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Construction of smart city has become a historical trend in the world. The management of underground pipes and the intelligent concrete are the main part of building smart city in China. Compared with the available electronic marker system, SAW-RFID system has shown excellent properties: truly passive, strong penetrating capability, long service-life, sensing and ID integration, and etc. Thus, SAW-RFID...
It is critical to use a proper spatial sampling, otherwise images suffer from grating lobes. However, the cost of a medical ultrasound scanner is strongly related to the channel count of the receive electronics. This has led to channel reduction using multiplexing or in-probe pre-beamforming methods at the cost of image quality or frame rate. An alternative is to reduce the receive channel count and...
Harmonic imaging techniques are widely used in B-mode abdominal imaging and motion tracking in shear wave elasticity imaging (SWEI) to reduce clutter and improve data quality. Harmonic imaging can be both signal-to-noise (SNR) and penetration depth (PD) limited, resulting in decreased diagnostic utility. This work evaluates B-mode harmonic imaging and SWEI harmonic tracking data quality between imaging...
Arbitrary excitation waveforms are desirable in HIFU array systems. In trans-skull therapy this is necessary to compensate for phase aberrations and achieve even heating of the skull. To facilitate this, wave form generators and large, costly class A RF amplifiers are used. High element counts are commonplace and so the portability of these systems is greatly reduced. We propose using switched mode...
Pancreatic cancer is associated with poor clinical outcomes primarily, due to the advanced stage of disease at diagnosis. Harmonic contrast-enhanced endoscopic ultrasound has been proposed as an imaging approach for characterizing pancreatic masses. As an alternative, transabdominal subharmonic imaging has been proposed to limit invasiveness and better suppress nonlinear tissue echoes. In both of...
To overcome the low sensitivity of current breast imaging tools, new tools for breast imaging and evaluation must be developed for reliable identification and differentiation of breast masses based on stiffness. Recently, we have shown that Harmonic Motion Imaging (HMI) can be used to differentiate relative stiffness and monitor HIFU ablations in small lumpectomy human breast specimens. The objective...
Transmit filters comprising piezoelectric resonators are fabricated in a Thin Film Bulk Acoustic Resonator (FBAR) technology. A filter's 2nd harmonic emissions (H2), generated by the resonators in the filter's output stage must be sufficiently small to prevent the filter from desensitizing a nearby receiver. Anti-parallel and anti-series connected resonator configurations, in which the H2 emissions...
Tissue harmonic imaging, an essential mode of ultrasound imaging scanners, can provide images with high spatial and contrast resolutions. However, it is difficult to use this imaging mode in intravascular ultrasound (IVUS) imaging. This is so because typical IVUS transducers are operated at high frequency (>20 MHz) and have a narrow fractional bandwidth (about 50%). Due to its small aperture (about...
Kidney cancer is a severe disease which can be treated by using a non-invasive, controllable and focused ultrasound surgery method-histotripsy. Previously, histotripsy produced by hundred-microsecond-long focused ultrasound pulses has been proposed by us, which generates mechanical homogenized lesion by employing boiling bubbles and high duty cycle compared with conventional methods. However, the...
In magnetomotive (MM) ultrasound (US) imaging, magnetic nanoparticle (MNP) labeled tissue is moved by a magnetically induced force. Therefore, all MNPs in the field of view are excited simultaneously and a high field strength results in magnetic saturation of MNPs, hence, in a linear response. The linear displacements are spatially resolved by US tracking methods. Recently [1], it was proposed to...
Ultrafast ultrasound imaging offers great opportunities to new imaging technologies such as shear wave elastography and ultrafast Doppler. Multiplane wave (MW) imaging is a new technique in which multiple positively or negatively encoded plane waves are emitted successively with short interleaved time during one transmission event (i.e. pulse-echo event), aiming at increasing the signal-to-noise ratio...
Assessment of medium nonlinearity parameter in pulse-echo mode usually demands information on the second harmonic. However, the acquisition of quantitative data on backscattered amplitude at the fundamental and second harmonic components is difficult using the same probe due to its limited bandwidth. In this paper we propose how to assess medium nonlinearity using only the fundamental harmonic and...
Pancreatic ductal adenocarcinoma (PDA) has one of the lowest prognosis due to non-specific symptoms leading to late diagnosis. The tumor is characterized by an unusually dense stroma limiting chemotherapeutic perfusion. Harmonic Motion Imaging (HMI) assesses tissue mechanical properties by inducing localized oscillation resulting from a periodic acoustic radiation force. The amplitude of the displacement...
Filters operated at high power levels and comprising BAW resonators produce 2nd harmonic emissions. To model the emissions of a BAW resonator, Feld and Shim constructed a nonlinear Mason model, which implements an “extended” pair of piezoelectric constitutive equations containing arbitrary 2nd order terms: T = cES − eE + [1/2δ3cES2 − δ1eSE + 1/2δ2εSE2] D = eS + εSE + [1/2δ1eS2 − δ2εSSE +1/2δ4εSeE2...
Contrast of echographic images has been highly improved by the injection of ultrasound contrast agents that consist of gaz microbubbles. The improvement is due to the nonlinearity of microbubbles, i.e. when excited with a frequency f0, they can generate harmonics at (2f0, 3f0, …). However, the contrast improvement is limited by the nonlinear ultrasound propagation in tissue. To overcome this drawback,...
With ever increasing requirements on the linearity of SAW signal processing devices in mobile communication, nonlinear effects like harmonic generation and intermodulations have gained renewed interest and have become an active field of research with the aim of identifying their origin, analyzing and counteracting them. In this contribution we focus on second-harmonic generation in SAW resonators...
Power handling is a topic of considerable interest in the ultrasonics community as it affects the performance of acoustic devices across multiple fields of study including frequency control, transducers, and NDT / NDE. Harmonic finite element simulations are widely used to model the steady-state linear response of such devices; however, the underlying formulation assumes constant (or frequency-dependent)...
Fetal short-lag spatial coherence (SLSC) imaging has demonstrated 64–85% increases in CNR and 17–29% increases in contrast relative to conventional B-mode imaging. However, despite its proven technical efficacy, the viability of fetal SLSC in the clinical setting remains unknown. The aims of this study were: 1) To demonstrate the feasibility of real-time SLSC imaging on existing hardware and 2) to...
Stress echocardiography is an ultrasound imaging technique to assess the functionality of wall segments of the left ventricle (LV). However, image quality is inadequate in up to 30% of patients, requiring the administration of contrast agents. Coherence-based beamforming methods have shown promise in improving image quality by mitigating clutter, a major source of image degradation. In a previous...
Nonlinear shear waves have a cubic nonlinearity which generates a unique odd harmonic signature. This behavior was first observed in a homogeneous gelatin phantom with ultrafast plane wave compounding ultrasound imaging and correlation-based tracking algorithm that determines particle motion. However, in heterogeneous tissue, like brain, clutter degrades motion tracking and destroys the weak odd harmonics...
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