactive interventional cardiology simulation system (ICard). ICard is designed to enable medical students or physicians to familiarize themselves with the techniques of interventional catheterization procedures. The ICard software provides three-dimensional (3-D) views of the blood vessels and fluoroscopic images for real-time visualization of the catheter position. The 3-D human vasculature is built from various image data sets and is represented with a central line hierarchy model. Navigation of the catheter and guide wire and their interaction with blood vessels are implemented by applying the finite element method. Physical modeling that features the elasticity of the catheter and guide wire was developed to provide a realistic simulation of catheterization procedures. An electromechanical device was also developed in the system, allowing physical manipulation of catheter and guide wire movements. ICard can be used for training and design of equipment for interventional cardiology and may be further extended for pretreatment planning.

Interpolation over arbitrary topology meshes using a two-phase subdivision scheme

The construction of a smooth surface interpolating a mesh of arbitrary topological type is an important problem in many graphics applications. This paper presents a two-phase process, based on a topological modification of the control mesh and a subsequent Catmull-Clark subdivision, to construct a smooth surface that interpolates some or all of the vertices of a mesh with arbitrary topology. It is also possible to constrain the surface to have specified tangent planes at an arbitrary subset of the vertices to be interpolated. The method has the following features: 1) it is guaranteed to always work and the computation is numerically stable, 2) there is no need to solve a system of linear equations and the whole computation complexity is O(K) where K is the number of the vertices, and 3) each vertex can be associated with a scalar shape handle for local shape control. These features make interpolation using Catmull-Clark surfaces simple and, thus, make the new method itself suitable for interactive free-form shape design.

Training and pretreatment planning of interventional neuroradiology procedures--initial clinical validation.

A PC based system for simulating image-guided interventional neuroradiological procedures for physician training and patient specific pretreatment planning is described. The system allows physicians to manipulate and interface interventional devices such as catheters, guidewires, stents and coils within 2-D and hybrid surface and volume rendered 3-D patient vascular images in real time. A finite element method is employed to model the interaction of the catheters and guidewires with the vascular system. Fluoroscopic, roadmapping and volume rendered 3-D presentations of the vasculature are provided. System software libraries allow for the use of commonly employed catheters, guidewires, stents and occluding coils of various shapes and sizes. The results of an initial clinical validation suggest that the experience gained from our simulator is comparable with that of using a vascular phantom. We are conducting further validation with the aim of providing patient specific pretreatment planning.

VR simulated training for less invasive vascular intervention

Abstract This paper describes a computerized simulation system for less invasive vascular interventions using virtual-reality (VR)-based technology. A virtual human patient is constructed on top of the visible human data (VHD) incorporating in various vascular disease cases. Specially, the human vascular network is modeled for the use of catheterization simulation. Physical modeling technique is applied to model the interaction between the blood vessels and vascular catheterization devices. A haptic interface is integrated with the computer simulation system to provide tactile sensations to the user during the simulated catheterization procedures. The system can be used for training and pre-treatment planning of interventional vascular procedures.

Bio-edutainment: Learning life science through X gaming

Learning through gaming is one of the natural ways for knowledge and skill acquisition. This paper presents our work on bio-edutainment. Playing X games not only allows low age students to learn bio-molecular structure but also enables better understand complicated structure of bio-molecules. Immersive and interactive games may potentially motivate students to develop their interest to explore the wonder of life science. Based on our core Virtual Reality technology, the bio-edutainment system developed consists of mainly three components of visualization, modeling and interaction. Enabling technology includes also GPU technology, Networking, sensor technology and so on. The system was exhibited in Singapore Science Center.

Computer environment for interventional neuroradiology procedures

This article addresses the design and development of a computer-based medical simulation system (NeuroCath) for training and patient-specific planning of interventional neuroradiology procedures. NeuroCath includes three main components: vascular extraction and modeling, instrument navigational simulations, and realistic human-computer interfaces. As the basis of the simulation, the vascular model is constructed from images obtained from different modalities such as X-ray, magnetic resonance imaging, and computerized tomography data. The model takes into account topological, geometrical, and physical properties of the patient’s vasculature. A finite element method–based physical model is constructed to simulate the behavior of interventional radiological instruments and devices within vessels during the interventional radiology processes. Realistic human-computer interfaces are provided in accordance with the actual interventional radiology environment. These interfaces include the video monitors displaying the simulated X-ray images and the haptic apparatus providing physicians with realistic tactile feedback encountered in the catheterization procedures.

Immersive protein gaming for bio edutainment

Games have long been used as a tool for teaching important subject matter, from concept building to problem solving. Through fun learning, students may further develop their curiosities and interest in their study. This article addresses the issue of learning biomolecular structures by virtual reality gaming. A bio edutainment solution featuring stereographic visualization, 3D modeling, and game interaction is developed for students to learn amino acids, α-helices, β-sheets, and other protein structure information. A pilot study is performed in this work with Singapore Chinese High School; initial results of this study are presented.

Making Doo-Sabin surface interpolation always work over irregular meshes

This paper presents a reliable method for constructing a control mesh whose Doo-Sabin subdivision surface interpolates the vertices of a given mesh with arbitrary topology. The method improves on existing techniques in two respects: (1) it is guaranteed to always work for meshes of arbitrary topological type; (2) there is no need to solve a system of linear equations to obtain the control points. Extensions to include normal vector interpolation and/or shape adjustment are also discussed.

Geometric Feature Detection for Reverse Engineering Using Range Imaging

Abstract The use of range imaging has been gaining popularity in reverse engineering. One challenging task is the detection of feature information from range images. In this paper, an approach to detect geometric features from range images using a fuzzy partitioning theory and geometric invariants is developed. Based on the fuzzy C-shell clustering technique, quadric features are partitioned into primitive clusters. Instead of performing sequential model fittings, general quadric surfaces as object shells are fitted concurrently. The geometric representations of prototypes are generated during the above process of pattern classifications. The integration of the partition with the invariant analysis makes it possible to detect geometric features from depth maps for the development of reverse engineering.

Parametric Eyeball Model for Interactive Simulation of Ophthalmologic Surgery

In this paper, we describe a parametric eyeball modeling system for real-time simulation of eye surgery. A knowledge-based approach is used to parametrically model the ophthalmologic structures. Together with the parametric eye modeling and the integration of patient-specific disease images, the ophthalmologic knowledge databases of eye diseases, eye material properties, and eye surgical instruments and procedures can help to provide better maneuverability and more realistic scenanos for eye surgical simulation. A customized Finite Element Method (FEM) is developed to analyze the deformation of the eyeball and the interactions between the bio-structures and the instruments in the surgery simulation. A phantom haptic and force feedback virtual environment is used for real-time interactive ophthalmologic surgical simulation.