Pub Date : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925899
Sergio Jiménez-Gambín, N. Jiménez, J. Benlloch, F. Camarena
Focused ultrasound is currently used in many emerging therapeutic applications for the non-invasive treatment of neurological disorders and pathologies inside the central nervous system. However, the accurate focusing of ultrasound beams at the central nervous system is mainly limited due to the strong phase aberrations produced by refraction and attenuation of the skull. We present 3D-printed acoustic holographic lenses for the generation of ultrasonic fields of complex spatial distribution inside the skull. Using holographic lenses with an aperture of 50 mm and working frequency of 1.1 MHz, we experimentally, numerically and theoretically produce acoustic beams whose spatial distribution match target structures of the central nervous system. In particular, we present three configurations of increasing complexity: a set of points, a curved trajectory and an arbitrary volume. Results show that, using low-cost 3D-printed lenses, ultrasonic beams can be focused not only at a single point, but overlapping at one or various target structures simultaneously, e.g., left and right hippocampi. These results open new paths to spread emerging therapeutic ultrasound applications including blood-brain barrier opening or neuromodulation using low-cost systems.
{"title":"Acoustic Holograms Allow the Generation of Complex Fields Inside the Central Nervous System","authors":"Sergio Jiménez-Gambín, N. Jiménez, J. Benlloch, F. Camarena","doi":"10.1109/ULTSYM.2019.8925899","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925899","url":null,"abstract":"Focused ultrasound is currently used in many emerging therapeutic applications for the non-invasive treatment of neurological disorders and pathologies inside the central nervous system. However, the accurate focusing of ultrasound beams at the central nervous system is mainly limited due to the strong phase aberrations produced by refraction and attenuation of the skull. We present 3D-printed acoustic holographic lenses for the generation of ultrasonic fields of complex spatial distribution inside the skull. Using holographic lenses with an aperture of 50 mm and working frequency of 1.1 MHz, we experimentally, numerically and theoretically produce acoustic beams whose spatial distribution match target structures of the central nervous system. In particular, we present three configurations of increasing complexity: a set of points, a curved trajectory and an arbitrary volume. Results show that, using low-cost 3D-printed lenses, ultrasonic beams can be focused not only at a single point, but overlapping at one or various target structures simultaneously, e.g., left and right hippocampi. These results open new paths to spread emerging therapeutic ultrasound applications including blood-brain barrier opening or neuromodulation using low-cost systems.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"19 1","pages":"2432-2434"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73658188","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 : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925890
Rehman Ali, J. Dahl
Our previous work on estimating the local speed of sound from average sound speed assumes a perfectly layered medium where sound speed is only allowed to vary axially away from the transducer surface. This layered-medium approach relies on inverting the relationship between the local interval sound speeds in each layer and the effective average sound speed up to a particular imaging depth. The primary limitation of this approach is that local sound speed estimation can become inaccurate in the presence of lateral variations in sound speed or a curved transducer surface. To better estimate sound speed in the presence of these non-idealities, we propose a travel-time tomographic approach that accounts for propagation paths from the scattering volume to each transducer element.
{"title":"Travel-Time Tomography for Local Sound Speed Reconstruction Using Average Sound Speeds","authors":"Rehman Ali, J. Dahl","doi":"10.1109/ULTSYM.2019.8925890","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925890","url":null,"abstract":"Our previous work on estimating the local speed of sound from average sound speed assumes a perfectly layered medium where sound speed is only allowed to vary axially away from the transducer surface. This layered-medium approach relies on inverting the relationship between the local interval sound speeds in each layer and the effective average sound speed up to a particular imaging depth. The primary limitation of this approach is that local sound speed estimation can become inaccurate in the presence of lateral variations in sound speed or a curved transducer surface. To better estimate sound speed in the presence of these non-idealities, we propose a travel-time tomographic approach that accounts for propagation paths from the scattering volume to each transducer element.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"5 1","pages":"2007-2010"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75606668","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 : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925898
Bowen Jing, Milton E Brown, Michael E. Davis, B. Lindsey
Nanoscale phase change contrast agents (PCCA) have been demonstrated for extravascular imaging in tissue. However, contrast in PCCA images is typically limited by physiological motion and incomplete cancelation of unwanted tissue signal. In this work, we develop an ultrafast inter-frame activation imaging sequence for high contrast PCCA imaging in the presence of physiological motion by imaging the inter-frame variation produced by activation of PCCA, which is distinguishable from tissue and blood motion. Phantom studies indicate that in the absence of tissue motion, the CTR of UIAU images is 19.55±0.42 dB while the CTR of the amplitude modulate + pulse inversion (AMPI) is 8.15±0.65 dB and the CTR of differential imaging is 24.20±1.22 dB. Furthermore, the CTR of these UIAU images can reach 51.43±3.3 dB by applying a denoising approach. With 20 mm/s motion, the CTR of UIAU and denoised UIAU images were 18.70±1.40 dB and 31.77±9.76 dB respectively, which were both significantly higher than that of amplitude modulation + pulse inversion (AMPI) and differential images. The preliminary in vivo imaging results indicate the UIAU could significantly suppress the background tissue in the presence of physiological motion.
{"title":"High contrast imaging of low boiling point phase change contrast agents in moving tissue with ultrafast inter-frame activation imaging sequence","authors":"Bowen Jing, Milton E Brown, Michael E. Davis, B. Lindsey","doi":"10.1109/ULTSYM.2019.8925898","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925898","url":null,"abstract":"Nanoscale phase change contrast agents (PCCA) have been demonstrated for extravascular imaging in tissue. However, contrast in PCCA images is typically limited by physiological motion and incomplete cancelation of unwanted tissue signal. In this work, we develop an ultrafast inter-frame activation imaging sequence for high contrast PCCA imaging in the presence of physiological motion by imaging the inter-frame variation produced by activation of PCCA, which is distinguishable from tissue and blood motion. Phantom studies indicate that in the absence of tissue motion, the CTR of UIAU images is 19.55±0.42 dB while the CTR of the amplitude modulate + pulse inversion (AMPI) is 8.15±0.65 dB and the CTR of differential imaging is 24.20±1.22 dB. Furthermore, the CTR of these UIAU images can reach 51.43±3.3 dB by applying a denoising approach. With 20 mm/s motion, the CTR of UIAU and denoised UIAU images were 18.70±1.40 dB and 31.77±9.76 dB respectively, which were both significantly higher than that of amplitude modulation + pulse inversion (AMPI) and differential images. The preliminary in vivo imaging results indicate the UIAU could significantly suppress the background tissue in the presence of physiological motion.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"18 1","pages":"135-138"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74598069","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 : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925665
Hong-Cin Liou, F. Sabba, G. Wells, O. Balogun
Biofilms are biological materials composed of microbial communities encased in a self-produced extracellular polymeric substance (EPS). The viscoelastic properties of biofilms are related to the cross-link density in the EPS and ultimately the cohesiveness of biofilms. Accurate measurement of biofilm viscoelastic properties at the mesoscale remains a challenge. Rheological measurements, although being more common, provide only global properties, do not permit in-situ characterization, and are not amenable to complex sample geometries. To address these challenges, our work seeks to develop a nondestructive framework for characterizing biofilm viscoelastic properties using elastic wave propagation measured by the optical coherence elastography technique. The framework holds great potential to elucidate spatially varying mechanical properties and their correlation with sample morphology and composition.
{"title":"Mechanical Characterization of Biofilms by Optical Coherence Elastography (OCE) Measurements of Elastic Waves","authors":"Hong-Cin Liou, F. Sabba, G. Wells, O. Balogun","doi":"10.1109/ULTSYM.2019.8925665","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925665","url":null,"abstract":"Biofilms are biological materials composed of microbial communities encased in a self-produced extracellular polymeric substance (EPS). The viscoelastic properties of biofilms are related to the cross-link density in the EPS and ultimately the cohesiveness of biofilms. Accurate measurement of biofilm viscoelastic properties at the mesoscale remains a challenge. Rheological measurements, although being more common, provide only global properties, do not permit in-situ characterization, and are not amenable to complex sample geometries. To address these challenges, our work seeks to develop a nondestructive framework for characterizing biofilm viscoelastic properties using elastic wave propagation measured by the optical coherence elastography technique. The framework holds great potential to elucidate spatially varying mechanical properties and their correlation with sample morphology and composition.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"1 1","pages":"832-835"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74724586","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 : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925783
O. Adelegan, Zachary A. Coutant, Xiao Zhang, F. Y. Yamaner, Ömer Oralkan
A two-dimensional (2D) transducer array is an integral part of a three-dimensional (3D) ultrasound imaging system as well as a compact ultrasound system for neurostimulation to steer and focus the beam in a volume. In this paper, a sacrificial etching-based fabrication process for implementing a 16x16-element 2D CMUT array on a glass substrate with through-glass-interconnects is described in detail. Across the fabricated 256 elements of the 2D CMUT array, the mean resonant frequency is measured as 4.76 MHz with a standard deviation of 46.6 kHz. The fabricated 2D CMUT array shows a 100% element yield in fabrication and excellent uniformity in device performance. The process offers the advantages of developing 2D CMUT arrays on glass substrates that do not need to be compatible with anodic bonding.
{"title":"A 2D Capacitive Micromachined Ultrasonic Transducer (CMUT) Array with Through-Glass-Via Interconnects Fabricated Using Sacrificial Etching Process","authors":"O. Adelegan, Zachary A. Coutant, Xiao Zhang, F. Y. Yamaner, Ömer Oralkan","doi":"10.1109/ULTSYM.2019.8925783","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925783","url":null,"abstract":"A two-dimensional (2D) transducer array is an integral part of a three-dimensional (3D) ultrasound imaging system as well as a compact ultrasound system for neurostimulation to steer and focus the beam in a volume. In this paper, a sacrificial etching-based fabrication process for implementing a 16x16-element 2D CMUT array on a glass substrate with through-glass-interconnects is described in detail. Across the fabricated 256 elements of the 2D CMUT array, the mean resonant frequency is measured as 4.76 MHz with a standard deviation of 46.6 kHz. The fabricated 2D CMUT array shows a 100% element yield in fabrication and excellent uniformity in device performance. The process offers the advantages of developing 2D CMUT arrays on glass substrates that do not need to be compatible with anodic bonding.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"215 1","pages":"1205-1208"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73944471","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 : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925644
Yu-Cheng Chang, Meng-Lin Li
Ultrasound speckle noise degrades imaging contrast and hides anatomical details; thus causing inaccuracy in clinical diagnosis. Although speckle reduction methods such as classical nonlocal means (NLM), optimized Bayesian nonlocal means (OBNLM), and speckle reducing anisotropic diffusion (SRAD) filters have been proposed for years, they still suffer two major problems – insufficient preservation of characteristic details such as calcifications and inordinate blurring making image appearance artificial. To solve the two problems, we propose a novel foveated nonlocal means despeckle filtering technique, inspired by the human visual system. Conventional NLM filters despeckle via searching for analogous patches at different areas within the image and then estimating the impulse response by the degrees of similarity appraised by a windowed Euler distance between the target and searching patches. In our technique, foveated self-similarity is used instead of conventional self-similarity. The foveated self-similarity is based on a new patch operator mimicking human retina properties, sharpening patch pixels in the center and blurring them near the periphery. Moreover, throughout the literature, the tuning of the search window and patch sizes and other parameters are not consistent; nonetheless, in this study, they are tuned universally from imaging perspective, i.e., according to the size of point spread function which allows the adaption to different imaging systems and settings. Simulations and clinical data (not shown here) were used to verify our proposed method. The performance of our proposed method is also compared with the classical despeckle filters. The results demonstrate that the proposed technique can remove speckles forcefully while more effectively retaining structural edge details, textures, and point-like structures. Quantitative measures such as contrast-to-noise ratio, edge preservation index and contrast measure are also presented.
{"title":"Foveated Nonlocal Means Despeckle Filtering for Ultrasound Imaging: Imaging Perspective","authors":"Yu-Cheng Chang, Meng-Lin Li","doi":"10.1109/ULTSYM.2019.8925644","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925644","url":null,"abstract":"Ultrasound speckle noise degrades imaging contrast and hides anatomical details; thus causing inaccuracy in clinical diagnosis. Although speckle reduction methods such as classical nonlocal means (NLM), optimized Bayesian nonlocal means (OBNLM), and speckle reducing anisotropic diffusion (SRAD) filters have been proposed for years, they still suffer two major problems – insufficient preservation of characteristic details such as calcifications and inordinate blurring making image appearance artificial. To solve the two problems, we propose a novel foveated nonlocal means despeckle filtering technique, inspired by the human visual system. Conventional NLM filters despeckle via searching for analogous patches at different areas within the image and then estimating the impulse response by the degrees of similarity appraised by a windowed Euler distance between the target and searching patches. In our technique, foveated self-similarity is used instead of conventional self-similarity. The foveated self-similarity is based on a new patch operator mimicking human retina properties, sharpening patch pixels in the center and blurring them near the periphery. Moreover, throughout the literature, the tuning of the search window and patch sizes and other parameters are not consistent; nonetheless, in this study, they are tuned universally from imaging perspective, i.e., according to the size of point spread function which allows the adaption to different imaging systems and settings. Simulations and clinical data (not shown here) were used to verify our proposed method. The performance of our proposed method is also compared with the classical despeckle filters. The results demonstrate that the proposed technique can remove speckles forcefully while more effectively retaining structural edge details, textures, and point-like structures. Quantitative measures such as contrast-to-noise ratio, edge preservation index and contrast measure are also presented.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"9 1","pages":"2064-2066"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74266777","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 : 2019-10-01DOI: 10.1109/ULTSYM.2019.8926081
P. Muralt, V. Pashchenko, F. Parsapour, S. Mertin, B. Heinz, P. Nicolay
The discovery of enhanced piezoelectricity in solid solutions of AlN and ScN is certainly one of the most important events in piezoelectric MEMS. As compared to pure AlN, it brought a crucial factor 2 to 3 improvement in a number of figures of merit governing the performance of MEMS devices. The aim of this contribution is to give a short overview on actual topics in processing, properties, and applications in RF filters and sensors.
{"title":"Growth, Properties, and Applications of Al1-xScxN Thin Films","authors":"P. Muralt, V. Pashchenko, F. Parsapour, S. Mertin, B. Heinz, P. Nicolay","doi":"10.1109/ULTSYM.2019.8926081","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8926081","url":null,"abstract":"The discovery of enhanced piezoelectricity in solid solutions of AlN and ScN is certainly one of the most important events in piezoelectric MEMS. As compared to pure AlN, it brought a crucial factor 2 to 3 improvement in a number of figures of merit governing the performance of MEMS devices. The aim of this contribution is to give a short overview on actual topics in processing, properties, and applications in RF filters and sensors.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"115 3-4","pages":"255-257"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72600568","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 : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925654
S. Fujii, T. Teraji, Takahiro Shimaoka, K. Ichikawa, S. Koizumi
We herein investigated surface acoustic wave (SAW) filters made of diamond and demonstrated that SAW resonators of 5 GHz band can be easily realized. Diamond has been previously studied for application in power devices and quantum computers. In particular, 12C diamond has been applied to quantum computers using nitrogen-vacancy (NV) centers. We fabricated a SAW resonator for 12C isotopically enriched diamond. Our resonator has a resonance frequency of 6 GHz and an anti-communicating frequency of 13 GHz. In the case of the Sezawa mode, the sound speed increased by 30%. We also found that the Young's modulus doubled with the removal of a small percentage of 13C. However, the reason for high coupling factor is yet to be discovered.
{"title":"One-port SAW resonator on diamond made of isotopically enriched 12C","authors":"S. Fujii, T. Teraji, Takahiro Shimaoka, K. Ichikawa, S. Koizumi","doi":"10.1109/ULTSYM.2019.8925654","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925654","url":null,"abstract":"We herein investigated surface acoustic wave (SAW) filters made of diamond and demonstrated that SAW resonators of 5 GHz band can be easily realized. Diamond has been previously studied for application in power devices and quantum computers. In particular, 12C diamond has been applied to quantum computers using nitrogen-vacancy (NV) centers. We fabricated a SAW resonator for 12C isotopically enriched diamond. Our resonator has a resonance frequency of 6 GHz and an anti-communicating frequency of 13 GHz. In the case of the Sezawa mode, the sound speed increased by 30%. We also found that the Young's modulus doubled with the removal of a small percentage of 13C. However, the reason for high coupling factor is yet to be discovered.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"36 1","pages":"739-741"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74575398","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 : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925757
Gabriela Torres, Tomasz J. Czernuszewicz, C. Gallippi
Atherosclerotic plaque rupture potential is conferred by plaque composition and structure. We have previously shown in humans in vivo that carotid plaque components can be automatically delineated by a support vector machine (SVM) classifier considering normalized crosscorrelation (NCC)-derived measures of ARFI-induced displacement. We now extend our prior work by hypothesizing that classification is improved by using displacements derived using blind source separation (BSS). In 20 carotid plaques imaged in vivo in patients undergoing carotid endarterectomy (CEA) were imaged prior to extraction, and specimens were harvested after CEA for histological processing. ARFI displacement profiles were calculated from each of the first five principal components of the RF data and used as inputs to the SVM classifier. The classifier was evaluated by 5-fold cross-validation, with the histological samples acting as gold standards. From the output SVM likelihood matrices, ROC curves were calculated for separating collagen from calcium and lipid-rich necrotic core from intraplaque hemorrhage. For all examined plaques, inputting displacement profiles derived from the first four eigenvectors to the SVM classifier increased sensitivity and specificity over using NCCderived displacement profiles. These results suggest that using BSS-derived displacement profiles as inputs to the SVM classifier improves discrimination of carotid plaque components that are correlated to vulnerability for rupture.
{"title":"Blind source separation-based tracking of ARFIinduced displacements for improved automatic delineation of carotid plaque components in humans, in vivo","authors":"Gabriela Torres, Tomasz J. Czernuszewicz, C. Gallippi","doi":"10.1109/ULTSYM.2019.8925757","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925757","url":null,"abstract":"Atherosclerotic plaque rupture potential is conferred by plaque composition and structure. We have previously shown in humans in vivo that carotid plaque components can be automatically delineated by a support vector machine (SVM) classifier considering normalized crosscorrelation (NCC)-derived measures of ARFI-induced displacement. We now extend our prior work by hypothesizing that classification is improved by using displacements derived using blind source separation (BSS). In 20 carotid plaques imaged in vivo in patients undergoing carotid endarterectomy (CEA) were imaged prior to extraction, and specimens were harvested after CEA for histological processing. ARFI displacement profiles were calculated from each of the first five principal components of the RF data and used as inputs to the SVM classifier. The classifier was evaluated by 5-fold cross-validation, with the histological samples acting as gold standards. From the output SVM likelihood matrices, ROC curves were calculated for separating collagen from calcium and lipid-rich necrotic core from intraplaque hemorrhage. For all examined plaques, inputting displacement profiles derived from the first four eigenvectors to the SVM classifier increased sensitivity and specificity over using NCCderived displacement profiles. These results suggest that using BSS-derived displacement profiles as inputs to the SVM classifier improves discrimination of carotid plaque components that are correlated to vulnerability for rupture.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"16 1","pages":"2217-2219"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78382472","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 : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925979
S. Ménigot, Nesrine Houhat, J. Girault
In non destructive testing, improvements have been made possible by taking into account the harmonic frequencies, as in agri-food domain. The transmitted signal are often selected empirically as a fixed-frequency Gaussian pulse, by taking into account the transducer bandwidth only. However, waveform should take into account all the features of the ultrasound system and of the medium. To design the waveform, a genetic algorithm looks for the best stochastic wave. However, one of limitations in this optimization process is the high amount of transmitted waves. To reduce this number, instead of transmitting wide band stochastic waves, narrow band stochastic waves limited by the transducer bandwidth are preferred. The optimization was thus applied on the detection of fat cluster in milk by maximizing the signal-to-noise ratio (SNR), while decreasing the amount of transmitted waves. Twelve combinations from different limited bandwidths of transmitted waves were tested. Whereas the low cut-off frequencies did not change the performances, the high cut-off frequencies affected the convergence speed. In this study, it is shown that the best optimization was twelve times faster with the high cut-off frequency of 5.6 MHz and led to a gain of 62% compared to the SNR obtained with a best fixed-frequency sine wave.
{"title":"Optimal Prefiltered Stochastic Transmitted Waves for Fat Inclusion Detection in Milk with Harmonic Ultrasound","authors":"S. Ménigot, Nesrine Houhat, J. Girault","doi":"10.1109/ULTSYM.2019.8925979","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925979","url":null,"abstract":"In non destructive testing, improvements have been made possible by taking into account the harmonic frequencies, as in agri-food domain. The transmitted signal are often selected empirically as a fixed-frequency Gaussian pulse, by taking into account the transducer bandwidth only. However, waveform should take into account all the features of the ultrasound system and of the medium. To design the waveform, a genetic algorithm looks for the best stochastic wave. However, one of limitations in this optimization process is the high amount of transmitted waves. To reduce this number, instead of transmitting wide band stochastic waves, narrow band stochastic waves limited by the transducer bandwidth are preferred. The optimization was thus applied on the detection of fat cluster in milk by maximizing the signal-to-noise ratio (SNR), while decreasing the amount of transmitted waves. Twelve combinations from different limited bandwidths of transmitted waves were tested. Whereas the low cut-off frequencies did not change the performances, the high cut-off frequencies affected the convergence speed. In this study, it is shown that the best optimization was twelve times faster with the high cut-off frequency of 5.6 MHz and led to a gain of 62% compared to the SNR obtained with a best fixed-frequency sine wave.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"342 1","pages":"631-634"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75940378","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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