Use of an Impedance Tube to determine the effect of Falx Cerebri on MRE Readings
Use of an Impedance Tube to determine the effect of Falx Cerebri on MRE readings
March 8, 2018
Kurt Lab at Stevens Institute of Technology, 1 Castle Point Terrace, Hoboken, NJ
Luca Conetta Mentors:Dr. Mehmet Kurt and Efe Ozkaya
March 8, 2018
Kurt Lab at Stevens Institute of Technology, 1 Castle Point Terrace, Hoboken, NJ
Luca Conetta Mentors:Dr. Mehmet Kurt and Efe Ozkaya
Abstract:
The brain is one of the most important and delicate organs of the human anatomical system. It is these characteristics that lead scientists to devise newer and improved ways of detecting and fixing problems within the brain. The downsides with traditional methods of detecting anomalies within the human body is that when they are applied to the brain, they can have an extremely detrimental effects. Techniques such as X-Ray and PET, and MRI, which use radiation and magnetism respectively, are unpredictable when it come to the brain and have a chance of severely damaging cognitive functions. This proposed project will seek to determine the effect of specific parts of the brain upon specific proven non-invasive techniques used in the detection of brain tumors and other irregularities. There is limited research in this specific field, and thus this work will be important in determining the applicability of certain methods. This project will test the effect that the Falx Cerebri has on Magnetic Resonance Elastography actuator measurements, as well as the effect angular orientation has on the readings taken by this device. The overarching goal is determine the effects that certain conditions have on the effectiveness of Magnetic Resonance Elastography actuators in detecting brain tumors and other harmful anomalies.
Background:
Magnetic Resonance Elastography (MRE) is a non-invasive method for quantifying the mechanical properties of tissue in the brain (Mariappan et al., 2010). It functions by vibrating upon the surface of the head, creating shear waves which harmlessly pass through brain tissue, then taking magnetic resonance images of said shear waves using an MRI machine and analysing them to detect any potential anomalies in the brain (Uffman, 2002). It is an extremely promising technique which can be used to detect anomalies in brain tissue earlier rather than later (Hiscox, 2016). However, different structures within the brain can affect the way that these waves move. One of these structures, the Falx Cerebri, is a curved plate of hard dura matter(one of the substances that helps protect the brain) that runs through the center of the brain, separating the left and right lobes. The stiff nature of this part of the brain could therefore impact the readings of an MRE machine by reflecting or dampening the shear waves produced by an MRE device. One of the more common ways to replicate the effect of an MRE actuator is a device called an Impedance Tube (Almeida, 2013). Because MRE devices must be used in conjunction with an MRI machine, which is expensive, Impedance tubes can be used in order to test how waves affect a biological material. Impedance Tubes function by using sound waves to determine the relative stiffness of a material (Rao, 2014). The machine operates by creating a sound wave in the direction of an object, and then using microphones to determine what effect the material being tested had on the wave. This device will be used to test the effect that the Falx Cerebri has on waves that pass through and/or reflect off of it. The organic hard matter of the Falx Cerebri is not exposed to outside elements. To replicate this Falx Cerebri will need to be suspended in an artificially created soft tissue substitute. This substitute, known as a phantom, is a silicone gel substance that is extremely similar in both texture and density to brain matter (Keerthivasan, 2012) The ultimate purpose of these trials is to determine the effect of the Falx Cerebri upon MRE readings.
Project Description:
The goal of this project will be to determine the effect of the Falx Cerebri on the measurements of an MRE device. The first stages of this research will be to determine the effectiveness and usability of certain materials, specifically, the use of silicone phantoms. These phantoms will be necessary in order to further investigate the main goal of the research. The main part of these stages will be preparing and testing types of phantoms (which simulate brain tissue) in relation to induced shear waves. These phantoms can be created mixing gel products that are ordered online with different densities and volumes in order to accurately reproduce the effects of brain tissue in different situations. Ultimately, the phantoms will be used in the final stages of the research to stabilize the Falx Cerebri that are being tested and prevent movement during testing, as well as simulating the effects of the softer brain matter surrounding the Falx Cerebri. This process will be necessary in order to reduce variances during testing, as well as This stage of the research will not take long, likely 2 weeks or less, and will likely only be a precursor to the use of an Impedance tube. The testing of the Falx Cerebri in relation to MRE measurements will be conducted with the use of an Impedance Tube because are neither expensive nor hard to procure, contrary to an MRE device. The Impedance Tube generates and directs sound waves, which measures the stiffness of an object. This is accomplished by sending sound waves at specified frequencies at an object, then using microphones to detect the strength of the reflection of the waves, as well as the strength of the waves that pass through the object. This process mirrors that of an MRE device closely, which is why it was chosen to test this method. The Falx Cerebri will be tested at different angles in order to determine whether wave angle has an effect on the reading of an MRE device (which uses shear waves that are similar to the sound waves generated by the Impedance Tube). The reason behind testing the effect that rotation has upon the readings collected by a wave-propagating device, is that MRE devices can be situated at different angles in order to obtain a more accurate reading, and that depending on the angle, some orientations can be more effective from a medical standpoint than others. The readings gathered from this machine will be expressed in the form of frequencies, which will then be plugged into an equation to measure the stiffness of the object tested, as well as the magnitude to which the Falx Cerebri affected the waves produced by the Impedance tube.
Research Strategy:
The first part of this project will be to obtain organic samples of the Falx Cerebri (likely to be bovine) for testing. The next step will then be to properly orient the Falx Cerebri within a phantom solution, which will be purchased from one of a variety of companies that produce such a product, such as Factor II Inc.. Once the materials are obtained, the aim will be to test different densities and sizes of phantoms, as well the shape and orientation. Once it is determined what size and density of the phantoms will most accurately model brain tissue, it will be critical to stabilize and orient the organic samples for testing with the impedance tube or other secondary mechanical actuation devices such as piezoceramic and piezoelectric actuators. This stabilizing device will also be hold the phantoms in place when testing what effect the angular rotation of the Falx Cerebri has on MRE readings. Another major part of the project will be to build an Impedance tube, or to borrow one from another laboratory. A series of trials, using the Impedance Tube, will be conducted to determine the effect the Falx Cerebri has on the readings of a wave-propagating device dependending upon what frequency and wavelength at which the device is producing waves of force. These experiments will be conducted with the Falx Cerebri oriented at different angular rotations in order to see if the angle at which the propagated wave interacts with the Falx Cerebri at all effects the reliability of the reading. Finally, the readings gained from the Impedance tube will be plugged into an equation in order to test the total effect of the Falx Cerebri on the waves. The equation will help to determine if the orientation of the Falx Cerebri had an effect upon its perceived stiffness (effect) in relation to soft brain matter.
Bibliography:
Almeida, A. B., Jr. (2013). Design and Construction of a Low Cost Impedance Tube for Sound Absorption Coefficients Measurements. International Congress of Mechanical Engineering. Retrieved February 1, 2018. Glaser, K. J., Ehman, R. L., & Mariappan, Y. K. (2010). Elastography.
Encyclopedia of Magnetic Resonance. doi:10.1002/9780470034590.emrstm0148.pub2 Hiscox, L. V., Johnson, C. L., Barnhill, E., Mcgarry, M. D., Huston, J., Beek, E. J., . . . Roberts, N. (2016). Magnetic resonance elastography (MRE) of the human brain: technique, findings and clinical applications. Physics in Medicine and Biology,61(24). doi:10.1088/0031-9155/61/24/r401 Keerthivasan, M.B. (2012).
DEVELOPMENT OF A LOW COST IMPEDANCE TUBE TO MEASURE ACOUSTIC ABSORPTION AND TRANSMISSION LOSS OF MATERIALS. ASSE Annual Conference andExposition. Retrieved February 1, 2018. Uffmann, K., Abicht, C., Grote, W., Quick, H. H., & Ladd, M. E. (2002).
Design of an MR-compatible piezoelectric actuator for MR elastography. Concepts in Magnetic Resonance,15(4), 239-254. doi:10.1002/cmr.10045.
Longitudinal Driver Based Magnetic Resonance Elastography. University of Arizona. Retrieved February 11, 2018. Mariappan, Y. K., Glaser, K. J., & Ehman, R. L. (2010). Magnetic Resonance Elastography: A Review. Clinical Anatomy. doi:doi:10.1002/ca.21006. Rao, M. D., Dr. (2014).
The brain is one of the most important and delicate organs of the human anatomical system. It is these characteristics that lead scientists to devise newer and improved ways of detecting and fixing problems within the brain. The downsides with traditional methods of detecting anomalies within the human body is that when they are applied to the brain, they can have an extremely detrimental effects. Techniques such as X-Ray and PET, and MRI, which use radiation and magnetism respectively, are unpredictable when it come to the brain and have a chance of severely damaging cognitive functions. This proposed project will seek to determine the effect of specific parts of the brain upon specific proven non-invasive techniques used in the detection of brain tumors and other irregularities. There is limited research in this specific field, and thus this work will be important in determining the applicability of certain methods. This project will test the effect that the Falx Cerebri has on Magnetic Resonance Elastography actuator measurements, as well as the effect angular orientation has on the readings taken by this device. The overarching goal is determine the effects that certain conditions have on the effectiveness of Magnetic Resonance Elastography actuators in detecting brain tumors and other harmful anomalies.
Background:
Magnetic Resonance Elastography (MRE) is a non-invasive method for quantifying the mechanical properties of tissue in the brain (Mariappan et al., 2010). It functions by vibrating upon the surface of the head, creating shear waves which harmlessly pass through brain tissue, then taking magnetic resonance images of said shear waves using an MRI machine and analysing them to detect any potential anomalies in the brain (Uffman, 2002). It is an extremely promising technique which can be used to detect anomalies in brain tissue earlier rather than later (Hiscox, 2016). However, different structures within the brain can affect the way that these waves move. One of these structures, the Falx Cerebri, is a curved plate of hard dura matter(one of the substances that helps protect the brain) that runs through the center of the brain, separating the left and right lobes. The stiff nature of this part of the brain could therefore impact the readings of an MRE machine by reflecting or dampening the shear waves produced by an MRE device. One of the more common ways to replicate the effect of an MRE actuator is a device called an Impedance Tube (Almeida, 2013). Because MRE devices must be used in conjunction with an MRI machine, which is expensive, Impedance tubes can be used in order to test how waves affect a biological material. Impedance Tubes function by using sound waves to determine the relative stiffness of a material (Rao, 2014). The machine operates by creating a sound wave in the direction of an object, and then using microphones to determine what effect the material being tested had on the wave. This device will be used to test the effect that the Falx Cerebri has on waves that pass through and/or reflect off of it. The organic hard matter of the Falx Cerebri is not exposed to outside elements. To replicate this Falx Cerebri will need to be suspended in an artificially created soft tissue substitute. This substitute, known as a phantom, is a silicone gel substance that is extremely similar in both texture and density to brain matter (Keerthivasan, 2012) The ultimate purpose of these trials is to determine the effect of the Falx Cerebri upon MRE readings.
Project Description:
The goal of this project will be to determine the effect of the Falx Cerebri on the measurements of an MRE device. The first stages of this research will be to determine the effectiveness and usability of certain materials, specifically, the use of silicone phantoms. These phantoms will be necessary in order to further investigate the main goal of the research. The main part of these stages will be preparing and testing types of phantoms (which simulate brain tissue) in relation to induced shear waves. These phantoms can be created mixing gel products that are ordered online with different densities and volumes in order to accurately reproduce the effects of brain tissue in different situations. Ultimately, the phantoms will be used in the final stages of the research to stabilize the Falx Cerebri that are being tested and prevent movement during testing, as well as simulating the effects of the softer brain matter surrounding the Falx Cerebri. This process will be necessary in order to reduce variances during testing, as well as This stage of the research will not take long, likely 2 weeks or less, and will likely only be a precursor to the use of an Impedance tube. The testing of the Falx Cerebri in relation to MRE measurements will be conducted with the use of an Impedance Tube because are neither expensive nor hard to procure, contrary to an MRE device. The Impedance Tube generates and directs sound waves, which measures the stiffness of an object. This is accomplished by sending sound waves at specified frequencies at an object, then using microphones to detect the strength of the reflection of the waves, as well as the strength of the waves that pass through the object. This process mirrors that of an MRE device closely, which is why it was chosen to test this method. The Falx Cerebri will be tested at different angles in order to determine whether wave angle has an effect on the reading of an MRE device (which uses shear waves that are similar to the sound waves generated by the Impedance Tube). The reason behind testing the effect that rotation has upon the readings collected by a wave-propagating device, is that MRE devices can be situated at different angles in order to obtain a more accurate reading, and that depending on the angle, some orientations can be more effective from a medical standpoint than others. The readings gathered from this machine will be expressed in the form of frequencies, which will then be plugged into an equation to measure the stiffness of the object tested, as well as the magnitude to which the Falx Cerebri affected the waves produced by the Impedance tube.
Research Strategy:
The first part of this project will be to obtain organic samples of the Falx Cerebri (likely to be bovine) for testing. The next step will then be to properly orient the Falx Cerebri within a phantom solution, which will be purchased from one of a variety of companies that produce such a product, such as Factor II Inc.. Once the materials are obtained, the aim will be to test different densities and sizes of phantoms, as well the shape and orientation. Once it is determined what size and density of the phantoms will most accurately model brain tissue, it will be critical to stabilize and orient the organic samples for testing with the impedance tube or other secondary mechanical actuation devices such as piezoceramic and piezoelectric actuators. This stabilizing device will also be hold the phantoms in place when testing what effect the angular rotation of the Falx Cerebri has on MRE readings. Another major part of the project will be to build an Impedance tube, or to borrow one from another laboratory. A series of trials, using the Impedance Tube, will be conducted to determine the effect the Falx Cerebri has on the readings of a wave-propagating device dependending upon what frequency and wavelength at which the device is producing waves of force. These experiments will be conducted with the Falx Cerebri oriented at different angular rotations in order to see if the angle at which the propagated wave interacts with the Falx Cerebri at all effects the reliability of the reading. Finally, the readings gained from the Impedance tube will be plugged into an equation in order to test the total effect of the Falx Cerebri on the waves. The equation will help to determine if the orientation of the Falx Cerebri had an effect upon its perceived stiffness (effect) in relation to soft brain matter.
Bibliography:
Almeida, A. B., Jr. (2013). Design and Construction of a Low Cost Impedance Tube for Sound Absorption Coefficients Measurements. International Congress of Mechanical Engineering. Retrieved February 1, 2018. Glaser, K. J., Ehman, R. L., & Mariappan, Y. K. (2010). Elastography.
Encyclopedia of Magnetic Resonance. doi:10.1002/9780470034590.emrstm0148.pub2 Hiscox, L. V., Johnson, C. L., Barnhill, E., Mcgarry, M. D., Huston, J., Beek, E. J., . . . Roberts, N. (2016). Magnetic resonance elastography (MRE) of the human brain: technique, findings and clinical applications. Physics in Medicine and Biology,61(24). doi:10.1088/0031-9155/61/24/r401 Keerthivasan, M.B. (2012).
DEVELOPMENT OF A LOW COST IMPEDANCE TUBE TO MEASURE ACOUSTIC ABSORPTION AND TRANSMISSION LOSS OF MATERIALS. ASSE Annual Conference andExposition. Retrieved February 1, 2018. Uffmann, K., Abicht, C., Grote, W., Quick, H. H., & Ladd, M. E. (2002).
Design of an MR-compatible piezoelectric actuator for MR elastography. Concepts in Magnetic Resonance,15(4), 239-254. doi:10.1002/cmr.10045.
Longitudinal Driver Based Magnetic Resonance Elastography. University of Arizona. Retrieved February 11, 2018. Mariappan, Y. K., Glaser, K. J., & Ehman, R. L. (2010). Magnetic Resonance Elastography: A Review. Clinical Anatomy. doi:doi:10.1002/ca.21006. Rao, M. D., Dr. (2014).
