Biomedical Engineering: Applications, Basis and Communications

In a previous study by the authors, steady flow fields in a model of abdominal aorta with its seven peripheral branches were reported. In the present study, the some aorta model was simulated numerically with a pulsatile inlet waves for both the resting and exercise conditions. The baseline pulsatile flow field was presented in terms of velocity vectors and iso-velocity contours as well as the wall shear stress (WSS) distribution and the recirculation zones. The time-averaged behavior of the flow field represented by the fluid dynamic factors was discussed. The results were consistent with those obtained experimentally and numerically by other investigators. It was also found that under the present conditions, the steady flow behavior could adequately describe the time-averaged behavior of its corresponding pulsatile case, particularly in the regions where convective flow dominated. The present computer code may provide a platform for clinical simulations.

For PET transmission imaging, the conventional iterative algorithms based on expectation maximization type algorithms, could not effectively converge to optimal image solution. In this study, we suggest a statistical model PET transmission data, and then investigate a class of gradient-based optimization algorithms for transmission image reconstruction including steepest ascent, conjugate gradient, and preconditioned conjugate gradient. From phantom studies, the preconditioned conjugate algorithms can converge to good image results within limited number of iteration. Combined with the suggested statistical model of transmission data, the preconditioned conjugate algorithms can also produce attenuation maps with accurate linear attenuation coefficients for clinical data.

The purposes of the present study were to (1) investigate the effects of the arm movement and initial knee joint angle employed in standing long jump by the ground reaction force analysis and three-dimensional motion analysis; and (2) investigate how the jump performance of the female gender related to the body configuration. Thirty-four healthy adult females performed standing long jump on a force platform with full effort. Body segment and joint angles were analyzed by three-dimensional motion analysis system. Using kinetic and kinematic data, the trajectories on mass center of body, knee joint angle, magnitude of peak takeoff force, and impulse generation in preparing phase were calculated. Average standing long jump performances with free arm motion were +1.5 times above performance with restricted arm motion in both knee initial angles. The performances with knee 90° initial flexion were +1.2 times above performance with knee 45° initial flexion in free and restricted arm motions. Judging by trajectories of the center mass of body (COM), free arm motion improves jump distance by anterior displacement of the COM in starting position. The takeoff velocity with 90° knee initial angle was as much as 11% higher than in with 45° knee initial angle. However, the takeoff angles on the COM trajectory showed no significant differences between each other. It was found that starting jump from 90° bend knee relatively extended the time that the force is applied by the leg muscles. To compare the body configurations and the jumping scores, there were no significant correlations between jump scores and anthropometry data. The greater muscle mass or longer leg did not correlated well with the superior jumping performance.

In this paper, a novel scheme has been proposed for image retrieval task using the feature extracted directly from a compressed or uncompressed image. The texture information is first extracted by exploiting the multiresolution nature of wavelet decomposition, which represent the horizontal, vertical and diagonal frequency distribution of an image. We then calculate the mean and standard deviation of wavelet coefficients of each sub-band as texture features. In additions, we also extract shape feature by using the fixed-resolution block representation, which divides the image into isometric blocks and calculate the overlapped degree of each block with binary codes. The experimental results show that the retrieval efficiency is considerably improved by the proposed approach.

A full-scale 3D anthropometric digital model system is a set of technology that combined with 3D digital imaging system, computer 3D image processing system, reverse engineering and Computer-Aided Design. The purpose of this studied is to make a full size solid breast model by using the 1:1 anthropometric digital model technique to assist breast reconstruction plastic surgery colon the same size of symmetrical breast of the patient. The full-sized simulating breast model created in this studied not only can assist plastic surgeons by making more symmetric breasts on the other side during the reconstruction of the breast surgeries, but also can go into a process of analyzing if the two sides of the breasts are symmetrical. This studied is used the 3D optics scanner to scan on patients' breasts to obtain the breast 3D image data and then used reverse engineering technique and CAD software to simulate and to analyze the 3D image model of the reconstruction breasts. If this type of solid model is needed during the medical treatment, it can apply 3D digital data into a Rapid Prototyping machine to make the full-sized solid model. Doctors can using this solid model go into a process of evaluation and planning before the surgeries and consider being an important reference on breast reconstruction surgeries so that it can reduce patients' inconvenience and promote the medical treatment qualities.

Interface stresses are an important consideration in stump and socket for a prosthetic limb to a person with transtibial amputation. During stance phase of the gait cycle, the prosthetic socket is expected to support and distribute the entire body weight of the patient. Excessive stresses between stump and socket will induce pain, discomfort and breakdown of soft tissues. The objectives of this study are to investigate the differences of gait, the maximum forces and pressures between stump and socket during different walking speed. Motion analysis system was applied to investigate the kinematics and kinetics of the gait and the Pedar system was used to measure the maximum forces and pressures between stump and socket during different walking speeds. Fifteen male subjects with transtibial amputation were collected in this research. These subjects were required to walk in three different speeds (85 steps/min, 95 steps/min, 115 steps/min). The maximum force, pressure and forcetime integrals in head of fibula, patellar ligament, medial condyle of tibia, tibial end and fibular end were recorded. The results showed that, the range of motion and the moment in hip, knee and ankle joint increased as the walking speed. Maximum forces and pressures in the measured areas had no significant difference in multiple axis prosthetic foot when the walking speed increased. The distributions of the force-time integrals were the same when compared with maximum force and the pain scale of subjects' subjective feeling. Walking speed would not influence the maximum force and pressure when subjects were in single axis prosthetic foot. This study provided the objective and subjective data for prosthetist or physician when applied on amputees.