Biomedical Engineering: Applications, Basis and Communications

Contrast agents are used in 30–40% of diagnostic MRI scans. These agents are expensive and cause adverse effects in some patients. One way to reduce the amount of contrast agent needed would be to improve the signal-to-noise ratio (SNR). We hypothesized that pre-magnetizing samples of the paramagnetic contrast agent gadodiamide before scanning would increase the SNR. Samples of gadodiamide in saline were magnetized with a permanent magnet before being placed in a phantom and scanned in either a closed 1.5 T MRI or an open 0.35 T MRI. Samples were scanned 0–5 hours after magnetization. Samples of gadodiamide that had not been magnetized were also scanned. In the 1.5 T instrument, we found an increase in SNR in pre-magnetized samples that was highest three hours after magnetization, up to a 1.8-fold increase at low concentrations of gadodiamide. The improvement in SNR was more modest in the low-field MRI scanner, peaking two hours after magnetization. This relatively simple method has the potential to reduce the amount of contrast agents needed for diagnostic MRI scans.

Music therapy is a common approach to reduce stress and anxiety levels. To examine the effect of different types of music on stress levels, forty Generalized Anxiety Disorder (GAD) patients were assigned randomly to one of four groups exposed to a specific kind of music described in this research. The electroencephalogram (EEG) was recorded from Cz placement along with skin conductance and temperature recordings for each subject. Also, commonly used clinical questionnaires were used to determine the patients, stress levels. In the classical music group, significant increments in the alpha relative power occurred. Additionaly, in the preferred music group, the relative power of the beta EEG rhythm significantly decreased. These results were compatible with clinical results. Our study showed that music therapy for GAD patients could be used as a powerful method to reduce stress and anxiety. Furthermore, the skin conductance is analyzed and incremental increase in two groups is observed.

Testing objects are important for the validation of developing biopsy systems. Unfortunately, they are very hard to obtain. Motivated by this issue, the purpose of this study is to develop a technique for the easy creation of a model to simulate tumors of different sizes inside porcine livers, which could be used for ultrasound image-guided liver biopsy amongst other applications, and evaluate its performance by comparing to the more widely-used approaches in-vivo and ex-vivo. In this study, a Vaseline-based tumor model, and a more widely-used agar-based tumor model to provide comparison with the proposed method were created and injected into porcine livers as biopsy targets. The clinician located simulated tumors using real-time 2D imaging under the guidance of a robotic arm to delivery the biopsy in ex-vivo and in-vivo experiments. The results show that the optimum tumor model was created from a mixture of Vaseline, glycerol, and barium sulfate which can be easily produced and injected. All Vaseline-based simulated tumors were of solid, palpable mass on gross examination, and ultrasound imaging revealed clearly visible lesions. The clinician successfully performed ultrasound image guided liver biopsy in all the trials (10/10) in the ex-vivo experiment, and 2 out of 3 trials (2/3) in the in-vivo experiment on this optimum tumor model. We described a novel technique of creating solid liver tumor models that can be used for ultrasound image-guided liver biopsy.

The VIWA system has been developed to provide computer access for paralyzed people. The system detects the users’ breath pressure with an electrical board and translates it to the location coordinates in computer display screen. The user navigates mouse cursor by specifying the coordination of x and y. A graphical keyboard has been designed to provide text-entry ability with text-to-speech embedded feature. The system is platform-independent and can be run in every client side devices.

A group of 10 people without disabilities tested the VIWA and quickly learned how to use it to spell out messages or interact with computer. Ten people with disabilities also tried the system. The measured mistakes and time are showing that the user is capable to control the mouse cursor with the accuracy of 99.8%. The average time of experiment shows that users can reach their speed of writing to 7.9 words/min after two attempts.

There is a need for new methods to measure the level of arterial stiffness easily at home. A previous report investigating the effect of measurement position on brachial–ankle pulse wave velocity (baPWV) showed that baPWV was higher in the sitting position than in the supine position. This was probably because the increased ankle PWV was associated with increased hydrostatic pressure in the arteries of lower extremities. Therefore, we investigated the effect of measurement position on the cardio-ankle vascular index (CAVI), which is hardly affected by blood pressure. CAVI was measured in 50 healthy males (20–74 years) in five positions: supine, sitting, sitting with the knees flexed at 0${}^{\circ }$, reclining 50${}^{\circ }$, and standing. Compared to other positions, CAVI in the supine position was the lowest ($P<0.01$); $t_{\mathrm{\text{b}}}$ (the time difference between the second heart sound and the notch of the pulse wave in the upper arm) in the supine position was the highest ($P<0.01$); and $t_{\mathrm{\text{ba}}}$ (the time difference between the minimum upper arm and ankle pulse wave pattern values) in the supine position was the highest ($P<0.01$). Thus, our results indicated that changes in measurement position reduced pulse arrival time (increasing pulse wave velocity). We also observed a good correlation between CAVI in the supine position and that in other positions. The present study showed that the measurement position affected CAVI as much as it affected baPWV. Accordingly, correcting for the measurement position would be required when the position differs from supine.

Poincar section is a tool used in analysis and even control of non-linear systems like chaotic and uncertain systems. Although it has been presented long ago, yet this approach is artistic and heuristic. Poincar Section is destitute of any definite methodologies and problems including indefinite structure and model parameters that can be generally attributed to this approach; machine learning based on Poincar section is impossible. In this article, first of all, signal modeling steps using Poincar is explained, then considering the occurred events, the concept of information and relativism applying Poincar section and information approach, we will diagnose the brain pattern variations in Autistic cases. The reason we have taken Autism into consideration is because we believe its origin is information, in other words the big problem in Autism disorder is software kind, which can lead to hardware kind over time.

In this research a new kind of representation, namely Extended Complementary Plot, in which the main characteristic is special attention to signal phase as embedded information in the signal and ineffectiveness of energy, is introduced. All the introduced state-of-art concepts on Electroencephalography are implemented on Autistic children. Recording the EEG signal in Autistic children has always been a challenge for the specialists. Implementations of the article have been carried out on over 120 cases including 60 Autistic children and 60 normal ones ranging from 3 to 10 years old, in three different states; asleep, open eyes and a new record based on brain dynamics which has been suggested from the authors and does not have the other records problems for Autistic kids.

Prodigious results accomplished, suggests the common dynamic presence in Autism disorder which is entirely different from normal dynamics, and this is only due to the potency of the applied information tool; Poincar section, and cybernetic modeling in this research. We hope that the empirical results of this research to be a strong and effective step towards quantification of Autism disorder and conversion of diagnosis process from Clinical to Para clinical, and even early Autism diagnosis.

Prolonged standing is related to various health problems such as lower back pain and lower extremity discomfort. This study was to investigate the effects of prolonged standing on posture control and whether the sloped surface is beneficial to adults who are required to stand for a long period of time. Twenty young healthy adults (age: $20.5\pm 0.8$ years, height: $165.2\pm 8.5$ cm, weight: $56.6\pm 9.6$ kg, 6 males and 14 females) participated in this study. They were asked to perform a sixty-second quiet-standing evaluation first (i.e. the pre-test condition), then the thirty-minute standing test, and followed by the sixty-second standing test again (i.e. the post-test condition). They stood barefoot quietly on a force plate watching a video on television located 2 m ahead. Three sloped conditions, i.e. the level ground, inclined (with the ankle dorsiflexed), and declined (with the ankle plantarflexed), were randomly examined on separate days. The trajectory, maximal anteroposterior/mediolateral displacement, sway area, and complexity index (CI) of the center of pressure (CoP) during the standing tests were analyzed. Ten-point visual analogue scale (VAS) for perceived fatigue was also recorded. One-way ANOVA and paired t-test were used to analyze postural changes among sloped conditions before and after the prolonged standing.

Signs of fatigue (VAS were $4.1\pm 1.9$, $4.6\pm 1.3$ and $3.5\pm 1.5$ for the level, inclined, and declined conditions, respectively) and significant increases in all CoP measures for the three slope conditions after thirty minutes of standing (all $p<0.05$) were noted. Trajectory was greatest under inclined, followed by the declined and level conditions ($p<0.05$). The CI was generally greater under the declined surface than the level and inclined surfaces along with the thirty-minute standing.

These findings indicated that prolonged standing resulted in fatigue and increased postural changes, particularly on the inclined surface. A greater complexity on the declined surface implied that participants had better adaptability while standing on a declined surface than a flat or inclined surface. Current findings suggested that a declined surface could be a suitable choice for a prolonged standing and further studies are warranted to evaluate its efficacy on different career workers.

Simulation of heart and particularly heart valves is amongst the most common and fundamental methods in diagnosis and treatment of heart disorders. Replacement of natural valves with prosthetic valves is a prevalent treatment to valvular damages. The idea of using tissue engineering heart valves is in progress in developing countries. This is because of their unique biocompatibility and biodegradability according to special characteristics and geometries of every single patient’s heart. By considering and changing specific parameters for optimization of valve design, one can obtain the most favorable dimensions of the scaffold. So far, there are various studies which have been focused on leaflet stress distribution and deformation, but considering the blood in these studies have been less taken into account. Excellence of considering fluid structure interaction is to provide real physiological condition for heart valve simulation. Simulation of bioprosthetic heart valve with 19mm diameter for various geometries of leaflets was performed. Hemodynamic parameters such as mean velocity, flow rate, transvalvular pressure drop, effective orifice area, wall shear stresses, and structural parameters like Von Mises were investigated. Results indicated that leaflet with 12mm height among other geometries is the best case for hemodynamic parameters and Von Mises stress.