Pub Date : 2024-11-26DOI: 10.1109/OJUFFC.2024.3506532
Amirhossein Omidvar;Robert N. Rohling;Edmond Cretu;Mark E. Cresswell;Antony J. Hodgson
Conformal ultrasound imaging using large-area transducer arrays is an emerging technology with significant potential for real-time, continuous, functional, and health monitoring applications. This study addresses the challenge of fabricating such transducer arrays by presenting the development and preliminary imaging performance of a monolithic flexible capacitive micromachined ultrasonic transducer (CMUT) array—the longest reported to date. A 128-element, 91 mm long flexible array was designed and fabricated using a lithography process, with SU-8 CMUT structures on a bendable polyimide substrate. The array was then packaged by mounting it onto a flexible printed circuit board and coated with a thin polydimethylsiloxane (PDMS) layer for in vivo testing. Electrical impedance measurements confirmed the full functionality of all transducer elements, with an average center resonant frequency of 5.84 MHz (SD: 0.14 MHz). Pulse-echo imaging experiments demonstrated the array’s capability to detect specular reflections and resolve fine features under various curvatures. In vivo scans revealed outlines of a finger and superficial tissues in the forearm. Despite the limitations associated with the lack of custom front-end electronics and low signal-to-noise ratio beamforming strategies, this work demonstrates the feasibility of manufacturing a flexible CMUT array suitable for large-area conformal sonography.
{"title":"Preliminary Demonstration of Pulse-Echo Imaging With a Long Monolithic Flexible CMUT Array","authors":"Amirhossein Omidvar;Robert N. Rohling;Edmond Cretu;Mark E. Cresswell;Antony J. Hodgson","doi":"10.1109/OJUFFC.2024.3506532","DOIUrl":"https://doi.org/10.1109/OJUFFC.2024.3506532","url":null,"abstract":"Conformal ultrasound imaging using large-area transducer arrays is an emerging technology with significant potential for real-time, continuous, functional, and health monitoring applications. This study addresses the challenge of fabricating such transducer arrays by presenting the development and preliminary imaging performance of a monolithic flexible capacitive micromachined ultrasonic transducer (CMUT) array—the longest reported to date. A 128-element, 91 mm long flexible array was designed and fabricated using a lithography process, with SU-8 CMUT structures on a bendable polyimide substrate. The array was then packaged by mounting it onto a flexible printed circuit board and coated with a thin polydimethylsiloxane (PDMS) layer for in vivo testing. Electrical impedance measurements confirmed the full functionality of all transducer elements, with an average center resonant frequency of 5.84 MHz (SD: 0.14 MHz). Pulse-echo imaging experiments demonstrated the array’s capability to detect specular reflections and resolve fine features under various curvatures. In vivo scans revealed outlines of a finger and superficial tissues in the forearm. Despite the limitations associated with the lack of custom front-end electronics and low signal-to-noise ratio beamforming strategies, this work demonstrates the feasibility of manufacturing a flexible CMUT array suitable for large-area conformal sonography.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"4 ","pages":"191-203"},"PeriodicalIF":0.0,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10767731","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142798049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-08DOI: 10.1109/OJUFFC.2024.3494693
Mohammad Mohajery;Sebastien Salles;Torvald Espeland;Morten Smedsrud Wigen;Solveig Fadnes;Lasse Lovstakken
The velocity of mechanical waves (MW) in the heart reflects myocardial tissue properties. Different wave velocity estimation methods have been proposed, using the slope of the wave projection in M-mode, or based on the gradient of the time-of-flight (TOF) map (gradient method). In this work, we compare these methods using a simulation and 3D wave propagation in vivo. Waves were detected using both clutter filter wave imaging (CFWI) and tissue Doppler imaging (TDI). The effect of pipeline parameters on velocity estimation was studied. Finally, an in vivo investigation was made for healthy controls and patients with aortic stenosis. When the wave propagation was mainly in-plane, all methods yielded similar results, verified using both simulations and in vivo data. However, velocity overestimation occurred due to misalignment between the M-line and the wave propagation direction, and for wave-view misalignment when using the 2D gradient method. The gradient method was sensitive to processing parameters, where smoothing of the TOF map also led to an overestimation of the wave velocities. For our data, CFWI provided the most robust results, however, the choice of filter cutoff influenced the output, which became similar to TDI for high cutoff velocities. Our study shows that the gradient method can provide similar results as the M-mode slope when the wave propagation is aligned in-plane, and further provide localized wave velocity estimates in 2D and 3D, limited by smoothing requirements. This can be advantageous for mapping heterogeneous tissue properties, and the method can provide valuable clinical insight in the future.
心脏中机械波(MW)的速度反映了心肌组织的特性。目前已提出了不同的波速估算方法,有的使用 M 型中波投影的斜率,有的则基于飞行时间(TOF)图的梯度(梯度法)。在这项工作中,我们利用模拟和体内三维波传播对这些方法进行了比较。我们使用杂波滤波成像(CFWI)和组织多普勒成像(TDI)对波进行了检测。研究了管道参数对速度估计的影响。最后,对健康对照组和主动脉瓣狭窄患者进行了体内调查。当波主要在平面内传播时,所有方法都得出了相似的结果,并通过模拟和活体数据进行了验证。然而,在使用二维梯度法时,由于 M 线与波传播方向的错位以及波视角的错位,会出现速度高估的情况。梯度法对处理参数很敏感,TOF 图的平滑化也会导致波速的高估。对于我们的数据,CFWI 提供了最稳健的结果,然而,滤波器截止点的选择影响了输出结果,在截止点速度较高时,输出结果与 TDI 相似。我们的研究表明,当波在平面内传播时,梯度法可以提供与 M 模式斜率相似的结果,并进一步提供二维和三维的局部波速估计,但受平滑要求的限制。这对于绘制异质组织特性图非常有利,而且该方法在未来能为临床提供有价值的见解。
{"title":"The 3D Estimation of Mechanical Wave Velocities in the Heart: Methods and Insights","authors":"Mohammad Mohajery;Sebastien Salles;Torvald Espeland;Morten Smedsrud Wigen;Solveig Fadnes;Lasse Lovstakken","doi":"10.1109/OJUFFC.2024.3494693","DOIUrl":"https://doi.org/10.1109/OJUFFC.2024.3494693","url":null,"abstract":"The velocity of mechanical waves (MW) in the heart reflects myocardial tissue properties. Different wave velocity estimation methods have been proposed, using the slope of the wave projection in M-mode, or based on the gradient of the time-of-flight (TOF) map (gradient method). In this work, we compare these methods using a simulation and 3D wave propagation in vivo. Waves were detected using both clutter filter wave imaging (CFWI) and tissue Doppler imaging (TDI). The effect of pipeline parameters on velocity estimation was studied. Finally, an in vivo investigation was made for healthy controls and patients with aortic stenosis. When the wave propagation was mainly in-plane, all methods yielded similar results, verified using both simulations and in vivo data. However, velocity overestimation occurred due to misalignment between the M-line and the wave propagation direction, and for wave-view misalignment when using the 2D gradient method. The gradient method was sensitive to processing parameters, where smoothing of the TOF map also led to an overestimation of the wave velocities. For our data, CFWI provided the most robust results, however, the choice of filter cutoff influenced the output, which became similar to TDI for high cutoff velocities. Our study shows that the gradient method can provide similar results as the M-mode slope when the wave propagation is aligned in-plane, and further provide localized wave velocity estimates in 2D and 3D, limited by smoothing requirements. This can be advantageous for mapping heterogeneous tissue properties, and the method can provide valuable clinical insight in the future.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"4 ","pages":"177-190"},"PeriodicalIF":0.0,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10747501","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142679298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1109/OJUFFC.2024.3487147
Marco Pomponio;Archita Hati;Craig Nelson
In this paper, we present a direct digital measurement system capable of simultaneously measuring phase noise, amplitude noise, and Allan deviation with and without cross-correlation. The residual phase noise of the single-channel system achieves $mathscr {L}left ({{1 text {Hz}}}right)~ textrm {=} -143 text {dBc/Hz}$