Biomedical Engineering: Applications, Basis and Communications

Warfarin is a frequently used oral anticoagulant for long-term prevention and treatment of thromboembolic events. Due to its narrow therapeutic range and large inter-individual dose–response variability, it is highly desirable to personalize warfarin dosing. However, the complexity of the conventional kinetic-pharmacodynamic (K-PD) models hampers the development of the personalized dose management. To avert this challenge, we propose simplified PD models for warfarin dose-INR response relationship, which is motivated by ideas from control theory. The simplified models were further applied to longitudinal data of 37 patients undergoing anticoagulation treatment using the standard two-stage approach and then compared with the conventional K-PD models. Data analysis shows that all models have a similar predictive ability, but the simplified models are most parsimonious.

The aim of this study was to find the time window for monitoring early radiation-induced liver injury (RILI) of rats using ferucarbotran-enhanced magnetic resonance imaging (MRI) at 3 T. Six rats were irradiated with 20 Gy 6 MV X-ray on right side liver and the other six non-irradiated rats were used as the control. Three or four days after irradiation, the rats were examined using MRI. The conventional spin echo (CSE) pulse sequence with various scanning parameters (CSE1: TR/TE = 200/8 ms, CSE2: TR/TE = 1000/8 ms and CSE3: TR/TE = 1000/22 ms) was performed before, 20 min, 1 h, 7 days, 14 days and 21 days after injecting 80 μmol/kg ferucarbotran, a kind of commercialized superparamagnetic iron oxide (SPIO). The ferucarbotran particles were macrophaged by Kupffer cells and this caused decreased signal intensity on MR images because of the T₂ and susceptibility effect. The irradiated liver had less reduction of MR signal intensity than the non-irradiated liver because radiation impaired the function of Kupffer cells. All CSE images of the irradiated group showed higher right-to-left ratio of the MR signal intensity in the liver than the control group after ferucarbotran injection. Furthermore, CSE2 demonstrated higher efficacy than CSE1 and CSE3. The optimal time window to observe an obvious contrast between the right side and left side liver in the irradiated group was from 20 min to 7 days after a single bolus injection of ferucarbotran. This protocol may be helpful to investigate the effects of radioprotectors and radiosensitizers on the reticuloendothelial system.

Background: Gastrointestinal tract pressure information can reflect the dynamic disorder of gastrointestinal tract physiological and pathological changes, which is important in early diagnosis and treatment of gastrointestinal diseases. However, the rule of human gastrointestinal activities under his normal state is still not clear. The purpose of this paper is to find some rules of gastrointestinal activities using wavelet transform-fractal algorithm and provides a reference for the diagnosis of gastrointestinal disease. Methods: Data from 16 healthy subjects (13 men and three women) aged 18–35 years were analyzed. The key challenges on the data processing were filtering, features extraction, information evaluation and providing the reference conclusion which were resolved by employing wavelet decomposition, fractal algorithm etc. Key Results: About 94% of the subjects gastrointestinal activities follow the rule that the colonic activities in the digestive period are the roughest with the largest box dimension, closely followed by small intestinal activities with gastric activities ranking third with the smallest box dimension, which is never revealed before. Moreover, for the same person the gastrointestinal activities in the digestive period are rougher than in the inter-digestive period, as the box dimension of gastrointestinal activities in the digestive period is larger than in the inter-digestive period. Conclusions and Inferences: The results show that the wavelet transform-fractal algorithm provides a new way to research human gastrointestinal activities.

We present the use of Extended Modified Lambert–Beer model for optical monitoring of mean blood oxygen saturation (S_mO₂) via a fitting procedure. This work focuses on the absorption characteristics of hemoglobin derivatives in the wavelength range of 520–600 nm to give the best estimates of S_mO₂. The study of the feasibility of applying this analytic method to skin oximetry is via spectroscopy data collected from fingertips of four healthy volunteers both at rest and during arterial blood occlusion condition. The results revealed a decrease in the mean of mean and standard deviation of S_mO₂ value of fingertips from 94.5 ± 2.19% when volunteers were at rest to 56.76 ± 5.8% during the arterial blood occlusion measurement. The larger variation in the value estimated for blood occlusion condition could be a result of differences in volunteers' physical fitness and hypertension status. These estimated S_mO₂ values agreed reasonably well with the value reported in most of the previous studies. This work concluded that the proposed technique can potentially be used as a complementary technique to clinical assessment of skin grafts and burnt skin.

A volume based surgery simulator described herein provides cutting simulations for diverse tools used in spine surgery and morphological simulations of bone reposition, deletion and fusion. A tool coordinate based method is used to obtain constant and simple surface equations for representing the tools. Such representations give efficient computations for cutting surface changes and calculate pre-computed transformations for fast summating the cutting force vectors along the haptic device axes from chip removal loads on a tool surface. This study extends the traditional one-scalar volume with geometric and topologic data. Real-time cutting simulations for predicting tissue surface changes and cutting forces can be achieved by manipulating extended geometric volume data. The manipulation of extended topological volume data can detect new separate bones generated during the cutting simulations and enables morphological simulations of repositioning, deleting or fusing the separate bones. Realistic 3D images with fine tissue surface features obtained from simulating three typical surgeries located on the cervical, thoracic and lumbar spine respectively demonstrate that the proposed simulator can be an excellent tool for planning, confirming and rehearsing various complex spine surgeries such as abnormal tissue removal, spine decompression and morphology correction.

Sensitivity performance is one of the key issues in multi-pinhole collimator design for small animal pinhole Single photon emission computed tomography (SPECT). Currently, there are two approaches in predicting sensitivity performance: analytical formula and Monte Carlo (MC) simulation. Analytical formula offers fast computation, while MC simulation provides better modeling of various physical effects and generates more accurate sensitivity prediction. Tilted pinhole apertures become popular in modern system design, because they can avoid projection overlapping and increase field-of-view (FOV) compared to traditional multiple pinholes. However, conventional analytical formula for sensitivity prediction cannot be directly applied to tilted apertures. In this research, we present a modified analytical formula to predict the sensitivity performance by considering tilted and translated pinhole apertures in a multi-pinhole collimation design. The modification is based on a construction of a virtual object plane which is parallel to the aperture plane in the tilted pinhole. Since the new formula is derived in the vector domain, it can be readily integrated to computer-aided-design software to greatly simplify the collimator design optimization. The results show that the modified formula generates sensitivity prediction similar to that from the MC simulation for a multi-pinhole system with tilted pinholes. When larger tilted pinholes are used to increase FOV, the formula can also accurately generate sensitivity prediction with a slightly reduced peak value. For a tilted pinhole aperture up to 40°, the simulation results indicate that the conventional analytical formula may overestimate as much as 25% sensitivity.

A pulse oximeter is a noninvasive instrument used in clinical medicine to monitor arterial oxygen saturation. Fingertip-type pulse oximeters are popular, but their inconvenience for long-term monitoring in daily life means that other types of wearable pulse oximeters, such as a ring-type reflection pulse oximeter, needs to be developed. However, designing a ring-type pulse oximeter for measuring the oxygen saturation is difficult due to the complex tissue architecture of the finger base. This study used human tissue simulations to evaluate the practicability of a ring-type reflection pulse oximeter design. Moreover, given that the collection of diffusely reflected light can be enhanced by using a parabolic reflector, the efficacy of a ring-type reflection pulse oximeter with a parabolic reflector was also evaluated.

To develop a more convenient electromyography (EMG) signal acquisition system for masticatory muscles (MMs) will have implication for the diagnosis of disease of stomatological system and functional reconstruction in dentistry. This study attempted to design a multi-channel MM surface electromyography (s-EMG) signal acquisition system which has high common mode rejection ratio (CMRR) and preamplifier system. In this system, a USB graphical interface technology on windows operating system was specifically designed and s-EMG data were analyzed by a combination of time domain, frequency domain, time-frequency, several spectral analysis, wavelets and other special algorithms under multi-parameter. Then the EMG data from some patients with stomatological dysfunction in temporomandibular joint (TMJ) clinic and a control group from dental school students were acquired and analyzed. The data indicate that the s-EMG signal acquisition system which has been built is simple and useful in aiding diagnosis and treatment evaluation of temporomandibular disorders.

In this paper, a prototype of wearable and wireless electrocardiography (ECG) monitoring system is developed and implemented on DSP and PDA. We present a real-time extended Kalman filtering framework for extracting motion and electromyography (EMG) artifacts from a single-channel ECG in wearable systems as different from other offline studies. Realized prototype is a good example for the usage of the Kalman filter in biomedical real-time system. The average SNR advancement of 9.1430 dB was achieved for denoising, which is average 1 dB more than the other methods such as MABWT, EKF2 by using MIT-BIH database. Additionally, the usability and performances of conductive textile electrodes were evaluated with disposable Ag–AgCl electrodes by using daily activities. A novel textile electrode gave approximately 25.23% better results compared to Ag–AgCl electrodes. Also, UDP, TCP and Web Socket communication protocols have been tested. UDP has been the fastest method for the ECG signal transferring from the patient to the doctor. At the same time, a method is proposed for direct access to the patient by the doctor. The results illustrate that this type of system will submit highly ergonomic solutions among biomedical device technologies. In addition, the usage of such kinds of systems is foreseen for requiring long-term follow-up and disorders.

A novel method based on the finite element modeling and simulation of human musculoskeletal system was proposed to evaluate the human locomotion ability in this paper. Biomechanical models that compute muscle forces and human joint forces are broadly applicable to the study of factors that promote human musculoskeletal injury and optimize musculoskeletal motion planning. However, it is still difficult to acquire the biomechanical characteristics of human skeletal system in vivo. Especially, there is little research about the biomechanical modeling and simulation of the entire human skeletal system. The finite element method was broadly used various mechanical analyses. It has been used to model and simulate biomechanical behavior of segments of human skeletal system, such as arthrosis, organs and so on. A novel finite element model of the entire human skeletal system was proposed in this paper. As far as we know, there is no similar reports yet. First, the anatomical detailed three-dimension models of human musculoskeletal system were reconstructed from the cross-sectional images of China Visible Human Project. Second, the sectional finite element models of musculoskeletal system was built. And, the finite element model of the entire human musculoskeletal system was integrated. In the end, a weightlifting motor task simulation was implemented as a case study using the proposed method on supercomputer platform Dawning4000A in Shanghai Supercomputer Center. The muscle forces and the skeleton stresses of subject during weightlifting locomotion were obtained. Based on these parameters, the locomotion ability of subject was evaluated. It was validated that the proposed method could provide the inbeing biomechanical information of musculoskeletal system in vivo. Furthermore, it could evaluate human locomotion ability based on these information from a novel viewpoint.