Pub Date : 2025-08-08DOI: 10.1109/OJUFFC.2025.3596866
Archita Hati;Marco Pomponio;Nicholas V. Nardelli;Tanner Grogan;Kyungtae Kim;Dahyeon Lee;Jun Ye;Tara M. Fortier;Andrew Ludlow;Craig W. Nelson
This paper presents a frequency synthesis that achieves exceptional stability by transferring optical signals to the radio frequency (RF) domain at 100 MHz. We describe and characterize two synthesis chains composed of a cryogenic silicon cavity-stabilized laser at 1542 nm and an ultra-low expansion (ULE) glass cavity at 1157 nm, both converted to 10 GHz signals via Ti:Sapphire and Er/Yb:glass optical frequency combs (OFCs). The 10 GHz microwave outputs are further divided down to 100 MHz using a commercial microwave prescaler, which exhibits a residual frequency instability of $sigma _{y}({1}~text {s})lt {10}^{-{15}}$ and low 10-18 level at a few thousand seconds. Measurements are performed using a newly developed custom ultra-low-noise digital measurement system and are compared to the carrier-suppression technique. The new system enables high-sensitivity evaluation across the entire synthesis chain, from the optical and microwave heterodynes as well as the direct RF signals. Results show an absolute instability of ${sigma }_{y}({1}~text {s})~approx ~{4.7}times {10}^{-{16}}$ at 100 MHz. This represents the first demonstration of such low instability at 100 MHz, corresponding to a phase noise of −140 dBc/Hz at a 1 Hz offset and significantly surpassing earlier systems. These advancements open new opportunities for precision metrology and timing systems.
{"title":"Radio Frequency From Optical With Instabilities Below 10-15-Generation and Measurement","authors":"Archita Hati;Marco Pomponio;Nicholas V. Nardelli;Tanner Grogan;Kyungtae Kim;Dahyeon Lee;Jun Ye;Tara M. Fortier;Andrew Ludlow;Craig W. Nelson","doi":"10.1109/OJUFFC.2025.3596866","DOIUrl":"https://doi.org/10.1109/OJUFFC.2025.3596866","url":null,"abstract":"This paper presents a frequency synthesis that achieves exceptional stability by transferring optical signals to the radio frequency (RF) domain at 100 MHz. We describe and characterize two synthesis chains composed of a cryogenic silicon cavity-stabilized laser at 1542 nm and an ultra-low expansion (ULE) glass cavity at 1157 nm, both converted to 10 GHz signals via Ti:Sapphire and Er/Yb:glass optical frequency combs (OFCs). The 10 GHz microwave outputs are further divided down to 100 MHz using a commercial microwave prescaler, which exhibits a residual frequency instability of <inline-formula> <tex-math>$sigma _{y}({1}~text {s})lt {10}^{-{15}}$ </tex-math></inline-formula> and low 10-18 level at a few thousand seconds. Measurements are performed using a newly developed custom ultra-low-noise digital measurement system and are compared to the carrier-suppression technique. The new system enables high-sensitivity evaluation across the entire synthesis chain, from the optical and microwave heterodynes as well as the direct RF signals. Results show an absolute instability of <inline-formula> <tex-math>${sigma }_{y}({1}~text {s})~approx ~{4.7}times {10}^{-{16}}$ </tex-math></inline-formula> at 100 MHz. This represents the first demonstration of such low instability at 100 MHz, corresponding to a phase noise of −140 dBc/Hz at a 1 Hz offset and significantly surpassing earlier systems. These advancements open new opportunities for precision metrology and timing systems.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"5 ","pages":"127-134"},"PeriodicalIF":2.9,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11121396","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144880475","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 : 2025-08-05DOI: 10.1109/OJUFFC.2025.3596042
Vahid M. Safarzadeh;Konstantina Papangelopoulou;Marta Orlowska;Hans Dierckx;Jan D’Hooge
High Frame Rate Speckle Tracking Echocardiography (HFR-STE) offers a method to pinpoint the local onset of contraction in the left ventricle (LV) and generate mechanical activation maps. In this paper, a new patient-specific spatiotemporal approach is proposed to identify activation times on left ventricular strain rate (SR) curves automatically. Curves are collected from 2D HFR-STE according to the 16-segment model. Using a Locally Weighted Principal Component Analysis (LWPCA), the main pattern of each segment’s SR curve is extracted locally. The first positive-to-negative zero-crossing point on the first principal component is identified as the activation time. Validation with a dataset of 40 subjects (20 healthy volunteers and 20 patients) showed that 94% of estimated activation times closely matched the expert-identified times, differing by no more than 16ms. Quantitative and qualitative comparisons between LWPCA and (weighted) averaging are also reported. Also, the automatically generated activation maps closely resemble their manually created counterparts, demonstrating good visual similarity.
{"title":"Automated Measurement of Local Mechanical Activation on High Frame Rate Echocardiography","authors":"Vahid M. Safarzadeh;Konstantina Papangelopoulou;Marta Orlowska;Hans Dierckx;Jan D’Hooge","doi":"10.1109/OJUFFC.2025.3596042","DOIUrl":"https://doi.org/10.1109/OJUFFC.2025.3596042","url":null,"abstract":"High Frame Rate Speckle Tracking Echocardiography (HFR-STE) offers a method to pinpoint the local onset of contraction in the left ventricle (LV) and generate mechanical activation maps. In this paper, a new patient-specific spatiotemporal approach is proposed to identify activation times on left ventricular strain rate (SR) curves automatically. Curves are collected from 2D HFR-STE according to the 16-segment model. Using a Locally Weighted Principal Component Analysis (LWPCA), the main pattern of each segment’s SR curve is extracted locally. The first positive-to-negative zero-crossing point on the first principal component is identified as the activation time. Validation with a dataset of 40 subjects (20 healthy volunteers and 20 patients) showed that 94% of estimated activation times closely matched the expert-identified times, differing by no more than 16ms. Quantitative and qualitative comparisons between LWPCA and (weighted) averaging are also reported. Also, the automatically generated activation maps closely resemble their manually created counterparts, demonstrating good visual similarity.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"5 ","pages":"123-126"},"PeriodicalIF":2.9,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11113317","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144867646","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}
Evaluation of the backscatter coefficient (BSC) from soft tissues has many applications for medical diagnosis. However, electronic noise and spatial variations often affect BSC estimation, requiring spatial averaging inside a region of interest (ROI) that reduces spatial resolution compared to the B-mode images. This study explores 3D BSC estimation using a matrix probes to address this trade-off by allowing narrower ROIs without losing robustness. A comparison study between a 1024-element matrix probe (V8) and two linear probes (L12-5, L22-8) was made on homogeneous agar-based phantoms with Orgasol particles (5, 10, and $20~mu $ m). BSC was computed using the reference phantom method, and robustness was assessed via the BSC standard deviation across ROIs. Results showed that, despite the lower B-mode resolution and longer correlation length between A-lines, volumetric estimation with a matrix probe offered comparable accuracy while enhancing robustness and resolution in the BSC map compared to the standard 2D estimation. These results could be beneficial for the analysis of complex heterogeneous media.
软组织后向散射系数（BSC）的评估在医学诊断中有许多应用。然而，电子噪声和空间变化经常影响BSC估计，需要在感兴趣区域（ROI）内进行空间平均，与b模式图像相比，这降低了空间分辨率。本研究使用矩阵探针探索3D BSC估计，通过允许更窄的roi而不失去鲁棒性来解决这种权衡。采用1024元矩阵探针（V8）和线性探针（L12-5、L22-8）在含Orgasol粒子（5、10、20~ $ mu $ m）的均相琼脂模型上进行了对比研究。采用参考模体法计算平衡计分卡，并通过roi之间的平衡计分卡标准差评估鲁棒性。结果表明，尽管b模式分辨率较低，a线之间的相关长度较长，但与标准2D估计相比，矩阵探针的体积估计在增强BSC图的鲁棒性和分辨率的同时提供了相当的精度。这些结果可用于复杂非均质介质的分析。
{"title":"Volumetric Estimation of the Backscatter Coefficient With a Matrix Probe","authors":"Valentin Mazellier;François Varray;Pauline Muleki-Seya","doi":"10.1109/OJUFFC.2025.3588811","DOIUrl":"https://doi.org/10.1109/OJUFFC.2025.3588811","url":null,"abstract":"Evaluation of the backscatter coefficient (BSC) from soft tissues has many applications for medical diagnosis. However, electronic noise and spatial variations often affect BSC estimation, requiring spatial averaging inside a region of interest (ROI) that reduces spatial resolution compared to the B-mode images. This study explores 3D BSC estimation using a matrix probes to address this trade-off by allowing narrower ROIs without losing robustness. A comparison study between a 1024-element matrix probe (V8) and two linear probes (L12-5, L22-8) was made on homogeneous agar-based phantoms with Orgasol particles (5, 10, and <inline-formula> <tex-math>$20~mu $ </tex-math></inline-formula>m). BSC was computed using the reference phantom method, and robustness was assessed via the BSC standard deviation across ROIs. Results showed that, despite the lower B-mode resolution and longer correlation length between A-lines, volumetric estimation with a matrix probe offered comparable accuracy while enhancing robustness and resolution in the BSC map compared to the standard 2D estimation. These results could be beneficial for the analysis of complex heterogeneous media.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"5 ","pages":"119-122"},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11079648","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144680840","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 : 2025-06-06DOI: 10.1109/OJUFFC.2025.3577590
Sophie V. Heymans;Marcus Ingram;Bram Carlier;Brecht Vandenborre;Marc Fournelle;Alessandro Ramalli;François Rottenberg;Koen van den Abeele;Jan D'Hooge
Superheated nanodroplets (NDs) are proposed for in vivo radiation dose sensing applications, based on their ability to vaporize into echogenic microbubbles when exposed to ionizing radiation. Combined with Ultrasound Localization Microscopy (ULM), the ultrafast detection of radiation-induced ND vaporization produces super-resolved vaporization maps that match the radiation field with sub-millimeter accuracy. However, in the presence of flow, discriminating between microbubbles moving in the field of view and radiation-induced vaporization events is not trivial. As an alternative, sparse acoustic signatures emitted by vaporizing NDs can be super-localized by passive ULM, i.e. P-ULM. In this work, we extend our previous 2D implementation of P-ULM to 3D, using a large aperture matrix array probe. We exposed perfluorobutane NDs to a proton beam and recorded their vaporization signatures during irradiation. The events were extracted from the radiofrequency channel data using a spatiotemporal filtering approach and super-localized by fitting the time differences of arrival between channels to a one-way time of flight model. The vaporization maps were overlaid on the proton beam distribution and estimated the proton range and beam dispersion within $0.98~pm ~0.04$ mm and $0.03~pm ~0.02$ mm of the reference range measurement (depth-dose distribution in water measured with a diode), respectively. These results pave the way for volumetric dose mapping using radiosensitive nanodroplets and passive imaging.
{"title":"Volumetric Passive Ultrasound Localization Microscopy of Radiation-Induced Nanodroplet Vaporization With a Large Aperture Matrix Array","authors":"Sophie V. Heymans;Marcus Ingram;Bram Carlier;Brecht Vandenborre;Marc Fournelle;Alessandro Ramalli;François Rottenberg;Koen van den Abeele;Jan D'Hooge","doi":"10.1109/OJUFFC.2025.3577590","DOIUrl":"https://doi.org/10.1109/OJUFFC.2025.3577590","url":null,"abstract":"Superheated nanodroplets (NDs) are proposed for in vivo radiation dose sensing applications, based on their ability to vaporize into echogenic microbubbles when exposed to ionizing radiation. Combined with Ultrasound Localization Microscopy (ULM), the ultrafast detection of radiation-induced ND vaporization produces super-resolved vaporization maps that match the radiation field with sub-millimeter accuracy. However, in the presence of flow, discriminating between microbubbles moving in the field of view and radiation-induced vaporization events is not trivial. As an alternative, sparse acoustic signatures emitted by vaporizing NDs can be super-localized by passive ULM, i.e. P-ULM. In this work, we extend our previous 2D implementation of P-ULM to 3D, using a large aperture matrix array probe. We exposed perfluorobutane NDs to a proton beam and recorded their vaporization signatures during irradiation. The events were extracted from the radiofrequency channel data using a spatiotemporal filtering approach and super-localized by fitting the time differences of arrival between channels to a one-way time of flight model. The vaporization maps were overlaid on the proton beam distribution and estimated the proton range and beam dispersion within <inline-formula> <tex-math>$0.98~pm ~0.04$ </tex-math></inline-formula> mm and <inline-formula> <tex-math>$0.03~pm ~0.02$ </tex-math></inline-formula> mm of the reference range measurement (depth-dose distribution in water measured with a diode), respectively. These results pave the way for volumetric dose mapping using radiosensitive nanodroplets and passive imaging.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"5 ","pages":"108-113"},"PeriodicalIF":0.0,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11027146","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144281284","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}
Cardiac shear wave elastography (SWE) is a non-invasive technique to assess myocardial stiffness, based on the speed of waves that travel through the heart after valve closure. The wave physics underlying natural SWE remains incompletely understood. Therefore, we investigated the impact of wave excitation sources on 3 wave propagation aspects – wave amplitude (determined as wave acceleration magnitude), temporal wave width and speed. SWE was applied to 17 patients with aortic stenosis (AS), 13 AS patients that underwent transcatheter aortic valve implantation (TAVI), 10 AS patients that underwent surgical aortic valve replacement (AVR) and 18 age-matched healthy volunteers (HV). Absolute wave acceleration was lower in AS, TAVI and AVR patients compared to HV (1.5±0.60 vs 2.8±1.1 m/s2; p=0.001; 1.6±0.78 vs 2.8±1.1 m/s2; p=0.010; 1.7±0.66 vs 2.8±1.1 m/s2; p=0.015). Wave acceleration amplitude (measured as negative peak acceleration of the tissue) correlated with wave speed (r=0.388; p=0.003), implying that absolute wave acceleration is smaller in a stiffer heart. Subgroup analysis showed that the correlation between wave peak acceleration and speed is less steep in AS patients vs. HV (slopes: 0.23 vs 0.47 s). This implies that stenotic valves generate a wave with a lower acceleration magnitude compared to native valves. Further, temporal wave width was lower in TAVI patients vs. HV (8.7±2.3 vs 12.5±3.0 ms; p=0.002) and there was no difference in wave speed after aortic valve closure (AVC) between the groups. To conclude, wave acceleration magnitude and width offer additional insights into SWE physics next to wave speed and should be verified in a larger cohort.
心脏剪切波弹性成像（SWE）是一种评估心肌硬度的无创技术，基于瓣膜关闭后穿过心脏的波的速度。自然SWE背后的波动物理仍未完全被理解。因此，我们研究了波激励源对波传播3个方面的影响——波幅（以波加速度大小确定）、时间波宽度和速度。SWE应用于17例主动脉瓣狭窄患者（AS）， 13例经导管主动脉瓣植入术（TAVI）的AS患者，10例手术主动脉瓣置换术（AVR）的AS患者和18例年龄匹配的健康志愿者（HV）。AS、TAVI和AVR患者的绝对波加速度较HV患者低(1.5±0.60 vs 2.8±1.1 m/s2；p = 0.001;1.6±0.78 vs 2.8±1.1 m/s2；p = 0.010;1.7±0.66 vs 2.8±1.1 m/s2；p = 0.015)。波加速度幅值（以组织负峰值加速度测量）与波速相关(r=0.388；P =0.003)，这意味着在较硬的心脏中，绝对波加速度较小。亚组分析显示，AS患者与HV患者相比，波峰加速度和速度之间的相关性不那么陡峭（斜率：0.23 vs 0.47 s）。这意味着狭窄瓣膜产生的波与原生瓣膜相比具有较低的加速度量级。此外，TAVI患者的颞波宽度低于HV患者（8.7±2.3 vs 12.5±3.0 ms）；p=0.002)，两组间主动脉瓣关闭（AVC）后的波速无差异。综上所述，波加速度的大小和宽度除了波速之外，还提供了对SWE物理的进一步了解，应该在更大的队列中进行验证。
{"title":"The Impact of Valve Stenosis and Replacement on Wave Characteristics in Cardiac Shear Wave Elastography","authors":"Laurine Wouters;Lennert Minten;Marta Orlowska;Annette Caenen;Jürgen Duchenne;Jens-Uwe Voigt;Jan D’Hooge","doi":"10.1109/OJUFFC.2025.3577142","DOIUrl":"https://doi.org/10.1109/OJUFFC.2025.3577142","url":null,"abstract":"Cardiac shear wave elastography (SWE) is a non-invasive technique to assess myocardial stiffness, based on the speed of waves that travel through the heart after valve closure. The wave physics underlying natural SWE remains incompletely understood. Therefore, we investigated the impact of wave excitation sources on 3 wave propagation aspects – wave amplitude (determined as wave acceleration magnitude), temporal wave width and speed. SWE was applied to 17 patients with aortic stenosis (AS), 13 AS patients that underwent transcatheter aortic valve implantation (TAVI), 10 AS patients that underwent surgical aortic valve replacement (AVR) and 18 age-matched healthy volunteers (HV). Absolute wave acceleration was lower in AS, TAVI and AVR patients compared to HV (1.5±0.60 vs 2.8±1.1 m/s2; p=0.001; 1.6±0.78 vs 2.8±1.1 m/s2; p=0.010; 1.7±0.66 vs 2.8±1.1 m/s2; p=0.015). Wave acceleration amplitude (measured as negative peak acceleration of the tissue) correlated with wave speed (r=0.388; p=0.003), implying that absolute wave acceleration is smaller in a stiffer heart. Subgroup analysis showed that the correlation between wave peak acceleration and speed is less steep in AS patients vs. HV (slopes: 0.23 vs 0.47 s). This implies that stenotic valves generate a wave with a lower acceleration magnitude compared to native valves. Further, temporal wave width was lower in TAVI patients vs. HV (8.7±2.3 vs 12.5±3.0 ms; p=0.002) and there was no difference in wave speed after aortic valve closure (AVC) between the groups. To conclude, wave acceleration magnitude and width offer additional insights into SWE physics next to wave speed and should be verified in a larger cohort.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"5 ","pages":"114-118"},"PeriodicalIF":0.0,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11027079","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144492373","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 : 2025-06-05DOI: 10.1109/OJUFFC.2025.3541756
{"title":"IEEE OPEN JOURNAL OF ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL","authors":"","doi":"10.1109/OJUFFC.2025.3541756","DOIUrl":"https://doi.org/10.1109/OJUFFC.2025.3541756","url":null,"abstract":"","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"5 ","pages":"C2-C2"},"PeriodicalIF":0.0,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11026032","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144219708","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 : 2025-06-04DOI: 10.1109/OJUFFC.2025.3576722
Håvard Kjellmo Arnestad;Andreas Austeng;Sven Peter Näsholm
A wide variety of transmit sequences can be employed in medical ultrasound, including plane waves, diverging waves, and focused beams. The choice of sequence often involves trade-offs between resolution, signal-to-noise ratio (SNR), frame rate, and harmonic imaging capabilities. However, the desirable mathematical property of orthogonality (i.e., absence of cross-talk) between transmits has generally received less attention. This property, often lacking, becomes particularly relevant for the recent REFoCUS (retrospective encoding for conventional ultrasound sequences) technique, which we in this work connect to the array signal processing technique called beamspace processing. Given an arbitrary transmit sequence, REFoCUS enables the recovery of signals from single-element transmissions (known as the multistatic dataset) thereby enhancing beamforming flexibility. In this context, the choice of transmit sequence influences the recovery process when using the intuitively appealing and computationally efficient adjoint-based method, which must be replaced by a regularized pseudoinverse for general applicability. In the current work, we derive the “closest” alternative to any chosen transmit sequence that makes the regularized and adjoint methods yield equal estimates of the multistatic dataset, and show via numerical experiments a reduction in beam and/or element cross-talk. The derivation is based on a matrix nearness problem of finding the nearest orthogonal (or unitary) matrix to the encoding matrix using singular value decomposition (SVD). The resulting transmit sequences offer a time-domain equivalent understanding of the regularized REFoCUS method, as well as a solution for optimizing the invertibility of ultrasound sequences.
{"title":"Construction of Orthogonal Transmit Sequences Using the Nearest Orthogonal Matrix","authors":"Håvard Kjellmo Arnestad;Andreas Austeng;Sven Peter Näsholm","doi":"10.1109/OJUFFC.2025.3576722","DOIUrl":"https://doi.org/10.1109/OJUFFC.2025.3576722","url":null,"abstract":"A wide variety of transmit sequences can be employed in medical ultrasound, including plane waves, diverging waves, and focused beams. The choice of sequence often involves trade-offs between resolution, signal-to-noise ratio (SNR), frame rate, and harmonic imaging capabilities. However, the desirable mathematical property of orthogonality (i.e., absence of cross-talk) between transmits has generally received less attention. This property, often lacking, becomes particularly relevant for the recent REFoCUS (retrospective encoding for conventional ultrasound sequences) technique, which we in this work connect to the array signal processing technique called beamspace processing. Given an arbitrary transmit sequence, REFoCUS enables the recovery of signals from single-element transmissions (known as the multistatic dataset) thereby enhancing beamforming flexibility. In this context, the choice of transmit sequence influences the recovery process when using the intuitively appealing and computationally efficient adjoint-based method, which must be replaced by a regularized pseudoinverse for general applicability. In the current work, we derive the “closest” alternative to any chosen transmit sequence that makes the regularized and adjoint methods yield equal estimates of the multistatic dataset, and show via numerical experiments a reduction in beam and/or element cross-talk. The derivation is based on a matrix nearness problem of finding the nearest orthogonal (or unitary) matrix to the encoding matrix using singular value decomposition (SVD). The resulting transmit sequences offer a time-domain equivalent understanding of the regularized REFoCUS method, as well as a solution for optimizing the invertibility of ultrasound sequences.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"5 ","pages":"103-107"},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11023854","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144264239","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 : 2025-04-30DOI: 10.1109/OJUFFC.2025.3566006
Hasti Rostamikhanghahi;Marcus Ingram;Brian G. Booth;Jan D’Hooge
Percutaneous Scaphoid Fixation is a minimally invasive technique used to treat fractures of the scaphoid, the most fractured bone in the wrist. A significant challenge in this procedure is managing complications due to scaphoid movement due to wrist motion. This study aims to enhance the effectiveness of the intervention by introducing a novel wearable ultrasound array capable of flexible adherence and real-time tracking. By accurately monitoring scaphoid movement throughout the surgery, this innovation seeks to improve the overall success of the treatment. In previous research, a wearable transducer was designed to track the scaphoid during Percutaneous Scaphoid Fixation. In this study, ultrasound data was collected from this transducer and streamed to MATLAB, where an in-house developed algorithm employed template matching methods to track the scaphoid, specifically by identifying image segments that match a predefined template. With this method, we were able to demonstrate online processing at a frame rate of 28 Hz, which aligns with most clinical scanners, indicating the potential of this scaphoid tracking method for deployment on a clinical scanner.
{"title":"Online Scaphoid Tracking Using a Wearable and Flexible Ultrasound Array: A First Proof of Concept","authors":"Hasti Rostamikhanghahi;Marcus Ingram;Brian G. Booth;Jan D’Hooge","doi":"10.1109/OJUFFC.2025.3566006","DOIUrl":"https://doi.org/10.1109/OJUFFC.2025.3566006","url":null,"abstract":"Percutaneous Scaphoid Fixation is a minimally invasive technique used to treat fractures of the scaphoid, the most fractured bone in the wrist. A significant challenge in this procedure is managing complications due to scaphoid movement due to wrist motion. This study aims to enhance the effectiveness of the intervention by introducing a novel wearable ultrasound array capable of flexible adherence and real-time tracking. By accurately monitoring scaphoid movement throughout the surgery, this innovation seeks to improve the overall success of the treatment. In previous research, a wearable transducer was designed to track the scaphoid during Percutaneous Scaphoid Fixation. In this study, ultrasound data was collected from this transducer and streamed to MATLAB, where an in-house developed algorithm employed template matching methods to track the scaphoid, specifically by identifying image segments that match a predefined template. With this method, we were able to demonstrate online processing at a frame rate of 28 Hz, which aligns with most clinical scanners, indicating the potential of this scaphoid tracking method for deployment on a clinical scanner.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"5 ","pages":"58-61"},"PeriodicalIF":0.0,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10981429","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144073254","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 : 2025-04-15DOI: 10.1109/OJUFFC.2025.3560938
Hasti Rostamikhanghahi;Marcus Ingram;Brian G. Booth;Jan D’Hooge
Scaphoid fractures, the most common of wrist bone fractures, are typically treated using Percutaneous Scaphoid Fixation (PSF). Incorporating ultrasound guidance into this technique could reduce reliance on fluoroscopy, thereby avoiding ionizing radiation and improving procedural accuracy. However, the scaphoid’s position can shift as a result of hand movement during PSF, adding complexity to the procedure. Real-time ultrasound motion tracking of the scaphoid during PSF could simplify the intervention, which would necessitate a flexible transducer array to maintain contact during wrist motion. Our previous research proposed a transducer design with two parallel flexible 1D arrays, enabling simultaneous acquisition of two parallel images. This study focuses on transitioning from theoretical design to practical application by evaluating the performance of the custom array in terms of image quality using phantoms. We assessed image quality using the generalized contrast-to-noise ratio (gCNR) on a cyst phantom and the full width at half maximum (FWHM) on a wire phantom. Results demonstrated gCNR values above 0.67 and FWHM values below 0.70 mm across all sequences. These measurements fall within the acceptable range for the phantoms. Since the primary goal of the array is to track the scaphoid bone during surgery, requiring relatively high image quality, the values observed in this study are suitable for this application.
{"title":"Evaluation of a Dual Linear Flexible Ultrasound Array for Surgical Interventional Guidance","authors":"Hasti Rostamikhanghahi;Marcus Ingram;Brian G. Booth;Jan D’Hooge","doi":"10.1109/OJUFFC.2025.3560938","DOIUrl":"https://doi.org/10.1109/OJUFFC.2025.3560938","url":null,"abstract":"Scaphoid fractures, the most common of wrist bone fractures, are typically treated using Percutaneous Scaphoid Fixation (PSF). Incorporating ultrasound guidance into this technique could reduce reliance on fluoroscopy, thereby avoiding ionizing radiation and improving procedural accuracy. However, the scaphoid’s position can shift as a result of hand movement during PSF, adding complexity to the procedure. Real-time ultrasound motion tracking of the scaphoid during PSF could simplify the intervention, which would necessitate a flexible transducer array to maintain contact during wrist motion. Our previous research proposed a transducer design with two parallel flexible 1D arrays, enabling simultaneous acquisition of two parallel images. This study focuses on transitioning from theoretical design to practical application by evaluating the performance of the custom array in terms of image quality using phantoms. We assessed image quality using the generalized contrast-to-noise ratio (gCNR) on a cyst phantom and the full width at half maximum (FWHM) on a wire phantom. Results demonstrated gCNR values above 0.67 and FWHM values below 0.70 mm across all sequences. These measurements fall within the acceptable range for the phantoms. Since the primary goal of the array is to track the scaphoid bone during surgery, requiring relatively high image quality, the values observed in this study are suitable for this application.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"5 ","pages":"43-47"},"PeriodicalIF":0.0,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10965791","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892434","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}
Conventional camera modules are characterized by a substantial size, thickness, and weight. This is a consequence of the need for multiple lens elements to achieve the required level of image quality. However, as portable electronic devices continue to undergo miniaturization, there is a growing demand for smaller and thinner camera modules. In this paper, the optical characteristics of an ultrasound gel lens were evaluated quantitatively by expanding the wavefront of the transmitted light in terms of the Zernike polynomial. It was possible to control the focal length of the lens by changing its surface profile through the acoustic radiation force generated by ultrasonic vibration. The effects of ultrasound excitation on spherical aberration, coma aberrations, and astigmatisms were investigated. It was observed that spherical and coma aberrations increased with voltage amplitude, while astigmatism exhibited a reduction in magnitude.
{"title":"Optical Characteristics of an Ultrasound Gel Lens","authors":"Haruto Miki;Fumiko Taniguchi;Kosuke Nakamura;Yuki Harada;Mami Matsukawa;Daisuke Koyama","doi":"10.1109/OJUFFC.2025.3561101","DOIUrl":"https://doi.org/10.1109/OJUFFC.2025.3561101","url":null,"abstract":"Conventional camera modules are characterized by a substantial size, thickness, and weight. This is a consequence of the need for multiple lens elements to achieve the required level of image quality. However, as portable electronic devices continue to undergo miniaturization, there is a growing demand for smaller and thinner camera modules. In this paper, the optical characteristics of an ultrasound gel lens were evaluated quantitatively by expanding the wavefront of the transmitted light in terms of the Zernike polynomial. It was possible to control the focal length of the lens by changing its surface profile through the acoustic radiation force generated by ultrasonic vibration. The effects of ultrasound excitation on spherical aberration, coma aberrations, and astigmatisms were investigated. It was observed that spherical and coma aberrations increased with voltage amplitude, while astigmatism exhibited a reduction in magnitude.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"5 ","pages":"48-52"},"PeriodicalIF":0.0,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10965713","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892532","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}
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