Pub Date : 2014-10-23DOI: 10.1109/ULTSYM.2014.0016
Keith Johnston, P. Prentice, B. Gerold
Cavitation mediated effects in liquids exposed to ultrasound, play pivotal roles in a number of industrial arenas, including precision acoustic cleaning (megasonics) and sonochemistry. The spontaneous occurrence of cavitation, and the subsequent interaction with the liquid and the acoustic field, is however poorly understood, which prevents optimization for any given application. In this paper we report on observations made of single isolated cavitation-bubble clouds, exposed to a well characterized burst of propagating focused ultrasound, and the resulting translational motion of the clouds under the action of the primary acoustic radiation force. As may be expected, larger clouds develop under higher intensity insonations, which translate away from the ultrasound source more rapidly, although a larger associated drag force somewhat tempers the effect. Critically, however, a resonant condition is identified whereby small clouds at lower intensities translate much more rapidly than might otherwise be expected. A model is derived from first principles, adapted to the experimental conditions and demonstrates good agreement with the observations, including the frequency resonance. We anticipate the results will have significance for any application in which understanding and predicting a dynamic cavitating liquid is important, particularly under non-standing wave conditions.
{"title":"Cavitation cloud translation in focused ultrasound","authors":"Keith Johnston, P. Prentice, B. Gerold","doi":"10.1109/ULTSYM.2014.0016","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0016","url":null,"abstract":"Cavitation mediated effects in liquids exposed to ultrasound, play pivotal roles in a number of industrial arenas, including precision acoustic cleaning (megasonics) and sonochemistry. The spontaneous occurrence of cavitation, and the subsequent interaction with the liquid and the acoustic field, is however poorly understood, which prevents optimization for any given application. In this paper we report on observations made of single isolated cavitation-bubble clouds, exposed to a well characterized burst of propagating focused ultrasound, and the resulting translational motion of the clouds under the action of the primary acoustic radiation force. As may be expected, larger clouds develop under higher intensity insonations, which translate away from the ultrasound source more rapidly, although a larger associated drag force somewhat tempers the effect. Critically, however, a resonant condition is identified whereby small clouds at lower intensities translate much more rapidly than might otherwise be expected. A model is derived from first principles, adapted to the experimental conditions and demonstrates good agreement with the observations, including the frequency resonance. We anticipate the results will have significance for any application in which understanding and predicting a dynamic cavitating liquid is important, particularly under non-standing wave conditions.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122661514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-10-23DOI: 10.1109/ULTSYM.2014.0328
A. Hosokawa
Numerical analysis of ultrasound backscattering in cancellous bone was performed by using three-dimensional finite-difference time-domain (FDTD) simulations with numerical models reconstructed from microcomputed tomographic images of bovine bone. In the simulations, two cancellous bone models with different thicknesses were used. In each model, an artificial absorbing boundary was set at the back surface opposite to the front surface toward which an ultrasound pulse wave was transmitted from a concave transmitter/receiver in water. From the difference between the simulated waveforms for the two bone models, the reflected wave from the front surface could be canceled, and only the backscattered waves inside the bone could be extracted. For the ultrasound transmission parallel to the main orientation of the trabecular network, the backscattered waves from various bone depths were analyzed. The peak-to-peak amplitudes of the backscattered waves from the deep bone depths were moderately correlated with porosity [R2 = 0.43-0.54 (P <; 0.001)]. The backscattered waves from the deeper bone depth could be more clearly separated into the fast and slow waves, and the backscattered wave amplitude could be regarded as the slow wave amplitude.
{"title":"Finite-difference time-domain analysis of ultrasound backscattering in cancellous bone","authors":"A. Hosokawa","doi":"10.1109/ULTSYM.2014.0328","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0328","url":null,"abstract":"Numerical analysis of ultrasound backscattering in cancellous bone was performed by using three-dimensional finite-difference time-domain (FDTD) simulations with numerical models reconstructed from microcomputed tomographic images of bovine bone. In the simulations, two cancellous bone models with different thicknesses were used. In each model, an artificial absorbing boundary was set at the back surface opposite to the front surface toward which an ultrasound pulse wave was transmitted from a concave transmitter/receiver in water. From the difference between the simulated waveforms for the two bone models, the reflected wave from the front surface could be canceled, and only the backscattered waves inside the bone could be extracted. For the ultrasound transmission parallel to the main orientation of the trabecular network, the backscattered waves from various bone depths were analyzed. The peak-to-peak amplitudes of the backscattered waves from the deep bone depths were moderately correlated with porosity [R2 = 0.43-0.54 (P <; 0.001)]. The backscattered waves from the deeper bone depth could be more clearly separated into the fast and slow waves, and the backscattered wave amplitude could be regarded as the slow wave amplitude.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123001515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-10-23DOI: 10.1109/ULTSYM.2014.0235
Hongmin Ahn, Min Sung, K. Been, W. Moon
Photoacoustic imaging (PAI) is a non-invasive medical imaging technique that has been studied by many research groups. It surpasses the penetration-depth limits of optical imaging and is able to provide functional imaging for tumor-vascular interactions and hemoglobin oxygenation mapping. The imaging quality is dominated by the transducer performance; thus, the transducer plays an important role. In this study, we examined a piezoelectric micromachined ultrasound transducer (pMUT) array with 10 MHz resonant frequency for PAI systems. pMUTs can be used with array or endoscopic probes due to their small size by bulk micromachining process. Additionally, their receiving sensitivity and power efficiency are higher than those of general thickness-mode piezoelectric transducers.
{"title":"Piezoelectric micromachined ultrasound array transducer with 31 channels for photoacoustic imaging","authors":"Hongmin Ahn, Min Sung, K. Been, W. Moon","doi":"10.1109/ULTSYM.2014.0235","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0235","url":null,"abstract":"Photoacoustic imaging (PAI) is a non-invasive medical imaging technique that has been studied by many research groups. It surpasses the penetration-depth limits of optical imaging and is able to provide functional imaging for tumor-vascular interactions and hemoglobin oxygenation mapping. The imaging quality is dominated by the transducer performance; thus, the transducer plays an important role. In this study, we examined a piezoelectric micromachined ultrasound transducer (pMUT) array with 10 MHz resonant frequency for PAI systems. pMUTs can be used with array or endoscopic probes due to their small size by bulk micromachining process. Additionally, their receiving sensitivity and power efficiency are higher than those of general thickness-mode piezoelectric transducers.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123016560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-10-23DOI: 10.1109/ULTSYM.2014.0379
Hasan Yetik, A. Ergun, A. Bozkurt
In CMUT based ultrasound catheter ablation systems, transducer arrays and their drivers are to be kept as small as possible due to size restrictions, while maintaining a reasonable number of channels for proper beamforming. In addition, these systems should be highly integrated with minimal power consumption for flexibility and functionality. Despite the size restrictions on these systems, such problems can be overcome by ASICs. In this work, we present a simple 8 channel high-frequency, high-voltage driver, together with its beamforming and control circuitry designed with AMS's H35 high voltage process.
{"title":"An integrated beamforming driver for CMUT based ultrasound catheter ablation system","authors":"Hasan Yetik, A. Ergun, A. Bozkurt","doi":"10.1109/ULTSYM.2014.0379","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0379","url":null,"abstract":"In CMUT based ultrasound catheter ablation systems, transducer arrays and their drivers are to be kept as small as possible due to size restrictions, while maintaining a reasonable number of channels for proper beamforming. In addition, these systems should be highly integrated with minimal power consumption for flexibility and functionality. Despite the size restrictions on these systems, such problems can be overcome by ASICs. In this work, we present a simple 8 channel high-frequency, high-voltage driver, together with its beamforming and control circuitry designed with AMS's H35 high voltage process.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122139954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-10-23DOI: 10.1109/ULTSYM.2014.0130
T. Mateo, Y. Mofid, J. Grégoire, F. Ossant
In ophthalmic ultrasonography the crystalline lens is known to be the main source of phase aberration, as ultrasounds (US) propagate about 10% faster than in the surrounding intraocular medium. Consequently, it causes significant decrease in both spatial and contrast resolution together with distortion effects on axial B-scans. An eye-adapted beamforming (BF) has been developed and experimented with a 20 MHz linear array working with a custom US research scanner, the ECODERM. The eye-adapted BF computes focusing delays that compensate for crystalline phase aberration, including refraction effects, by assuming the intraocular medium consists of two homogeneous media (crystalline lens + aqueous and vitreous humors). The proposed BF was tested in vitro by imaging a wire phantom through an eye phantom consisting of a synthetic gelatin lens anatomically set up in an appropriate liquid (turpentine) to approach the in vivo velocity ratio. The synthetic lens shape corresponded to that of an adult human crystalline lens in unaccommodated state. Both image quality and fidelity from the adapted BF were assessed, in relation to that in homogeneous medium and compared with conventional delay-and-sum BF over the aberrating medium. Finally, first ex vivo experimentation on human eyes are presented. In vitro quantitative study showed 2-fold improvement of the lateral resolution, greater sensitivity and 90% reduction of the spatial error (from 758 μm to 76 μm) with adapted BF compared to conventional BF. Compared to optimal results in homogeneous medium (pure turpentine), lateral resolution was only 39% lower with adapted BF. First ex vivo results showed a higher detailed view of the posterior coat and a global restoration of the spatial fidelity promising for biometry and especially phakometry.
{"title":"An adapted beamforming free from crystalline lens phase aberration for ocular ultrasonography - In vitro and Ex vivo results with a 20 MHz linear array","authors":"T. Mateo, Y. Mofid, J. Grégoire, F. Ossant","doi":"10.1109/ULTSYM.2014.0130","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0130","url":null,"abstract":"In ophthalmic ultrasonography the crystalline lens is known to be the main source of phase aberration, as ultrasounds (US) propagate about 10% faster than in the surrounding intraocular medium. Consequently, it causes significant decrease in both spatial and contrast resolution together with distortion effects on axial B-scans. An eye-adapted beamforming (BF) has been developed and experimented with a 20 MHz linear array working with a custom US research scanner, the ECODERM. The eye-adapted BF computes focusing delays that compensate for crystalline phase aberration, including refraction effects, by assuming the intraocular medium consists of two homogeneous media (crystalline lens + aqueous and vitreous humors). The proposed BF was tested in vitro by imaging a wire phantom through an eye phantom consisting of a synthetic gelatin lens anatomically set up in an appropriate liquid (turpentine) to approach the in vivo velocity ratio. The synthetic lens shape corresponded to that of an adult human crystalline lens in unaccommodated state. Both image quality and fidelity from the adapted BF were assessed, in relation to that in homogeneous medium and compared with conventional delay-and-sum BF over the aberrating medium. Finally, first ex vivo experimentation on human eyes are presented. In vitro quantitative study showed 2-fold improvement of the lateral resolution, greater sensitivity and 90% reduction of the spatial error (from 758 μm to 76 μm) with adapted BF compared to conventional BF. Compared to optimal results in homogeneous medium (pure turpentine), lateral resolution was only 39% lower with adapted BF. First ex vivo results showed a higher detailed view of the posterior coat and a global restoration of the spatial fidelity promising for biometry and especially phakometry.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117044323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-10-23DOI: 10.1109/ULTSYM.2014.0146
Donghwan Kim, M. Kuntzman, N. Hall
We present an unconventional capacitive micromachined ultrasonic transducer in which a vacuum-sealed cavity beneath a diaphragm layer is comprised of an internal beam that pivots and has a first rocking or rotational vibration mode and a second flapping mode of vibration. It is anticipated that the unique structure may find application in biologically-inspired ultrasound sensors that simultaneously detect omnidirectional sound pressure and pressure gradient. Vacuum sealing the cavity in which the pivoting beam resides eliminates squeeze-film damping that would otherwise cause excessive damping and/or stiffness. This paper presents scanning electron micrographs of successfully fabricated and sealed prototypes and dynamic frequency response measurements, which reveal a fundamental rocking mode of vibration at 480 kHz.
{"title":"Microfabrication of a capacitive micromachined ultrasonic transducer (CMUT) with an internally sealed pivot","authors":"Donghwan Kim, M. Kuntzman, N. Hall","doi":"10.1109/ULTSYM.2014.0146","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0146","url":null,"abstract":"We present an unconventional capacitive micromachined ultrasonic transducer in which a vacuum-sealed cavity beneath a diaphragm layer is comprised of an internal beam that pivots and has a first rocking or rotational vibration mode and a second flapping mode of vibration. It is anticipated that the unique structure may find application in biologically-inspired ultrasound sensors that simultaneously detect omnidirectional sound pressure and pressure gradient. Vacuum sealing the cavity in which the pivoting beam resides eliminates squeeze-film damping that would otherwise cause excessive damping and/or stiffness. This paper presents scanning electron micrographs of successfully fabricated and sealed prototypes and dynamic frequency response measurements, which reveal a fundamental rocking mode of vibration at 480 kHz.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117250983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-10-23DOI: 10.1109/ULTSYM.2014.0055
Thu-Mai Nguyen, Shaozhen Song, Lei Shi, Ruikang K. Wang, M. O’Donnell, Tueng T. Shen, Zhihong Huang
Assessing the biomechanical properties of the cornea can provide clinically valuable information in addition to structural images for better management of pathologies (e.g. glaucoma) or refractive surgeries. OCT provides a micron scale and high sensitivity that are ideal for ophthalmic applications. We propose a shear wave elastography (SWE) method for the cornea based on phase-sensitive optical coherence tomography (PhS-OCT). SWE consists in launching a propagating shear wave in tissues and retrieving tissue elasticity from the shear wave speed. We used a piezo-electric actuator in contact with the cornea to induce shear waves that were then tracked using a PhSOCT system operating in M-B mode at an equivalent frame rate of 45 kHz. The actuator was driven by a broadband, linear-swept frequency sine. The corresponding displacements were numerically transformed into a short and spatially localized pulse by a pulse compression algorithm. The local shear wave speed was then computed using time-of-flight estimations. We performed experiments on excised human corneas obtained from the eye bank. The corneas were mounted on an artificial anterior chamber in which the IOP could be varied. Elasticity measurements were acquired for IOP ranging from 10 to 40 mmHg. These preliminary studies demonstrate the feasibility of using PhS-OCT for elastography of human corneas. Further studies will aim at developing non-contact shear sources for clinical translation.
{"title":"Shear wave elastography of ex vivo human corneas using phase-sensitive optical coherence tomography","authors":"Thu-Mai Nguyen, Shaozhen Song, Lei Shi, Ruikang K. Wang, M. O’Donnell, Tueng T. Shen, Zhihong Huang","doi":"10.1109/ULTSYM.2014.0055","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0055","url":null,"abstract":"Assessing the biomechanical properties of the cornea can provide clinically valuable information in addition to structural images for better management of pathologies (e.g. glaucoma) or refractive surgeries. OCT provides a micron scale and high sensitivity that are ideal for ophthalmic applications. We propose a shear wave elastography (SWE) method for the cornea based on phase-sensitive optical coherence tomography (PhS-OCT). SWE consists in launching a propagating shear wave in tissues and retrieving tissue elasticity from the shear wave speed. We used a piezo-electric actuator in contact with the cornea to induce shear waves that were then tracked using a PhSOCT system operating in M-B mode at an equivalent frame rate of 45 kHz. The actuator was driven by a broadband, linear-swept frequency sine. The corresponding displacements were numerically transformed into a short and spatially localized pulse by a pulse compression algorithm. The local shear wave speed was then computed using time-of-flight estimations. We performed experiments on excised human corneas obtained from the eye bank. The corneas were mounted on an artificial anterior chamber in which the IOP could be varied. Elasticity measurements were acquired for IOP ranging from 10 to 40 mmHg. These preliminary studies demonstrate the feasibility of using PhS-OCT for elastography of human corneas. Further studies will aim at developing non-contact shear sources for clinical translation.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"2013 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128217643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-10-23DOI: 10.1109/ULTSYM.2014.0232
J. Tsujino, E. Sugimoto
Ultrasonic complex vibration welding was applied for deep and narrow area of electronic parts positioned at long distance from the vibration system. Usually, electric resistance welding was used to weld such part, but there are possible defect caused by sparked metal particles radiated from welding position. To overcome the defect and make possible to join such deep area, 20 kHz and 27 kHz ultrasonic complex vibration systems using 2.0- and 3.0-mm-diameter, 70- to 100-mm-long hard metal and tungsten welding tips were developed. Using the ultrasonic complex vibration systems, various metal specimens including copper, nickel clad copper terminal and steel or nickel coated steel cases were successfully welded with weld strength almost equal to these material strength.
{"title":"Ultrasonic welding of electronic parts and devices using a long and thin complex vibration welding tip","authors":"J. Tsujino, E. Sugimoto","doi":"10.1109/ULTSYM.2014.0232","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0232","url":null,"abstract":"Ultrasonic complex vibration welding was applied for deep and narrow area of electronic parts positioned at long distance from the vibration system. Usually, electric resistance welding was used to weld such part, but there are possible defect caused by sparked metal particles radiated from welding position. To overcome the defect and make possible to join such deep area, 20 kHz and 27 kHz ultrasonic complex vibration systems using 2.0- and 3.0-mm-diameter, 70- to 100-mm-long hard metal and tungsten welding tips were developed. Using the ultrasonic complex vibration systems, various metal specimens including copper, nickel clad copper terminal and steel or nickel coated steel cases were successfully welded with weld strength almost equal to these material strength.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128224475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-10-23DOI: 10.1109/ULTSYM.2014.0212
Deqing Kong, M. Kurosawa
To study the efficiency of the substrate in a surface acoustic wave motor, a novel interdigital transducer reflector will be designed in this research. Then, to evaluate the performance of the novel stator, the stator is fabricated with the aid of the basic semiconductor planar process. At last, some measurements, including the recycle efficiency and vibration amplitude, are introduced.
{"title":"Evaluation of a novel reflector in a surface acoustic wave motor","authors":"Deqing Kong, M. Kurosawa","doi":"10.1109/ULTSYM.2014.0212","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0212","url":null,"abstract":"To study the efficiency of the substrate in a surface acoustic wave motor, a novel interdigital transducer reflector will be designed in this research. Then, to evaluate the performance of the novel stator, the stator is fabricated with the aid of the basic semiconductor planar process. At last, some measurements, including the recycle efficiency and vibration amplitude, are introduced.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124566132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-10-23DOI: 10.1109/ULTSYM.2014.0305
Sheronica L. James, M. Howell, Qi Wang, Gregory T. Clement
Chiari Type I Malformation is a condition in which the cerebellar tonsils, small lobes on the undersurface of each half of the cerebellum, protrude through the base of the skull and press against the spinal cord. Assessing the motion of these herniated structures and their effects on cerebrospinal fluid dynamics is of significant clinical interest, particularly since the condition has been implicated in the formation of serious secondary disorders affecting the brain and spinal cord, such as hydrocephalus and syringomyelia. While MRI studies have shown no statistically significant differences in tonsillar motion of Chiari Type I patients compared to healthy individuals, surgeons have reported rapid tonsil motion as observed by intraoperative sonography during decompression surgery. However, it remains unclear whether this discrepancy is due to limitations of the MRI technique or decompression facilitating increased movement. Therefore, we aim to test the hypothesis that localized movement of cerebellar tonsils can be assessed non-invasively in the intact skull using ultrasound. Here, an investigation into the use of a novel methodology for transkull imaging in assessing cerebellar tonsil motion is presented. Two transducers (1MHz, 0.5 inches in diameter) were placed rostrocaudally on the frontal and suboccipital surfaces of a water-filled ex vivo human skull. A sinusoidal pulse was transmitted into the specimen from one transducer, and recorded by the receiving transducer at the opposite surface. Starting at the edge of the foramen magnum, the transducers were rotated at 8mm intervals in a counterclockwise direction. A tissue phantom was also used to mimic the cerebellar tonsils. Attenuation through the skull and motion detection in the tissue phantom was analyzed. It is shown that at a transducer frequency of 1MHz, our through transmission ultrasonic technique allows for a substantial energy transmission of up 8.6%. No signal was observed at the same points in reflection mode. To our knowledge, this level of energy transmission has been achievable only through a very limited temporal acoustic window, which fails in up to 29% of patients in a general population. Results demonstrate the feasibility of using this type of transducer system for a non-invasive pre-surgical assessment of cerebellar tonsil motion without the need for an acoustic window.
{"title":"A transcranial device and method for detecting cerebellar brain motion","authors":"Sheronica L. James, M. Howell, Qi Wang, Gregory T. Clement","doi":"10.1109/ULTSYM.2014.0305","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0305","url":null,"abstract":"Chiari Type I Malformation is a condition in which the cerebellar tonsils, small lobes on the undersurface of each half of the cerebellum, protrude through the base of the skull and press against the spinal cord. Assessing the motion of these herniated structures and their effects on cerebrospinal fluid dynamics is of significant clinical interest, particularly since the condition has been implicated in the formation of serious secondary disorders affecting the brain and spinal cord, such as hydrocephalus and syringomyelia. While MRI studies have shown no statistically significant differences in tonsillar motion of Chiari Type I patients compared to healthy individuals, surgeons have reported rapid tonsil motion as observed by intraoperative sonography during decompression surgery. However, it remains unclear whether this discrepancy is due to limitations of the MRI technique or decompression facilitating increased movement. Therefore, we aim to test the hypothesis that localized movement of cerebellar tonsils can be assessed non-invasively in the intact skull using ultrasound. Here, an investigation into the use of a novel methodology for transkull imaging in assessing cerebellar tonsil motion is presented. Two transducers (1MHz, 0.5 inches in diameter) were placed rostrocaudally on the frontal and suboccipital surfaces of a water-filled ex vivo human skull. A sinusoidal pulse was transmitted into the specimen from one transducer, and recorded by the receiving transducer at the opposite surface. Starting at the edge of the foramen magnum, the transducers were rotated at 8mm intervals in a counterclockwise direction. A tissue phantom was also used to mimic the cerebellar tonsils. Attenuation through the skull and motion detection in the tissue phantom was analyzed. It is shown that at a transducer frequency of 1MHz, our through transmission ultrasonic technique allows for a substantial energy transmission of up 8.6%. No signal was observed at the same points in reflection mode. To our knowledge, this level of energy transmission has been achievable only through a very limited temporal acoustic window, which fails in up to 29% of patients in a general population. Results demonstrate the feasibility of using this type of transducer system for a non-invasive pre-surgical assessment of cerebellar tonsil motion without the need for an acoustic window.","PeriodicalId":153901,"journal":{"name":"2014 IEEE International Ultrasonics Symposium","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124690755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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