Lining Zhang

Bio: Lining Zhang is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Ultrasonic sensor & Transducer. The author has an hindex of 4, co-authored 5 publications receiving 45 citations.

Modulated Excitation Imaging System for Intravascular Ultrasound

Abstract: Advances in methodologies and tools often lead to new insights into cardiovascular diseases. Intravascular ultrasound (IVUS) is a well-established diagnostic method that provides high-resolution images of the vessel wall and atherosclerotic plaques. High-frequency (>50 MHz) ultrasound enables the spatial resolution of IVUS to approach that of optical imaging methods. However, the penetration depth decreases when using higher imaging frequencies due to the greater acoustic attenuation. An imaging method that improves the penetration depth of high-resolution IVUS would, therefore, be of major clinical importance. Modulated excitation imaging is known to allow ultrasound waves to penetrate further. This paper presents an ultrasound system specifically for modulated-excitation-based IVUS imaging. The system incorporates a high-voltage waveform generator and an image processing board that are optimized for IVUS applications. In addition, a miniaturized ultrasound transducer has been constructed using a Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystal to improve the ultrasound characteristics. The results show that the proposed system was able to provide increases of 86.7% in penetration depth and 9.6 dB in the signal-to-noise ratio for 60 MHz IVUS. In vitro tissue samples were also investigated to demonstrate the performance of the system.

Dual-frequency intravascular ultrasonic imaging probe

Abstract: Disclosed is a dual-frequency intravascular ultrasonic imaging probe (3), comprising a low-frequency ultrasonic transducer (4a) and a high-frequency ultrasonic transducer (4b) for generating ultrasound to perform imaging simultaneously or at different times and simultaneously connecting the two ultrasonic transducers (4a, 4b) via a coaxial cable (23). During operation, the probe (3), by using a low-frequency single array element transducer and a high-frequency single array element transducer, can send an excitation signal to the two transducers (4a, 4b) simultaneously or at different times, so as to enable the transducers (4a, 4b) to transmit and receive ultrasonic wave, and at a later stage perform processing such as filtering on the signal received by the transducers (4a, 4b) to simultaneously acquire a low-frequency and a high-frequency ultrasound image. Furthermore, the probe (3) uses the two transducers (4a, 4b) whilst using only one coaxial cable (23), such that the external size is not enlarged relative to a single array element mechanical catheter, and a tail part of a catheter (2) similarly only needs one rotary retraction device and one signal port.

Dual-transducer intravascular ultrasonic imaging device

Abstract: Disclosed is a dual-transducer intravascular ultrasonic imaging device, comprising a catheter (2) and an ultrasonic probe (3) located at a front end of the catheter (2), wherein the catheter (2) comprises a protective tube (21), a flexible metal pipe (22) and a coaxial cable (23); and the ultrasonic probe (3) is located in the protective tube (21), the ultrasonic probe (3) comprises two ultrasonic transducers (4), the two ultrasonic transducers (4) are arranged back to back and send, simultaneously or at different times, ultrasonic beams for imaging, and the two ultrasonic transducers (4) have a common backing layer (43). The device of the present invention comprises the two high-frequency single-array-element transducers, and during operation, the two transducers can simultaneously transmit and receive an ultrasonic wave so as to obtain more intravascular tissue information. In addition, the two ultrasonic transducers (4) of the present invention share the backing layer (43), such that the thickness of each transducer of a multi-layer structure can be greatly decreased, thereby greatly improving the practicability of the device.

Multifunctional intravascular ultrasonic imaging device

Abstract: The invention provides a multifunctional intravascular ultrasonic imaging device which comprises a catheter and an ultrasonic probe located at the front end of the catheter. The ultrasonic probe is provided with a housing, one or more front-viewing imaging transducers and one or more slant-viewing imaging transducers, wherein the front-viewing imaging transducers and the slant-viewing imaging transducers are fixed in the housing, the front-viewing imaging transducers are used for conducting ultrasonic imaging on a vascular atherosclerotic plaque to detect the form of the plaque, the slant-viewing imaging transducers are used for performing blood flow imaging to detect the speed of blood flow nearby the plaque and the form of the plaque at multiple angles, the front-viewing imaging transducers are arranged in the axial direction parallel to the housing, the slant-viewing imaging transducers are arranged at certain angles with the front-viewing imaging transducers, and accordingly tissueimaging and blood flow imaging at different angles are performed. The multifunctional intravascular ultrasonic imaging device can detect the blood flow information nearby the imaged tissues while tissue imaging. The transducers can perform tissue imaging at multiple angles and can perform plaque imaging multidimensionally.

Ultrasonic transducer, focused transducer and focused transducer manufacturing method

Abstract: The invention provides an ultrasonic transducer, a focused transducer and a focused transducer manufacturing method and relates to the technical field of ultrasonic detection. The ultrasonic transducer comprises a tube sleeve; at least two piezoelectric components are dispersedly disposed in the tube sleeve; the piezoelectric component comprises a piezoelectric vibrator and a matching layer, wherein the matching layer is located on the same end of the tube sleeve, and the frequency of the piezoelectric vibrator is not the same. The focused transducer comprises the above-mentioned ultrasonic transducer, and the matching layer forms a concave spherical surface in the tube sleeve. The focused transducer manufacturing method includes the following steps of heating and softening insulating filler, pressing the piezoelectric component with a part of a convex spherical surface until the piezoelectric component is recessed in the insulating filler and forms a concave spherical surface, coolingand solidifying the insulating filler, and then taking out the part of the convex spherical surface. With the piezoelectric vibrator in the piezoelectric component of different frequency, the frequency of the obtained corresponding ultrasonic wave is also different, and thus, the ultrasonic transducer is widened to obtain ultrasonic frequency bandwidth, and application range and practicality thereof are increased.

Machine Learning in Ultrasound Computer-Aided Diagnostic Systems: A Survey.

Abstract: The ultrasound imaging is one of the most common schemes to detect diseases in the clinical practice. There are many advantages of ultrasound imaging such as safety, convenience, and low cost. However, reading ultrasound imaging is not easy. To support the diagnosis of clinicians and reduce the load of doctors, many ultrasound computer-aided diagnosis (CAD) systems are proposed. In recent years, the success of deep learning in the image classification and segmentation led to more and more scholars realizing the potential of performance improvement brought by utilizing the deep learning in the ultrasound CAD system. This paper summarized the research which focuses on the ultrasound CAD system utilizing machine learning technology in recent years. This study divided the ultrasound CAD system into two categories. One is the traditional ultrasound CAD system which employed the manmade feature and the other is the deep learning ultrasound CAD system. The major feature and the classifier employed by the traditional ultrasound CAD system are introduced. As for the deep learning ultrasound CAD, newest applications are summarized. This paper will be useful for researchers who focus on the ultrasound CAD system.

Power MOSFET Linearizer of a High-Voltage Power Amplifier for High-Frequency Pulse-Echo Instrumentation

Abstract: A power MOSFET linearizer is proposed for a high-voltage power amplifier (HVPA) used in high-frequency pulse-echo instrumentation. The power MOSFET linearizer is composed of a DC bias-controlled series power MOSFET shunt with parallel inductors and capacitors. The proposed scheme is designed to improve the gain deviation characteristics of the HVPA at higher input powers. By controlling the MOSFET bias voltage in the linearizer, the gain reduction into the HVPA was compensated, thereby reducing the echo harmonic distortion components generated by the ultrasonic transducers. In order to verify the performance improvement of the HVPA implementing the power MOSFET linearizer, we measured and found that the gain deviation of the power MOSFET linearizer integrated with HVPA under 10 V DC bias voltage was reduced (−1.8 and −0.96 dB, respectively) compared to that of the HVPA without the power MOSFET linearizer (−2.95 and −3.0 dB, respectively) when 70 and 80 MHz, three-cycle, and 26 dBm input pulse waveforms are applied, respectively. The input 1-dB compression point (an index of linearity) of the HVPA with power MOSFET linearizer (24.17 and 26.19 dBm at 70 and 80 MHz, respectively) at 10 V DC bias voltage was increased compared to that of HVPA without the power MOSFET linearizer (22.03 and 22.13 dBm at 70 and 80 MHz, respectively). To further verify the reduction of the echo harmonic distortion components generated by the ultrasonic transducers, the pulse-echo responses in the pulse-echo instrumentation were compared when using HVPA with and without the power MOSFET linearizer. When three-cycle 26 dBm input power was applied, the second, third, fourth, and fifth harmonic distortion components of a 75 MHz transducer driven by the HVPA with power MOSFET linearizer (−48.34, −44.21, −48.34, and −46.56 dB, respectively) were lower than that of the HVPA without the power MOSFET linearizer (−45.61, −41.57, −45.01, and −45.51 dB, respectively). When five-cycle 20 dBm input power was applied, the second, third, fourth, and fifth harmonic distortions of the HVPA with the power MOSFET linearizer (−41.54, −41.80, −48.86, and −46.27 dB, respectively) were also lower than that of the HVPA without the power MOSFET linearizer (−25.85, −43.56, −49.04, and −49.24 dB, respectively). Therefore, we conclude that the power MOSFET linearizer could reduce gain deviation of the HVPA, thus reducing the echo signal harmonic distortions generated by the high-frequency ultrasonic transducers in pulse-echo instrumentation.

Development of a Multiwavelength Visible-Range-Supported Opto⁻Ultrasound Instrument Using a Light-Emitting Diode and Ultrasound Transducer.

Abstract: A new multiwavelength visible-range-supported opto⁻ultrasound instrument using a light-emitting diode and ultrasound transducer was developed in order to produce multiwavelength visible light with minimized color aberration errors, and detect ultrasound signals emitted from the target. In the instrument, the developed optical systems can provide multiwavelength optical transmission with low optical aberration within 10-cm ranges that are reasonably flat in the modulation transfer function at spatial frequencies of 20 and 40 lp/mm, except at the end of the diagonal edge of the samples. To assess the instrument capability, we performed pulse⁻echo responses with Thunnus obesus eye samples. Focused red, green, blue and white light rays from an integrated red, green and blue LED source were produced, and echo signal amplitudes of 33.53, 34.92, 38.74 and 82.54 mV, respectively, were detected from the Thunnus obesus eye samples by a 10-MHz focused ultrasound transducer. The center frequencies of the echo signal when producing red, green, blue and white LED light in the instrument were 9.02, 9.05, 9.21 and 8.81 MHz, respectively. From these tests, we verify that this instrument can combine red, green and blue LED light to cover different wavelengths in the visible-light range and detect reasonable echo amplitudes from the samples.

Development of a Mechanical Scanning Device With High-Frequency Ultrasound Transducer for Ultrasonic Capsule Endoscopy

Abstract: Wireless capsule endoscopy has opened a new era by enabling remote diagnostic assessment of the gastrointestinal tract in a painless procedure. Video capsule endoscopy is currently commercially available worldwide. However, it is limited to visualization of superficial tissue. Ultrasound (US) imaging is a complementary solution as it is capable of acquiring transmural information from the tissue wall. This paper presents a mechanical scanning device incorporating a high-frequency transducer specifically as a proof of concept for US capsule endoscopy (USCE), providing information that may usefully assist future research. A rotary solenoid-coil-based motor was employed to rotate the US transducer with sectional electronic control. A set of gears was used to convert the sectional rotation to circular rotation. A single-element focused US transducer with 39-MHz center frequency was used for high-resolution US imaging, connected to an imaging platform for pulse generation and image processing. Key parameters of US imaging for USCE applications were evaluated. Wire phantom imaging and tissue phantom imaging have been conducted to evaluate the performance of the proposed method. A porcine small intestine specimen was also used for imaging evaluation in vitro . Test results demonstrate that the proposed device and rotation mechanism are able to offer good image resolution ( $\sim 60~\mu \text{m}$ ) of the lumen wall, and they, therefore, offer a viable basis for the fabrication of a USCE device.

Recent Advances in Transducers for Intravascular Ultrasound (IVUS) Imaging

Abstract: As a well-known medical imaging methodology, intravascular ultrasound (IVUS) imaging plays a critical role in diagnosis, treatment guidance and post-treatment assessment of coronary artery diseases. By cannulating a miniature ultrasound transducer mounted catheter into an artery, the vessel lumen opening, vessel wall morphology and other associated blood and vessel properties can be precisely assessed in IVUS imaging. Ultrasound transducer, as the key component of an IVUS system, is critical in determining the IVUS imaging performance. In recent years, a wide range of achievements in ultrasound transducers have been reported for IVUS imaging applications. Herein, a comprehensive review is given on recent advances in ultrasound transducers for IVUS imaging. Firstly, a fundamental understanding of IVUS imaging principle, evaluation parameters and IVUS catheter are summarized. Secondly, three different types of ultrasound transducers (piezoelectric ultrasound transducer, piezoelectric micromachined ultrasound transducer and capacitive micromachined ultrasound transducer) for IVUS imaging are presented. Particularly, the recent advances in piezoelectric ultrasound transducer for IVUS imaging are extensively examined according to their different working mechanisms, configurations and materials adopted. Thirdly, IVUS-based multimodality intravascular imaging of atherosclerotic plaque is discussed. Finally, summary and perspectives on the future studies are highlighted for IVUS imaging applications.