Jingjing Xia

Bio: Jingjing Xia is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Ultrasound & Ultrasonic sensor. The author has an hindex of 3, 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.

Evaluation of Brain Tumor in Small Animals Using Plane Wave-Based Power Doppler Imaging.

Abstract: Precisely evaluating the characteristics of a glioma tumor in vivo is challenging when performing surgical resection clinically. The infiltration characteristics of a tumor make precise resection difficult because of uncertainties about the surrounding vasculature and the relationships with functional structures. Magnetic resonance imaging is routinely used to distinguish the area of a glioma, but it cannot resolve details of the vascular network around or inside the tumor. Ultrasound imaging is a real-time imaging modality that has been applied clinically in intra-operative surgery, and the sensitivity of flow measurements in the brain is improved by ultrafast plane wave imaging. This study applies a plane wave-based power Doppler imaging method to visualize the blood flow distribution in glioma models in vivo. This new imaging method makes it possible to delineate the flow structure of a glioma tumor in the brain of a small animal. The tumor can be distinguished from normal brain tissue, and different sections of the tumor contain different flow structures. The normalized blood flow intensities (mean ± standard deviation) within regions of interest were 0.33 ± 0.13, 0.72 ± 0.15, 0.36 ± 0.23 and 0.06 ± 0.07 for the type I normal rat, type I glioma rat, type II normal rat and type II glioma rat, respectively. Quantification analysis verified the feasibility of using this plane wave-based Doppler imaging method to evaluate brain tumors in small animals.

A Delayed-Excitation Data Acquisition Method for High-Frequency Ultrasound Imaging

Abstract: High-frequency ultrasound imaging (at >20 MHz) has gained widespread attention due to its high spatial resolution being useful for basic cardiovascular and cancer research involving small animals. The sampling rate of the analog-to-digital converter in a high-frequency ultrasound system usually needs to be higher than 120 MHz in order to satisfy the Nyquist sampling-rate requirement. However, the sampling rate is typically within the range of 40–60 MHz in a traditional ultrasound system, and so we propose a delayed-excitation method for performing high-frequency ultrasound imaging with a traditional data acquisition scheme. In this method, the transmitted pulse is delayed by a certain time period so that the ultrasound echo data are aligned into high-sampling-rate slots. Wire and tissue-mimicking phantoms were imaged to evaluate the performance of the proposed method, whereas a porcine small-intestine specimen and an excised rabbit eyeball were used for in vitro imaging evaluations. The test results demonstrate that the proposed method allows high-frequency ultrasound imaging to be implemented using a traditional ultrasound sampling system.

Method and device for processing uniformity and contrast of ultrasonic images

Abstract: The invention belongs to the field of medical imaging, and provides a method and a device for processing uniformity and contrast of ultrasonic images, in order to improve imaging quality of the ultrasonic images and meet medical imaging requirements. The method includes preprocessing input ultrasonic image data to acquire the preprocessed ultrasonic image data; partitioning the preprocessed ultrasonic image data into a characteristic region and a non-characteristic region to acquire a partitioned image; selecting different gray-scale mapping curves to perform grey scale adjustment on the characteristic region and the non-characteristic region in the partitioned image, and outputting the partitioned image to a display device for display. Compared with the prior, the method and the device have the advantages that images can be partitioned effectively,, and contrast of characteristic information can be increased; due to symmetry of a grey-scale mapping curve group, the contrast of the characteristic region and the uniformity of the non-characteristic region can be fused perfectly, and good image effect is achieved on the premise of low dependence on image partition.

Effects of Non-Elevation-Focalized Linear Array Transducer on Ultrasound Plane-Wave Imaging

Abstract: Plane-wave ultrasound imaging (PWUS) has become an important method of ultrasound imaging in recent years as its frame rate has exceeded 10,000 frames per second, allowing ultrasound to be used for two-dimensional shear wave detection and functional brain imaging. However, compared to the traditional focusing and scanning method, PWUS images always suffer from a degradation of lateral resolution and contrast. To improve the image quality of PWUS, many different beamforming algorithms have been proposed and verified. Yet the influence of transducer structure is rarely studied. For this paper, the influence of using an acoustic lens for PWUS was evaluated. Two linear array transducers were fabricated. One was not self-focalized in the elevation direction (non-elevation-focalized transducer, NEFT); the other one was a traditional elevation-focalized transducer (EFT). An initial simulation was conducted to show the influence of elevation focusing. Then the images obtained with NEFT on a standard ultrasound imaging phantom were compared with those obtained with EFT. It was demonstrated that, in a relatively deep region, the contrast of an NEFT image is better than that of an EFT image. These results indicate that a more sophisticated design of ultrasound transducer would further improve the image quality of PWUS.

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.

3D Printing of BaTiO3 Piezoelectric Ceramics for a Focused Ultrasonic Array

Abstract: BaTiO3 (BTO) ceramics were fabricated based on stereolithography technology. The microstructures and electric properties of the BTO ceramics were studied. X-ray patterns of sintered BTO ceramics indicated that the tetragonal phase had formed, and the grain size increased clearly as BTO weight percentage increased. Moreover, the BTO ceramics exhibited good electric properties, with a piezoelectric constant d33 of 166 pC/N at 80% BTO weight percentage. To evaluate the properties of 3D printed BTO ceramics, a 1.4 MHz focused ultrasonic array was fabricated and characterized. The −6dB bandwidth of the array was 40%, and the insertion loss at the center frequency was 50 dB. The results show that the printed BTO ceramics array have good potential to be used in ultrasonic transducers for various applications.

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.