Biomedical Engineering: Applications, Basis and Communications

In order to present a systematic and practical approach that uses high-resolution computed tomography (HRCT) to derive models of the middle ear for finite element analysis (FEA). This prospective study included 31 subjects with normal hearing and no previous otological disorders. Temporal bone images obtained from 15 right ears and 16 left ears were used for evaluation and reconstruction. High-resolution computed tomography of temporal bone was performed using simultaneous acquisition of 16 sections with a collimated slice thickness of 0.625 mm. All images were transferred to an Amira visualization system for 3D reconstruction. The created 3-D model was translated into two commercial modeling packages, Patran and ANSYS, for finite element analysis. The characteristic dimensions of the model were measured and compared with previous published histological section data. This result confirms that the geometric model created by the proposed method is accurate except the tympanic membrane is thicker than that of histological section method. No obvious difference in the geometrical dimension between right and left ossicles was found (p > 0.05). The 3D model created by finite element method and predicted umbo and stapes displacements are close to the bounds of the experimental curves of Nishihara's, Huber's, and Gan's data across the frequency range of 100-8000 Hz. The model includes a description of the geometry of the middle ear components, and dynamic equations of vibration. The proposed method is quick, practical, low cost and most importantly, non-invasive as compared with histological section methods.

Poly N-isopropylacrylamide (PNIPAAm) is a well-known temperature-sensitive polymer. When the temperature is higher than the lower critical solution temperature (LCST), PNIPAAm aquous solution is cloudy (phase separation occurred). In contrast, when the temperature is lower than the LCST, PNIPAAm is soluble in water (a homogeneous solution). The lower critical solution temperature (LCST) in aqueous solution of PNIPAAm was about 32~33°C. We prepared nano-scaled PNIPAAm particles containing carboxylic group on their surfaces by introducing acrylic acid monomer. The carboxylic groups were applied to conjugate with the amino group of the CD34 antibody. This immuno-conjugate can be applied on targeting the human CD34 positive cells, peripheral blood progenitor cells included, for cell purification and drug controlled release. In order to the active responding of controlled release of the conjugate in the body influenced by temperature, we hope to estimate the shifting of the gel-collapse temperature or cloud point of the immuno-conjugates by dynamic light scattering (DLS) and UV absorption. The results show that the gel-collapse temperature of the nano-particle was not significantly affected by the content of AA between 1.5~5 mol%. However, cloud point of the solution was elevated by the conjugation of CD34 antibody to 37°C. When CD34-conjugated particle was subsequently incorporated with recombinant FLT3-ligand, which is a smaller molecule compare to CD34 antibody, cloud point of the solution was not affected.

This paper describes a haptic device equipped surgical simulator that provides visual and haptic responses for amputation surgery. This simulator, based on our reported volume (constituted from CT slices) manipulation algorithms, can compute and demonstrate bone changes for the procedures in various orthopedic surgeries. The system is equipped with a haptic device. The position and attitude the haptic device are transformed into the volume to simulate and render the oscillating virtual saw together with the virtual bones. The system then judges if every saw tooth immersing in (cutting) any bone. The load for removing the bone chip on a cutting tooth is calculated according to the feed rate, oscillating speed, saw geometry and bone type. The loads on all the saw teeth are then summed into the three positional forces that the haptic device generates and thus the user feels. The system provides real-time visual and haptic refresh speeds for the sawing procedures. A simulation example of amputation surgery demonstrates the sawing haptic and visual feelings of the sawing procedure are consistent and the simulated sawing force resembles the real force. Therefore, this prototype simulator demonstrates the effectiveness as a surgical simulator to rehearsal the surgical procedures, confirm surgical plains and train interns and students.

The quality of traditional two-dimensional image reconstruction for PET has been efficiently improved by three-dimensional image reconstruction, but the sensitivity of the data and the quality of the image are restricted by the limit of modality physics. In analytical image reconstruction algorithm, 3DRP method compensates the unmeasured events by forward projection based on the initial direct image estimate. However, the original 3DRP method merely depends on the parallel projections without taking into account the oblique projections. In our proposed 3DRP-SSRB method, we improve the first image estimate by incorporating the rebinned oblique data. SSRB method was used to perform the rebinning operation to make uses of the oblique projection data to improve the sensitivity information. And then project the improved image estimate forward and reconstruct the final image. Conflicting parameters of reconstructed image quality of 3DRP are experimented by simulated three-dimensional phantom study with regard to both system sensitivity and image quality factors. PET simulation software package was used to conduct the experiment along with the MATLAB software to evaluate the effectiveness of two-dimensional FBP, 3DRP, and our proposed 3DRP-SSRB methods. The result demonstrated its better image quality by having better mean squared error numbers in most of output image slices.

Capsule endoscopy gradually replaces traditional endoscopy in some applications and becomes a state-of-the-art tool to detect the problems of intestines. When capsule endoscopy is used, a patient swallows a capsule-like micro-camera. An image sequence is then taken by the capsule endoscope and transmitted to a receiver carried by the patient. Eventually, these image data will be transmitted to a desktop computer and examined by a doctor. To start the diagnosis earlier and avoid limiting the patient's movement, an on-line wireless transmission for this last link is desirable. For this link, WLAN (Wireless Local Area Network) standard is a good candidate due to its high enough data rate and commercial availability. However, wireless links often result in transmission errors that are unacceptable for medical related applications, including medical image transmission. In this paper, we propose a WLAN system with smart antenna to transmit the capsule endoscope images and evaluate its performance. The simulation results demonstrate that utilizing the smart antenna can enhance the error resilient capability of the WLAN over an error prone wireless channel and provides a much reliable data link for the transmission of capsule endoscope images than the original standard.

Control strategies are the chief attraction in the field of rehabilitation engineering, and especially in a functional electrical stimulation (FES) system, a reliable control method is important for paralyzed patients to restore lost their functions. In this paper, we have presented a demonstration of the control strategy, which is based on the patient-driven loop, used in a non-invasive FES system for hand function restoration. With the patient-driven loop control, hemiplegic patients could use their residual capabilities, such as shoulder movements in their sound extremities, the myoelectric signals generated from different muscles, etc, to operate the FES system. Here we have chosen the most common and acceptable signals as the input sources, i.e. electromyographic (EMG) signals, to control a non-invasive FES system, generating the electrical stimuli to excite the paralyzed muscles. In addition, EMG signals recorded by the sensors in the electrical stimulator can serve both as the trigger of the system and as the adjustment of the electrical stimulation parameters, thereby improving the system's performance and reliability. From the experimental results, subjects can successfully use their residual capabilities to control the FES system and restore their lost hand functions as well. On the other hand, from the viewpoints of rehabilitation and psychology, hemiplegics will benefit greatly by using their residual capabilities to regain their lost functions. It is believed that the patient-driven loop control is very useful, not only for the FES system in this study, but also for other assistive devices. By the control strategy proposed in this paper, we deeply hope that patients will benefit greatly and regain their self-confidence.

Simultaneous dual-isotope imaging has contributions from two different energy gamma rays, such as Tc-99m (140KeV) and I-123 (159KeV). Dual-isotope Tc-99m/I-123 imaging has capability in nuclear medicine applications for brain perfusion or presynaptic and postsynaptic dopamine system and for myocardial perfusion system. It reduces acquisition time and makes registration much easier. But the disadvantages of dual-isotope technique are the scatter and cross-talk between the two emitted gamma-ray photons. We proposed a new method to correct for cross-talk from primary and scattered photons using independent component analysis (ICA), which was compared to conventional energy-window method (CONW). In this paper we investigated the performance of ICA to separate Tc-99m and I-123 energy spectra from dual-isotope simulated data to obtain images of each isotope. In Tc-99m images, the estimated image was extracted from mixed dual-isotope imaging using ICA with the percentage bias (P) about -11% and the mean square error (MSE) of 80.48. The counts of Tc-99m were overestimated by CONW method with P < 66% and MSE of 1860.28. ICA could reduce the contamination significantly from I-123 to Tc-99m window. In I-123 images, the cross-talk was disappeared in both methods, but the percentage bias for ICA (< -18%) was less than that of CONW (< -57%). The MSE was 104.63 for the ICA case and 960.15 for the CONW case. The results demonstrated that ICA method improved the quantitative accuracy and can be a promising and effective tool for dual-isotope imaging.

Purpose: Cone-beam micro computed tomography CT (micro-CT) can offer comprehensive 3D information and high-resolution images. This technology can be used with other imaging modalities in the preclinical application of molecular imaging research. Image reconstruction algorithm affects final image spatial resolution, which is the primary topic of this study. We use two types of reconstruction methods, which are analytical (tent-FDK) and statistical iterative (convex algorithm) algorithms, to reconstruct the micro-CT images for evaluation. Materials and Methods: In this study, projection data of the Defrise phantom and HA (Hydroxy-Apatite) phantom were obtained using an in-house designed micro-CT imaging system and images were reconstructed with the tent-FDK and convex algorithms. We develop a new way to calculate the system matrix of our micro-CT. Human tooth sample and mouse bone sample data were reconstructed with the analytic and iterative algorithms. Results: The Defrise phantom results show coronal view of the images reconstructed by the tent-FDK and convex algorithms. From the profile of the results, image reconstructed by the convex algorithm has higher pixel value in the high-density layer. Comparison of the results of human tooth sample and mouse bone sample reconstructed by the two kinds of algorithms, the image reconstructed by the convex algorithm has fewer artifacts and more correct pixel value representing for the attenuation coefficients. Conclusion: Tent-FDK algorithm is a kind of useful analytic method to reconstruct cone-beam CT data. We also develop the convex iterative method to reconstruct images for low dose X-ray cone-beam CT, which performs better than the analytical one in general.