PubMed Health⌕ Search

Biomedical subjects

Pheng-Ann Heng

Publications and source records attributed to Pheng-Ann Heng.

17 recordsLinked to original sources
PubMed2006

Segmentation and three-dimension reconstruction of Chinese digitized human cerebrum.

OBJECTIVE: A 3D digitized visible model of human cerebrum was built to provide anatomical structure for making plans of cerebral surgical operation and realizing accurate simulation of cerebrum on computer. METHODS: Transverse sectional anatomy data of the cerebrum were chosen from the first Chinese visible human (one male and one female). Semi-automated segmentation and Photoshop software were selected to segment cerebral cortex, white matter, basal nuclei, lateral ventricle, hippocampus, etc. On personal computer, the segmented structures were reconstructed in 3D with volume rendering reconstruction and surface rendering reconstruction. RESULTS: Two accurately segmented images of the main structures of cerebrum were completed. The reconstructed structures can be displayed singly, in small groups or as a whole and can be continuously rotated in 3D space at different velocities. CONCLUSION: Combining volume-rendering reconstruction with surface rendering reconstruction overcomes the defects of surface rendering reconstruction that lack of internal anatomical information, which provides a new method for 3D reconstruction. The reconstructed cerebrum and the main internal structures are realistic, which demonstrates the natural shape and exact position of the structures. It provides an accurate model for the automated segmentation algorithmic study and provides a digitized anatomical mode of cerebrum.

China↗
PubMed2006

Chinese visible human project.

Research on the digital visible human is of great significance and has considerable application value. The US visible human project created the first digital image dataset of a complete human (one male and one female) in 1995. To promote worldwide application-oriented visible human research, additional visible human datasets, representative of different populations of the world, are needed. The Chinese visible human (CVH) male (created in October 2002) and female (created in February 2003) Project achieved greater integrity of images, better blood vessel identification, and were free of organic disease. The most noteworthy technical advance of the Chinese visible human project (CVHP) was the construction of a low temperature laboratory, which prevented loss of small structures (including teeth, nasal conchae, and articular cartilage) from the milling surface. Thus, better integrity of images was achieved. To date, we have acquired five CVH datasets and volume rendered them for visualization on a PC. 3D reconstruction of some organs and structures has been completed and work to segment a complete dataset is under way. Although there is still a long way to go to make the visible human meet the application-oriented needs in various fields, progress is being made toward acquiring new datasets, performing segmentation, and setting up a platform of computer-assisted medicine. Here, we review the history and highlights of the CVHP and foresee its future development as well.

Anatomy↗
PubMed2006

Virtual reality techniques. Application to anatomic visualization and orthopaedics training.

Surgical training systems using virtual reality simulation techniques offer a cost-effective alternative to traditional training methods. In this sense, techniques for interactive visualization and virtual reality surgery have been one of the very important research areas. We describe various techniques we have used in developing a virtual reality system for anatomic visualization and training arthroscopic knee surgeons. Virtual models used in our systems are constructed from the Visible Human Project and Chinese Visible Human data sets. We present our various developments in segmentation, personal-computer-based real-time volume visualization, soft tissue deformation with topological change in real-time using finite element analysis, and soft tissue cutting with tactile feedback.

Arthroscopy↗
PubMed2006

Boundary enhancement and speckle reduction for ultrasound images via salient structure extraction.

In this paper, we present an approach for medical ultrasound (US) image enhancement. It is based on a novel perceptual saliency measure which favors smooth, long curves with constant curvature. The perceptual salient boundaries of tissues in US images are enhanced by computing the saliency of directional vectors in the image space, via a local searching algorithm. Our measure is generally determined by curvature changes, intensity gradient and the interaction of neighboring vectors. To restrain speckle noise during the enhancement process, an adaptive speckle suspension term is also combined into the proposed saliency measure. The results obtained on both simulated images and medical US data reveal superior performance of the novel approach over a number of commonly used speckle filters. Applications of US image segmentation show that although the proposed algorithm cannot remove the speckle noise completely and may discard weak anatomical structures in some case, it still provides a considerable gain to US image processing for computer-aided diagnosis.

Algorithms↗
PubMed2006

Intelligent inferencing and haptic simulation for Chinese acupuncture learning and training.

This paper presents an intelligent virtual environment for Chinese acupuncture learning and training using state-of-the-art virtual reality technology. It is the first step toward developing a comprehensive virtual human model for studying Chinese medicine. Students can learn and practice acupuncture in the proposed 3-D interactive virtual environment that supports a force feedback interface for needle insertion. Thus, students not only "see" but also "touch" the virtual patient. With high performance computers, highly informative and flexible visualization of acupuncture points of various related meridian and collateral can be highlighted to guide the students during training. A computer-based expert system using our newly proposed intelligent fuzzy petri net is designed and implemented to train the students to treat different diseases using acupuncture. Such an intelligent virtual reality system can provide an interesting and effective learning environment for Chinese acupuncture.

Acupuncture↗
PubMed2006

Virtual acupuncture human based on chinese visible human dataset.

In this paper, we present our application of latest information technology in assisting the Chinese acupuncture research. Having integrated the Chinese Visible Human (CVH) data, virtual reality, visualization and imaging techniques, we have constructed a 3-dimensional digital human model for acupuncture. This model integrates the meridian positioning, acupoint positioning, arbitrary cutting-plane visualization, multi-layer dissection, needle puncturing simulation, as well as the common diseases-therapy information. Our work can be widely applied to Chinese acupuncture education, clinical usage and scientific research.

Acupuncture↗
PubMed2005

Support vector clustering for brain activation detection.

In this paper, we propose a new approach to detect activated time series in functional MRI using support vector clustering (SVC). We extract Fourier coefficients as the features of fMRI time series and cluster these features by SVC. In SVC, these features are mapped from their original feature space to a very high dimensional kernel space. By finding a compact sphere that encloses the mapped features in the kernel space, one achieves a set of cluster boundaries in the feature space. The SVC is an effective and robust fMRI activation detection method because of its advantages in (1) better discovery of real data structure since there is no cluster shape restriction, (2) high quality detection results without explicitly specifying the number of clusters, (3) the stronger robustness due to the mechanism in outlier elimination. Experimental results on simulated and real fMRI data demonstrate the effectiveness of SVC.

Algorithms↗
PubMed2005

Shape modeling using automatic landmarking.

This paper describes a novel approach to automatically recover accurate correspondence over various shapes. In order to detect the features points with the capability in capturing the characteristics of an individual shape, we propose to calculate the skeletal representation for the shape curve through the medial axis transform. Employing this shape descriptor, mathematical landmarks are automatically identified based on the local feature size function, which embodies the geometric and topological information of the boundary. Before matching the resulting landmarks, shape correspondence is first approached by matching he major components of the shape curves using skeleton features. This helps in keeping the consecutive order and reducing the search space during the matching process. Point matching is then performed within each pair of corresponding components by solving a consecutive assignment problem. The effectiveness of this approach is demonstrated through experimental results on several different training sets of biomedical object shapes.

Algorithms↗
PubMed2004

An efficient and scalable deformable model for virtual reality-based medical applications.

Modeling of tissue deformation is of great importance to virtual reality (VR)-based medical simulations. Considerable effort has been dedicated to the development of interactively deformable virtual tissues. In this paper, an efficient and scalable deformable model is presented for virtual-reality-based medical applications. It considers deformation as a localized force transmittal process which is governed by algorithms based on breadth-first search (BFS). The computational speed is scalable to facilitate real-time interaction by adjusting the penetration depth. Simulated annealing (SA) algorithms are developed to optimize the model parameters by using the reference data generated with the linear static finite element method (FEM). The mechanical behavior and timing performance of the model have been evaluated. The model has been applied to simulate the typical behavior of living tissues and anisotropic materials. Integration with a haptic device has also been achieved on a generic personal computer (PC) platform. The proposed technique provides a feasible solution for VR-based medical simulations and has the potential for multi-user collaborative work in virtual environment.

Algorithms↗
PubMed2004

A virtual-reality training system for knee arthroscopic surgery.

Surgical training systems based on virtual-reality (VR) simulation techniques offer a cost-effective and efficient alternative to traditional training methods. This paper describes a VR system for training arthroscopic knee surgery. Virtual models used in this system are constructed from the Visual Human Project dataset. Our system simulates soft tissue deformation with topological change in real-time using finite-element analysis. To offer realistic tactile feedback, we build a tailor-made force feedback hardware.

Arthroplasty↗
PubMed2004

The Chinese Visible Human (CVH) datasets incorporate technical and imaging advances on earlier digital humans.

We report the availability of a digitized Chinese male and a digitzed Chinese female typical of the population and with no obvious abnormalities. The embalming and milling procedures incorporate three technical improvements over earlier digitized cadavers. Vascular perfusion with coloured gelatin was performed to facilitate blood vessel identification. Embalmed cadavers were embedded in gelatin and cryosectioned whole so as to avoid section loss resulting from cutting the body into smaller pieces. Milling performed at -25 degrees C prevented small structures (e.g. teeth, concha nasalis and articular cartilage) from falling off from the milling surface. The male image set (.tiff images each of 36 Mb) has a section resolution of 3072 x 2048 pixels ( approximately 170 micro m, the accompanying magnetic resonance imaging and computer tomography data have a resolution of 512 x 512, i.e. approximately 440 micro m). The Chinese Visible Human male and female datasets are available at http://www.chinesevisiblehuman.com. (The male is 90.65 Gb and female 131.04 Gb). MPEG videos of direct records of real-time volume rendering are at: http://www.cse.cuhk.edu.hk/~crc

Adult↗
PubMed2004

Interactive cutting simulation with adaptive refinements using digital logic design analogy.

A major requirement for surgical simulation is to allow virtual tissue cutting. This paper presents a scalable and adaptive cutting technique based on a mass-spring mesh. By the analogy of digital logic design, an arbitrary incision is modeled systematically by translating the cutting process into a state diagram. Subdivision of mesh elements is driven by the state transitions. Node redistribution, local re-meshing and deformation are applied to refine the subdivided mesh.

Computer Simulation↗
PubMed2004

Virtual reality based system for training on knee arthroscopic surgery.

Surgical training systems based on virtual reality (VR) and simulation techniques offer a cost-effective and efficient alternative to traditional training methods. This paper describes a virtual reality system for training arthroscopic knee surgery. The virtual model used in this system is constructed from the Visual Human Project dataset. The system simulates the real-time deformation of soft tissue with topological change using finite element analysis. To offer the realistic tactile feedback, we construct a specialized force feedback hardware.

Arthroscopy↗
PubMed2003

Creation of the Chinese visible human data set.

The United States Visible Human Project (VHP) created a digital image data set of complete human male (data acquisition finished in November 1994) and female (data acquisition finished in December 1995) cadavers in magnetic resonance imaging (MRI), computed tomography (CT), and anatomical (anatomic serial section) modes. VHP aroused worldwide enthusiasm for Visible Human Research (VHR), and the data set is being used in a variety of research and educational domains. The Visible Korean Human (VKH) male was produced in March 2001. To accelerate worldwide VHR and to promote virtual anatomy as a revolutionary break with conventional anatomy, more visible human data sets representative of different populations of the world are in demand. The Chinese Visible Human (CVH) male (created in October 2002) and female (created in February 2003) project achieved greater integrity of images, easier blood vessel identification, and were free of organic lesion (unlike the other visible human projects). We performed data acquisition, three-dimensional (3D) reconstruction, and visualization with improved technology to create CVH male and female. CVH is the first volumetric data representing a complete normal adult human male and female of an Asian population. This article presents the history of Chinese Visible Human cadavers and the methods and technology used to produce the data set.

Anatomy, Cross-Sectional↗
PubMed2003

Interactive deformation of soft tissues with haptic feedback for medical learning.

An effective deformable model based on a successive force propagation process is proposed. It avoids the laborious stiffness matrix formulation and is scalable simply by controlling the penetration depth. Mechanical tests are performed to evaluate its feasibility for modeling real tissues. An interactive system is developed using a commercial haptic device.

Computer Simulation↗
PubMed2003

A haptic needle manipulation simulator for Chinese acupuncture.

Chinese acupuncture is a traditional medical treatment in Chinese history. Recent evidence shows that this treatment is effective. However, acupuncture students can only practice on either real patients or mannequin. In this project, we propose a virtual reality training system for acupuncture. The system not just provides 3D stereo display, but also realistic haptic feedback in real-time. Since acupuncture usually involves thrust-and-lift needle motion, we also propose a bi-directional haptic model to tailor this application. Our results show that the novel haptic model confirms with practitioners' tactile experience.

Acupuncture↗