Matching Items (13)
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- All Subjects: Biomedical
- Creators: Harrington Bioengineering Program
- Creators: Kodibagkar, Vikram
Description
A direct Magnetic Resonance (MR)-based neural activity mapping technique with high spatial and temporal resolution may accelerate studies of brain functional organization.
The most widely used technique for brain functional imaging is functional Magnetic Resonance Image (fMRI). The spatial resolution of fMRI is high. However, fMRI signals are highly influenced by the vasculature in each voxel and can be affected by capillary orientation and vessel size. Functional MRI analysis may, therefore, produce misleading results when voxels are nearby large vessels. Another problem in fMRI is that hemodynamic responses are slower than the neuronal activity. Therefore, temporal resolution is limited in fMRI. Furthermore, the correlation between neural activity and the hemodynamic response is not fully understood. fMRI can only be considered an indirect method of functional brain imaging.
Another MR-based method of functional brain mapping is neuronal current magnetic resonance imaging (ncMRI), which has been studied over several years. However, the amplitude of these neuronal current signals is an order of magnitude smaller than the physiological noise. Works on ncMRI include simulation, phantom experiments, and studies in tissue including isolated ganglia, optic nerves, and human brains. However, ncMRI development has been hampered due to the extremely small signal amplitude, as well as the presence of confounding signals from hemodynamic changes and other physiological noise.
Magnetic Resonance Electrical Impedance Tomography (MREIT) methods could have the potential for the detection of neuronal activity. In this technique, small external currents are applied to a body during MR scans. This current flow produces a magnetic field as well as an electric field. The altered magnetic flux density along the main magnetic field direction caused by this current flow can be obtained from phase images. When there is neural activity, the conductivity of the neural cell membrane changes and the current paths around the neurons change consequently. Neural spiking activity during external current injection, therefore, causes differential phase accumulation in MR data. Statistical analysis methods can be used to identify neuronal-current-induced magnetic field changes.
The most widely used technique for brain functional imaging is functional Magnetic Resonance Image (fMRI). The spatial resolution of fMRI is high. However, fMRI signals are highly influenced by the vasculature in each voxel and can be affected by capillary orientation and vessel size. Functional MRI analysis may, therefore, produce misleading results when voxels are nearby large vessels. Another problem in fMRI is that hemodynamic responses are slower than the neuronal activity. Therefore, temporal resolution is limited in fMRI. Furthermore, the correlation between neural activity and the hemodynamic response is not fully understood. fMRI can only be considered an indirect method of functional brain imaging.
Another MR-based method of functional brain mapping is neuronal current magnetic resonance imaging (ncMRI), which has been studied over several years. However, the amplitude of these neuronal current signals is an order of magnitude smaller than the physiological noise. Works on ncMRI include simulation, phantom experiments, and studies in tissue including isolated ganglia, optic nerves, and human brains. However, ncMRI development has been hampered due to the extremely small signal amplitude, as well as the presence of confounding signals from hemodynamic changes and other physiological noise.
Magnetic Resonance Electrical Impedance Tomography (MREIT) methods could have the potential for the detection of neuronal activity. In this technique, small external currents are applied to a body during MR scans. This current flow produces a magnetic field as well as an electric field. The altered magnetic flux density along the main magnetic field direction caused by this current flow can be obtained from phase images. When there is neural activity, the conductivity of the neural cell membrane changes and the current paths around the neurons change consequently. Neural spiking activity during external current injection, therefore, causes differential phase accumulation in MR data. Statistical analysis methods can be used to identify neuronal-current-induced magnetic field changes.
ContributorsFu, Fanrui (Author) / Sadleir, Rosalind (Thesis advisor) / Kodibagkar, Vikram (Committee member) / Kleim, Jeffrey (Committee member) / Muthuswamy, Jitendran (Committee member) / Helms Tillery, Stephen (Committee member) / Arizona State University (Publisher)
Created2019
Description
Spasticity is a neurological disorder in which a target group of muscles remain in a contracted state. In addition to interfering with the function of these muscles, spasticity causes chronic pain and discomfort. Often found in patients with cerebral palsy, multiple sclerosis, or stroke history, spasticity affects an estimated twelve million people worldwide. Not only does spasticity cause discomfort and loss of function, but the condition can lead to contractures, or permanent shortenings of the muscle and connective tissue, if left untreated. Current treatments for spasticity are primarily different forms of muscle relaxant pharmaceuticals. Almost all of these drugs, however, carry unwanted side effects, including total muscle weakness, liver toxicity, and possible dependence. Additionally, kinesiotherapy, conducted by physical therapists at rehabilitation clinics, is often prescribed to people suffering from spasticity. Since kinesiotherapy requires frequent practice to be effective, proper treatment requires constant professional care and clinic appointments, discouraging patient compliance. Consequently, a medical device that could automate relief for spasticity outside of a clinic is desired in the market. While a number of different dynamic splints for hand spasticity are currently on the market, research has shown that these devices, which simply brace the hand in an extended position, do not work through any mechanism to decrease spastic tension over time. Two methods of temporarily reducing spasticity that have been observed in clinical studies are cryotherapy, or the decrease of temperature on a target area, and electrotherapy, which is the delivery of regulated electrical pulses to a target area. It is possible that either of these mechanisms could be incorporated into a medical device aimed toward spastic relief. In fact, electrotherapy is used in a current market device called the SaeboStim, which is advertised to help stroke recovery and spastic reduction. The purpose of this paper is to evaluate the viability of a potential spastic relief device that utilizes cryotherapy to a current and closest competitor, the SaeboStim. The effectiveness of each device in relieving spasticity is reviewed. The two devices are also compared on their ability to address primary customer needs, such as convenience, ease of use, durability, and price. Overall, it is concluded that the cryotherapy device more effectively relieves hand spasticity in users, although the SaeboStim's smaller size and better convenience gives it market appeal, and reveals some of the shortcomings in the preliminary design of the cryotherapy device.
ContributorsWiedeman, Christopher Blaise (Author) / Kleim, Jeffrey (Thesis director) / Buneo, Christopher (Committee member) / W.P. Carey School of Business (Contributor) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Volume depletion can lead to migraines, dizziness, and significant decreases in a subject's ability to physically perform. A major cause of volume depletion is dehydration, or loss in fluids due to an imbalance in fluid intake to fluid excretion. Because proper levels of hydration are necessary in order to maintain both short and long term health, the ability to monitor hydration levels is growing in clinical demand. Although devices capable of monitoring hydration level exist, these devices are expensive, invasive, or inaccurate and do not offer a continuous mode of measurement. The ideal hydration monitor for consumer use needs to be characterized by its portability, affordability, and accuracy. Also, this device would need to be noninvasive and offer continuous hydration monitoring in order to accurately assess fluctuations in hydration data throughout a specified time period. One particular method for hydration monitoring that fits the majority of these criteria is known as bioelectric impedance analysis (BIA). Although current devices using BIA do not provide acceptable levels of accuracy, portability, or continuity in data collection, BIA could potentially be modified to fit many, if not all, desired customer specifications. The analysis presented here assesses the viability of using BIA as a new standard in hydration level measurement. The analysis uses data collected from 22 subjects using an existing device that employs BIA. A regression derived for estimating TBW based on the parameters of age, weight, height, sex, and impedance is presented. Using impedance data collected for each subject, a regression was also derived for estimating impedance based on the factors of age, weight, height, and sex. The derived regression was then used to calculate a new impedance value for each subject, and these new impedance values were used to estimate TBW. Through a paired-t test between the TBW values derived by using the direct measurements versus the calculated measurements of impedance, the two samples were found to be comparable. Considerations for BIA as a noninvasive measurement of hydration are discussed.
ContributorsTenorio, Jorge Antonio (Author) / LaBelle, Jeffrey (Thesis director) / Pizziconi, Vincent (Committee member) / Spano, Mark (Committee member) / Barrett, The Honors College (Contributor) / W. P. Carey School of Business (Contributor) / Harrington Bioengineering Program (Contributor)
Created2013-05
Description
The action/adventure game Grad School: HGH is the final, extended version of a BME Prototyping class project in which the goal was to produce a zombie-themed game that teaches biomedical engineering concepts. The gameplay provides fast paced, exciting, and mildly addicting rooms that the player must battle and survive through, followed by an engineering puzzle that must be solved in order to advance to the next room. The objective of this project was to introduce the core concepts of BME to prospective students, rather than attempt to teach an entire BME curriculum. Based on user testing at various phases in the project, we concluded that the gameplay was engaging enough to keep most users' interest through the educational puzzles, and the potential for expanding this project to reach an even greater audience is vast.
ContributorsNitescu, George (Co-author) / Medawar, Alexandre (Co-author) / Spano, Mark (Thesis director) / LaBelle, Jeffrey (Committee member) / Guiang, Kristoffer (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
Description
As the rates of anxiety in adults rapidly swell, new and creative treatment methods become increasingly relevant. Individuals with an anxiety disorder may experience challenging symptoms that interfere with daily activities and impede academic and social success. The purpose of this project is to design and engineer a portable heart rate monitor that communicates with an iOS mobile application for use by individuals suffering from anxiety or panic disorders. The proposed device captures the innovation of combining biosensor feedback with new, creative therapy methods on a convenient iOS application. The device is implemented as an Arduino Uno which translates radial pulse information onto an LCD screen from a wristband. Additionally, the iOS portion uses a slow expanding and collapsing animation to guide the user through a calming breathing exercise while displaying their pulse in beats per minute. The user's awareness or his or her ability to control one's own physiological state supports and facilitates an additional form of innovative therapy. The current design of the iOS app uses a random-number generator between 40 to 125 to imitate a realistic heart rate. If the value is less than 60 or greater than 105, the number is printed in red; otherwise the heart rate is displayed in green. Future versions of this device incorporate bluetooth capabilities and potentially additional synchronous methods of therapy. The information presented in this research provides an excellent example of the integrations of new mobile technology and healthcare.
ContributorsTadayon, Ramesh (Author) / Muthuswamy, Jit (Thesis director) / Towe, Bruce (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Engineers have a strong influence on everyday lives, ranging from electronics and trains to chemicals and organs [1]. However, in the United States, there is a large knowledge gap in the roles of engineers, especially in K-12 students [2] [3]. The National Academy of Engineering (NAE) recognizes the current problems in engineering, such as the dominance of white males in the field and the amount of education needed to become a successful engineer [4]. Therefore, the NAE encourages that the current engineering community begin to expose the younger generations to the real foundation of engineering: problem-solving [4]. The objective of this thesis is to minimize the knowledge gap by assessing the current perception of engineering amongst middle school and high school students and improving it through engaging and interactive presentations and activities that build upon the students’ problem-solving abilities.
The project was aimed towards middle school and high school students, as this is the estimated level where they learn biology and chemistry—key subject material in biomedical engineering. The high school students were given presentations and activities related to biomedical engineering. Additionally, within classrooms, posters were presented to middle school students. The content of the posters were students of the biomedical engineering program at ASU, coming from different ethnic backgrounds to try and evoke within the middle school students a sense of their own identity as a biomedical engineer. To evaluate the impact these materials had on the students, a survey was distributed before the students’ exposure to the materials and after that assesses the students’ understanding of engineering at two different time points. A statistical analysis was conducted with Microsoft Excel to assess the influence of the activity and/or presentation on the students’ understanding of engineering.
The project was aimed towards middle school and high school students, as this is the estimated level where they learn biology and chemistry—key subject material in biomedical engineering. The high school students were given presentations and activities related to biomedical engineering. Additionally, within classrooms, posters were presented to middle school students. The content of the posters were students of the biomedical engineering program at ASU, coming from different ethnic backgrounds to try and evoke within the middle school students a sense of their own identity as a biomedical engineer. To evaluate the impact these materials had on the students, a survey was distributed before the students’ exposure to the materials and after that assesses the students’ understanding of engineering at two different time points. A statistical analysis was conducted with Microsoft Excel to assess the influence of the activity and/or presentation on the students’ understanding of engineering.
ContributorsLlave, Alison Rose (Author) / Ganesh, Tirupalavanam (Thesis director) / Parker, Hope (Committee member) / Harrington Bioengineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Transcranial electrical stimulation (tES) is a non-invasive brain stimulation therapy that has shown potential in improving motor, physiological and cognitive functions in healthy and diseased population. Typical tES procedures involve application of weak current (< 2 mA) to the brain via a pair of large electrodes placed on the scalp. While the therapeutic benefits of tES are promising, the efficacy of tES treatments is limited by the knowledge of how current travels in the brain. It has been assumed that the current density and electric fields are the largest, and thus have the most effect, in brain structures nearby the electrodes. Recent studies using finite element modeling (FEM) have suggested that current patterns in the brain are diffuse and not concentrated in any particular brain structure. Although current flow modeling is useful means of informing tES target optimization, few studies have validated tES FEM models against experimental measurements. MREIT-CDI can be used to recover magnetic flux density caused by current flow in a conducting object. This dissertation reports the first comparisons between experimental data from in-vivo human MREIT-CDI during tES and results from tES FEM using head models derived from the same subjects. First, tES FEM pipelines were verified by confirming FEM predictions agreed with analytic results at the mesh sizes used and that a sufficiently large head extent was modeled to approximate results on human subjects. Second, models were used to predict magnetic flux density, and predicted and MREIT-CDI results were compared to validate and refine modeling outcomes. Finally, models were used to investigate inter-subject variability and biological side effects reported by tES subjects. The study demonstrated good agreements in patterns between magnetic flux distributions from experimental and simulation data. However, the discrepancy in scales between simulation and experimental data suggested that tissue conductivities typically used in tES FEM might be incorrect, and thus performing in-vivo conductivity measurements in humans is desirable. Overall, in-vivo MREIT-CDI in human heads has been established as a validation tool for tES predictions and to study the underlying mechanisms of tES therapies.
ContributorsIndahlastari, Aprinda (Author) / Sadleir, Rosalind J (Thesis advisor) / Abbas, James (Committee member) / Frakes, David (Committee member) / Kleim, Jeffrey (Committee member) / Kodibagkar, Vikram (Committee member) / Arizona State University (Publisher)
Created2017
Description
Compressed sensing magnetic resonance spectroscopic imaging (MRSI) is a noninvasive and in vivo potential diagnostic technique for cancer imaging. This technique undersamples the distribution of specific cancer biomarkers within an MR image as well as changes in the temporal dimension and subsequently reconstructs the missing data. This technique has been shown to retain a high level of fidelity even with an acceleration factor of 5. Currently there exist several different scanner types that each have their separate analytical methods in MATLAB. A graphical user interface (GUI) was created to facilitate a single computing platform for these different scanner types in order to improve the ease and efficiency with which researchers and clinicians interact with this technique. A GUI was successfully created for both prospective and retrospective MRSI data analysis. This GUI retained the original high fidelity of the reconstruction technique and gave the user the ability to load data, load reference images, display intensity maps, display spectra mosaics, generate a mask, display the mask, display kspace and save the corresponding spectra, reconstruction, and mask files. Parallelization of the reconstruction algorithm was explored but implementation was ultimately unsuccessful. Future work could consist of integrating this parallelization method, adding intensity overlay functionality and improving aesthetics.
ContributorsLammers, Luke Michael (Author) / Kodibagkar, Vikram (Thesis director) / Hu, Harry (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Nerve endings are particularly difficult to target during peripheral nerve block (PNB) procedures, so ultrasound-guided needles are of immense importance to guarantee safe and efficient delivery of the anesthetic to the target nerve. Despite significant progress in needle visualization with ultrasound imaging, there are still several factors that lead to poor needle visibility, the main factor being insertion angle. Introducing cavities and holes in the needle at specific intervals through pitting corrosion may alter the ultrasonic feedback from the sensor, thereby resulting in improved clarity of the reconstructed image. The purpose of this experiment is to investigate the effectiveness of two novel pitting designs on the needle’s visibility under ultrasound. Two different designs and two depths of cut are tested in a 22 factorial that is blocked by insertion angle: a uniform and a non-uniform design. Needles were cut using a Plain Jane and Igor laser cutter and imaged using a GE Logig e BT12 ultrasound imaging machine. Images were compared visually and objectively by using a tool in Photoshop to calculate the luminosity of the needle. Two videos were also taken capturing the difficulty of imaging surgical needles. Results showed that pitting had a major impact on needle visibility at 30° and a marginal impact at 0°. The videos supported these results as it was considerably more difficult to locate the control needle than the experimental needle. This suggests the probe must be in a specific plane with the control needle for it to be visible while the experimental needle is much more lenient. Results from the two depths of cuts showed similar results in that the designs which were cut twice were more visible than their counterparts at 30°. The study showed that pitting has positive effects on needle visibility; it improves visibility by increasing the luminescence of the needle and by decreasing its sensitivity to probe position.
ContributorsTze, David (Author) / Muthuswamy, Jit (Thesis director) / Towe, Bruce (Committee member) / Harrington Bioengineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
NIPAAm co-DEAEMA hydrogels are a potential solution for sustained, local delivery of ketorolac tromethamine. Current methods of postoperative pain management, such as local anesthetics, NSAIDs, and opioids, can be improved by minimizing side effects while still effectively treating severe and extreme pain. Though high doses of ketorolac can be toxic, sustained, local delivery via hydrogels offers a promising solution. Four ketorolac release studies were conducted using PNDJ hydrogels formulated by Sonoran Biosciences. The first two studies tested a range of JAAm concentration between 1.4 and 2.2 mole percent. Both had high initial release rates lasting less than 7 days and appeared to be unaffected by JAAm content. Tobramycin slowed down the release of ketorolac but was unable to sustain release for more than 6 days. Incorporating DEAEMA prolonged the release of ketorolac for up to 14 days with significant reductions in initial burst release rate. Low LCST of NIPAAM co-DEAEMA polymer is problematic for even drug distribution and future in vivo applications.
ContributorsHui, Nathan (Author) / Vernon, Brent (Thesis director) / Heffernan, John (Committee member) / School of International Letters and Cultures (Contributor) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05