Axial Super-Resolution Ultrasound Imaging With Quasi-Monopolar Pulses From a Dual-Frequency Transducer

Cai, Yiqi; Fan, Mengzhi; Sun, Pengfei; Xu, Lijun; Ma, Jianguo

doi:10.1109/tim.2023.3234032

Cited by 5 publications

(1 citation statement)

References 43 publications

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“…According to the principles of acoustics, when the thickness of the air layer is a multiple of λ/2 (λ is the wavelength), a standing wave will occur at the middle position of the air layer where the incident and reflected waves superimpose. The standing wave will cause resonance phenomena, and resonance will occur when the frequency of the ultrasonic wave is equal to the natural frequency of the air layer [17]. The expression for the resonance angular frequency is:…”

Section: Establishment Of the Mathematical Modelmentioning

confidence: 99%

Measurement of Air Layer Thickness under Multi-Angle Incidence Conditions Based on Ultrasonic Resonance Reflection Theory for Flange Fasteners

2023

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During the servicing of flange fasteners, the sealing gasket and the flange cover interface are prone to separation and air contamination due to factors such as stress, corrosion, and vibration. In the detection process, there are two main issues: firstly, the conventional ultrasonic measurement methods based on the theory of acoustic elasticity are not applicable due to the small thickness of the air layer; secondly, the use of conventional vertical incidence detection methods is difficult to ensure due to the influence of the actual structure. To address these issues, this paper first establishes a mathematical model of ultrasonic resonance reflection, and then calculates the corresponding relationship between the air layer thickness and the resonance frequency under vertical incidence conditions. However, this model is difficult to use to calculate the resonance frequency under different incidence angles. To meet the requirements of different working conditions, a finite element simulation model is further established. By comparing the calculation results of the two models under vertical incidence, the reliability of the established finite element model is verified. The reflection and transmission pressure acoustic field distribution under different incidence angles and air layer thicknesses is simulated, and the function relationship between the incidence angle, air layer thickness, and the corresponding first-order resonance frequency is derived. This enables the measurement of the air layer thickness at any incidence angle, providing technical and theoretical support for practical industrial applications.

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Section: Establishment Of the Mathematical Modelmentioning

confidence: 99%

Measurement of Air Layer Thickness under Multi-Angle Incidence Conditions Based on Ultrasonic Resonance Reflection Theory for Flange Fasteners

2023

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Spectral Ultrasound Combined With Clinical Pathological Parameters in Prediction of Axillary Lymph Node Metastasis in Breast Cancer

Sun,

Han,

et al. 2024

J of Ultrasound Medicine

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ObjectivesTo explore the clinical value of the nomogram based on spectral Doppler ultrasound combined with clinical pathological parameter in predicting axillary lymph node metastasis in breast cancer.MethodsWe prospectively gathered clinicopathologic and ultrasonic data from 240 patients confirmed breast cancer. The risk factors of axillary lymph node metastasis were analyzed by univariate and multivariate logistic regression, and the prediction model was established. The model calibration, predictive ability, and diagnostic efficiency in the training set and the testing set were analyzed by receiver operating characteristic curve and calibration curve analysis, respectively.ResultsUnivariate analysis showed that lymph node metastasis was related with tumor size, Ki‐67, axillary ultrasound, ultrasound spectral quantitative parameter, internal echo, and calcification (P < .05). Multivariate logistic regression analysis showed that the Ki‐67, axillary ultrasound, quantitative parameter (the mean of the mid‐band fit in tumor and posterior tumor) were independent risk factors of axillary lymph node metastasis (P < .05). The models developed using Ki‐67, axillary ultrasound, and quantitative parameters for predicting axillary lymph node metastasis demonstrated an area under the receiver operating characteristic curve of 0.83. Additionally, the prediction model exhibited outstanding predictability for axillary lymph node metastasis, as evidenced by a Harrell C‐index of 0.83 (95% confidence interval 0.73–0.93).ConclusionAxillary ultrasound combined with Ki‐67 and spectral ultrasound parameters has the potential to predict axillary lymph node metastasis in breast cancer, which is superior to axillary ultrasound alone.

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Ultrasound transducers with both imaging and power output capabilities by anti-matching at backing layers

Cai,

Xu,

Zhang

et al. 2024

Applied Physics Letters

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Precise ultrasound therapy requires long-term power output and imaging guidance. However, traditional therapeutic transducers do not have imaging capabilities due to the low bandwidth and long ringing. Whereas for a diagnostic transducer, 20%–30% of the energy is dissipated as heat in the backing layer, resulting in degradation of the transducer under high duty cycle and high voltage excitation. Therefore, the transducers with both power output and imaging capabilities are unmet demands for precise ultrasonic treatment. To address this problem, we propose an ultrasound transducer with both imaging and power output capabilities. An anti-matching layer is designed at the position of the backing layer of the transducer, which reflects the backward ultrasound waves to forward waves. Therefore, the majority of the energy is transmitted efficiently and little energy is dissipated in the backing layer. Finite element simulations demonstrated that a double-layer anti-matching design reflects 99.8% of the backward energy, resulting in an insertion loss of −27.7 dB. The performance was validated by a transducer prototype with transmission measurement using hydrophone and pulse-echo test. This design of transducers with both imaging and power output capabilities indicates a promising application of self-guided ultrasound therapy.

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Axial Super-Resolution Ultrasound Imaging With Quasi-Monopolar Pulses From a Dual-Frequency Transducer

Cited by 5 publications

References 43 publications

Measurement of Air Layer Thickness under Multi-Angle Incidence Conditions Based on Ultrasonic Resonance Reflection Theory for Flange Fasteners

Measurement of Air Layer Thickness under Multi-Angle Incidence Conditions Based on Ultrasonic Resonance Reflection Theory for Flange Fasteners

Spectral Ultrasound Combined With Clinical Pathological Parameters in Prediction of Axillary Lymph Node Metastasis in Breast Cancer

Ultrasound transducers with both imaging and power output capabilities by anti-matching at backing layers

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