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3017 KiB

Open AccessArticle

Systematic Evaluation on Speckle Suppression Methods in Examination of Ultrasound Breast Images

by Xiangfei Feng, Xiaoyu Guo and Qinghua Huang

Appl. Sci. 2017, 7(1), 37; https://doi.org/10.3390/app7010037 - 28 Dec 2016

Cited by 32 | Viewed by 4696

Breast ultrasound is an important tool used in the medical treatment and diagnosis of breast tumor. However, noise defined as speckles are generated inevitably. Although the existence of speckle may be beneficial to diagnosis if used by a well-trained observer, it often causes [...] Read more.

Breast ultrasound is an important tool used in the medical treatment and diagnosis of breast tumor. However, noise defined as speckles are generated inevitably. Although the existence of speckle may be beneficial to diagnosis if used by a well-trained observer, it often causes disturbance which negatively affects clinical diagnosis, not only by reducing resolution and contrast of ultrasound images, but also by adding difficulties to recognize tumor region accurately. In this paper, we investigate a number of popular de-speckling algorithms, including filters based on frequency domain, filters based on local statistical properties, filters based on minimum mean square error (MMSE), and filters based on Partial Differential Equation (PDE). Two visual measurement evaluation criteria, i.e., Mean to Variance Ratio (VMR) and Laplace Response of Domain (LRD), are chosen for the performance comparison of those filters in the application of ultrasound breast image filtering. Moreover, the filtering effect is further evaluated with respect to the segmentation accuracy of tumor regions. According to the evaluation results, we conclude that Bilateral Filter (BF) achieves the best visual effect. Although Weickert J Diffusion (WJD) and Total Variation (TV) can also obtain good visual effect and segmentation accuracy, they are very time-consuming. Full article

(This article belongs to the Special Issue Biomedical Ultrasound)

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4217 KiB

Open AccessArticle

Photoacoustic Tomography Imaging of the Adult Zebrafish by Using Unfocused and Focused High-Frequency Ultrasound Transducers

by Yubin Liu, Dongliang Li and Zhen Yuan

Appl. Sci. 2016, 6(12), 392; https://doi.org/10.3390/app6120392 - 30 Nov 2016

Cited by 15 | Viewed by 6167

Abstract

The zebrafish model provides an essential platform for the study of human diseases or disorders due to the possession of about 87% homologous genes with human. However, it is still very challenging to noninvasively visualize the structure and function of adult zebrafish based [...] Read more.

The zebrafish model provides an essential platform for the study of human diseases or disorders due to the possession of about 87% homologous genes with human. However, it is still very challenging to noninvasively visualize the structure and function of adult zebrafish based on available optical imaging techniques. In this study, photoacoustic tomography (PAT) was utilized for high-resolution imaging of adult zebrafish by using focused and unfocused high-frequency (10 MHz) ultrasound transducers. We examined and compared the imaging results from the two categories of transducers with in vivo experimental tests, in which we discovered that the unfocused transducer is able to identify the inner organs of adult zebrafish with higher contrast but limited regional resolution, whereas the findings from the focused transducer were with high resolution but limited regional contrast for the recovered inner organs. Full article

(This article belongs to the Special Issue Biomedical Ultrasound)

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6705 KiB

Open AccessArticle

Ultrasound Navigation for Transcatheter Aortic Stent Deployment Using Global and Local Information

by Fang Chen, Jia Liu and Hongen Liao

Appl. Sci. 2016, 6(12), 391; https://doi.org/10.3390/app6120391 - 30 Nov 2016

Cited by 1 | Viewed by 6128

Abstract

An ultrasound (US) navigation system using global and local information is presented for transcatheter aortic stent deployment. The system avoids the use of contrast agents and radiation required in traditional fluoroscopically-guided procedures and helps surgeons precisely visualize the surgical site. To obtain a [...] Read more.

An ultrasound (US) navigation system using global and local information is presented for transcatheter aortic stent deployment. The system avoids the use of contrast agents and radiation required in traditional fluoroscopically-guided procedures and helps surgeons precisely visualize the surgical site. To obtain a global 3D (three-dimensional) navigation map, we use magnetic resonance (MR) to provide a 3D context to enhance 2D (two-dimensional) US images through image registration. The US images are further processed to obtain the trajectory of interventional catheter. A high-resolution aortic model is constructed by using trajectory and segmented intravascular ultrasound (IVUS) images. The constructed model reflects morphological characteristics of the aorta to provide local navigation information. Our navigation system was validated using in vitro phantom of heart and aorta. The mean target registration error is 2.70 mm and the average tracking error of the multi-feature particle filter is 0.87 mm. These results confirm that key parts of our navigation system are effective. In the catheter intervention experiment, the vessel reconstruction error of local navigation is reduced by 80% compared to global navigation. Moreover, the targeting error of the navigation combining global and local information is reduced compared to global navigation alone (1.72 mm versus 2.87 mm). Thus, the US navigation system which integrates the large view of global navigation and high accuracy of local navigation can facilitate transcatheter stent deployment. Full article

(This article belongs to the Special Issue Biomedical Ultrasound)

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5379 KiB

Open AccessArticle

A Sibelobe Suppressing Beamformer for Coherent Plane Wave Compounding

by Wei Guo, Yuanyuan Wang and Jinhua Yu

Appl. Sci. 2016, 6(11), 359; https://doi.org/10.3390/app6110359 - 17 Nov 2016

Cited by 16 | Viewed by 5400

Abstract

Contrast degradation is a critical problem in ultrasound plane wave imaging (PWI) resulting from signals leakage from the sidelobes. An ideal sidelobe reduction method may enhance the contrast without remarkably increasing computational load. To this end, we introduce a new singular value decomposition [...] Read more.

Contrast degradation is a critical problem in ultrasound plane wave imaging (PWI) resulting from signals leakage from the sidelobes. An ideal sidelobe reduction method may enhance the contrast without remarkably increasing computational load. To this end, we introduce a new singular value decomposition (SVD) sidelobe reduction beamformer for coherent plane wave compounding (CPWC) based on a previous work. The SVD takes advantage of the benefits of the different features of the mainlobe and sibelobe in terms of spatio-angular coherence and removes the sidelobes before the final coherent summation. This SVD-based method provides a three-dimensional approach (2D in the space and 1D in the angle) while the computation load is kept satisfactory by a dimension-reduced operation before the SVD. To directly observe the sidelobe level, we demonstrate the performance of our SVD method with a point spread function (PSF) simulation. Compared to CPWC, our method shows a 6.2 dB reduction in the peak sidelobe level (PSL). We also applied our method to the anechoic cyst inside the speckle for the imaging contrast. Both in the simulation and phantom studies, our method enhances the contrast-to-noise ratio (CNR) by more than 10%. Therefore, this new beamformer can be an efficient way to suppress sidelobes in PWI. Full article

(This article belongs to the Special Issue Biomedical Ultrasound)

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2822 KiB

Open AccessArticle

The Development of Piezo-Driven Tools for Cellular Piercing

by Changhai Ru, Peng Pan and Ruihua Chen

Appl. Sci. 2016, 6(11), 314; https://doi.org/10.3390/app6110314 - 26 Oct 2016

Cited by 7 | Viewed by 5578

Abstract

Conventionally, intracytoplasmic sperm injection (ICSI) in the mouse is conducted with piezo-drills that use a droplet of mercury for damping. The use of mercury causes concerns of toxicity and contamination. Although Fluorinert can be used as a substitute for mercury to reduce piezo-drill’s [...] Read more.

Conventionally, intracytoplasmic sperm injection (ICSI) in the mouse is conducted with piezo-drills that use a droplet of mercury for damping. The use of mercury causes concerns of toxicity and contamination. Although Fluorinert can be used as a substitute for mercury to reduce piezo-drill’s lateral vibration, the damping effect is not as satisfactory as mercury. In this work, a modified piezo-drill without using mercury was developed for the cellular piercing of mouse oocytes. Experimentally, appropriate parameters of driving voltage and frequency were obtained for the penetration of the zona pellucida of mouse oocytes. Furthermore, the lateral vibration of the injection pipette is lower than 1 μm in deionized water, which is not observable at 400 magnificence. With the piezo-drill without using mercury, the system performs the cellular piercing of mouse oocytes with a maximum cleavage rate of 94.7% (n = 117). Full article

(This article belongs to the Special Issue Biomedical Ultrasound)

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2216 KiB

Open AccessArticle

Numerical Analysis on Cross-Shaped Array with Dynamic Transmit Focusing for Enhanced Volumetric Ultrasound Imaging

by Suhyun Park and Hyun Wook Kang

Appl. Sci. 2016, 6(11), 310; https://doi.org/10.3390/app6110310 - 25 Oct 2016

Cited by 2 | Viewed by 4496

Abstract

Volumetric ultrasound imaging has been primarily used as a clinical tool to diagnose cardiac dysfunction. However, the modality still suffers from system complexity due to a large number of receive channels for volumetric reconstruction. The aim of the study was to numerically assess [...] Read more.

Volumetric ultrasound imaging has been primarily used as a clinical tool to diagnose cardiac dysfunction. However, the modality still suffers from system complexity due to a large number of receive channels for volumetric reconstruction. The aim of the study was to numerically assess a cross-shaped sparse array with a dynamic transmit focusing method to reduce the system complexity and to compensate for the image quality of unfocused volumetric imaging. Analytical simulations with two-way point spread functions demonstrated that the cross-shaped sparse array entailed up to an 84% increase in side-lobes (up to 32 dB), thus leading to significant degradation of the point spread function in the diagonal plane. A dynamic transmit focusing method was able to vividly overcome the image degradation by transmitting more beams with tilting angles. This also yielded a comparable image sensitivity (65 dB) to that of the full array when 31 × 31 tilted waves were used. The proposed cross-shaped sparse array with the dynamic transit focusing method can be used to enhance the frame rate as well as the image quality for unfocused ultrasound imaging. Full article

(This article belongs to the Special Issue Biomedical Ultrasound)

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2038 KiB

Open AccessArticle

Phase-Sensitive 2D Motion Estimators Using Frequency Spectra of Ultrasonic Echoes

by Hideyuki Hasegawa

Appl. Sci. 2016, 6(7), 195; https://doi.org/10.3390/app6070195 - 30 Jun 2016

Cited by 22 | Viewed by 4810

Abstract

Recently, high-frame-rate ultrasound has been extensively studied for measurement of tissue dynamics, such as pulsations of the carotid artery and heart. Motion estimators are very important for such measurements of tissue dynamics. In high-frame-rate ultrasound, the tissue displacement between frames becomes very small [...] Read more.

Recently, high-frame-rate ultrasound has been extensively studied for measurement of tissue dynamics, such as pulsations of the carotid artery and heart. Motion estimators are very important for such measurements of tissue dynamics. In high-frame-rate ultrasound, the tissue displacement between frames becomes very small owing to the high temporal resolution. Under such conditions, the speckle tracking method requires high levels of interpolation to estimate such a small displacement. A phase-sensitive motion estimator is feasible because it does not suffer from the aliasing effect by such a small displacement and does not require interpolation to estimate a sub-sample displacement. In the present study, two phase-sensitive 2D motion estimators, namely, paired 1D motion estimators and 2D motion estimator with shifted cross spectra, were developed. Phase-sensitive motion estimators using frequency spectra of ultrasonic echoes have already been proposed in previous studies. However, such methods had not taken into account the ambiguity of the frequency of each component of the spectrum. We have proposed a method, which estimates the mean frequency of each component of the spectrum, and the proposed method was validated by a phantom experiment. The experimental results showed that the bias errors in the estimated motion velocities of the phantom were less than or equal to (11.5% in lateral, 2.0% in axial) by the proposed 1D paired motion estimators and (3.0%, 2.0%) by the proposed 2D motion estimators, both of which were significantly smaller than (14.0%, 3.0%) of the conventional phase-sensitive 2D motion estimator. Full article

(This article belongs to the Special Issue Biomedical Ultrasound)

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Review

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10684 KiB

Open AccessReview

Enhancement of High-Intensity Focused Ultrasound Heating by Short-Pulse Generated Cavitation

by Shin Yoshizawa, Ryo Takagi and Shin-ichiro Umemura

Appl. Sci. 2017, 7(3), 288; https://doi.org/10.3390/app7030288 - 16 Mar 2017

Cited by 24 | Viewed by 8734

Abstract

A target tissue can be thermally coagulated in high-intensity focused ultrasound (HIFU) treatment noninvasively. HIFU thermal treatments have been clinically applied to various solid tumors. One of the problems in HIFU treatments is a long treatment time. Acoustically driven microbubbles can accelerate the [...] Read more.

A target tissue can be thermally coagulated in high-intensity focused ultrasound (HIFU) treatment noninvasively. HIFU thermal treatments have been clinically applied to various solid tumors. One of the problems in HIFU treatments is a long treatment time. Acoustically driven microbubbles can accelerate the ultrasonic heating, resulting in the significant reduction of the treatment time. In this paper, a method named “trigger HIFU exposure” which employs cavitation microbubbles is introduced and its results are reviewed. A trigger HIFU sequence consists of high-intensity short pulses followed by moderate-intensity long bursts. Cavitation bubbles induced in a multiple focal regions by rapidly scanning the focus of high-intensity pulses enhanced the temperature increase significantly and produced a large coagulation region with high efficiency. Full article

(This article belongs to the Special Issue Biomedical Ultrasound)

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3408 KiB

Open AccessReview

Review of Laser-Generated Ultrasound Transmitters and Their Applications to All-Optical Ultrasound Transducers and Imaging

by Sung-Liang Chen

Appl. Sci. 2017, 7(1), 25; https://doi.org/10.3390/app7010025 - 28 Dec 2016

Cited by 68 | Viewed by 11862

Abstract

Medical ultrasound is an imaging technique that utilizes ultrasonic signals as information carriers, and has wide applications such as seeing internal body structures, finding a source of a disease, and examining pregnant women. The most commonly used ultrasonic transducer today is based on [...] Read more.

Medical ultrasound is an imaging technique that utilizes ultrasonic signals as information carriers, and has wide applications such as seeing internal body structures, finding a source of a disease, and examining pregnant women. The most commonly used ultrasonic transducer today is based on piezoelectricity. The piezoelectric transducer, however, may have a limited bandwidth and insufficient sensitivity for reduced element size. Laser-generated ultrasound (LGUS) technique is an effective way to resolve these issues. The LGUS approach based on photoacoustic effect is able to greatly enhance the bandwidth of ultrasound signals and has the potential for high-resolution imaging. High-amplitude LGUS could also be used for therapy to accomplish high precision surgery without an incision. Furthermore, LGUS in conjunction with optical detection of ultrasound allows all-optical ultrasound imaging (i.e., ultrasound is generated and received optically). The all-optical platform offers unique advantages in providing high-resolution information and in facilitating the construction of miniature probes for endoscopic ultrasound. In this article, a detailed review of the recent development of various LGUS transmitters is presented. In addition, a recent research interest in all-optical ultrasound imaging, as well as its applications, is also discussed. Full article

(This article belongs to the Special Issue Biomedical Ultrasound)

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2586 KiB

Open AccessReview

Advanced Microbubbles as a Multifunctional Platform Combining Imaging and Therapy

by Xianwei Ni, Jinmin Ye, Liping Wang, Shunlong Xu, Chunpeng Zou, Yan Yang and Zhe Liu

Appl. Sci. 2016, 6(11), 365; https://doi.org/10.3390/app6110365 - 21 Nov 2016

Cited by 7 | Viewed by 5566

Abstract

Microbubbles as traditional ultrasound contrast agents have seen tremendous developments and bio-applications in the past decades. Due to their outstanding performance, advanced microbubbles as a multifunctional platform combining both imaging and therapy have been increasingly attracting attention. Associated with ultrasound-mediated stimuli, targeting drug [...] Read more.

Microbubbles as traditional ultrasound contrast agents have seen tremendous developments and bio-applications in the past decades. Due to their outstanding performance, advanced microbubbles as a multifunctional platform combining both imaging and therapy have been increasingly attracting attention. Associated with ultrasound-mediated stimuli, targeting drug transportation with high precision can be established and, as a consequence, a synergistic treatment strategy may prevail, which implies a bright perspective for this brand-new technology. This perspective article will summarize the latest developments on the advanced microbubbles, and review their emerging biomedical applications for the vast community of both applied ultrasound and functional ultrasound-based materials. Full article

(This article belongs to the Special Issue Biomedical Ultrasound)

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