Synthetic aperture ultrasound imaging with a ring transducer array: preliminary ex vivo results

Qu, Xiaolei; Azuma, Takashi; Yogi, Takeshi; Azuma, Shiho; Takeuchi, Hideki; Tamano, Satoshi; Takagi, Shu

doi:10.1007/s10396-016-0724-y

Cited by 29 publications

(21 citation statements)

References 29 publications

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“…The schematic diagram of echo imaging using the SA method is illustrated in Figure 3. The SA method can implement both dynamic-transmit and dynamic-receive focusing and provide high quality echo images [18,36].…”

Section: B Echo Imaging By Sa Methods Figure 3 Schematic Diagram Of mentioning

confidence: 99%

“…USCT can automatically and non-invasively obtain 3D breast images in three different modalities, namely echo image, sound speed image (SSI), and attenuation image. The USCT imaging system can be built based on conventional linear transducer array [10][11][12][13][14][15][16] or the ring transducer array [17][18]. In this study, the system is based on the ring transducer array, which generally includes a table with an opening on it, a water tank under the opening of the table, and a ring transducer array immersed in the water tank.…”

Section: Introductionmentioning

confidence: 99%

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A Combined Regularization Method Using Prior Structural Information for Sound-Speed Image Reconstruction of Ultrasound Computed Tomography

et al. 2020

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Ultrasound computed tomography (USCT) is a promising technique for breast imaging. It provides three modalities: echo image, sound speed image (SSI), and attenuation image. The echo image reveals structural details of the breast with high resolution but is not quantitative. The SSI is quantitative, but its resolution is generally lower than that of the echo image. The SSI reconstruction is an ill-posed problem, thus the Tikhonov or total variation (TV) regularization methods are generally used. Tikhonov regularization is stable, but it tends to smooth the SSI and results in low resolution. TV regularization can preserve the sharp edges and provide higher resolution, but it may result in staircase artifacts. To combine the advantages of Tikhonov and TV regularizations, this article proposes a combined regularization method using prior structural information from the echo image. The proposed method mainly includes three steps. First, the echo image is reconstructed using the synthetic aperture (SA) technique and then segmented into breast and water regions. The segmentation result is used as prior structural information. Second, the USCT sound propagation forward model was built. Finally, with a penalty term according to the prior structural information, the combined regularization method is used to reconstruct the SSI. Both simulation and ex vivo experiments were conducted for evaluation. In the simulation, the proposed method has a low root-mean-square-error (13.78 m/s), a high correlation coefficient (0.812), a high structural similarity (0.755), and a low standard deviation of water sound speed (2.33 m/s). In the ex vivo experiment, the method has a low standard deviation of water sound speed (1.44 and 3.13 m/s for small and large objects, respectively), a low contrast to noise ratio (3.09 and 5.08), and a high Dice coefficient (0.92 and 0.97). Thus, the proposed combined regularization method using prior structural information can improve reconstruction quality.

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Section: B Echo Imaging By Sa Methods Figure 3 Schematic Diagram Of mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Combined Regularization Method Using Prior Structural Information for Sound-Speed Image Reconstruction of Ultrasound Computed Tomography

et al. 2020

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“…Ultrasound-computed tomography (USCT) systems capture both reflected and transmitted ultrasound signals [ 1 , 2 , 3 , 4 ]. The reflected signals are used to generate the reflection image, also known as the B-mode image of the hand-held ultrasound, while the transmitted signals are utilized to reconstruct the sound speed (SS) image and attenuation image [ 5 , 6 , 7 , 8 ]. The SS image and attenuation image can provide quantitative information [ 9 , 10 ] for diagnosis, e.g., a breast tumor normally has higher SS and attenuation coefficient than normal tissues [ 11 , 12 , 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Zone-Shrinking Fresnel Zone Travel-Time Tomography for Sound Speed Reconstruction in Breast USCT

Fang

Song

et al. 2020

Sensors

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Many studies have been carried out on ultrasound computed tomography (USCT) for its potential application in breast imaging. The sound speed (SS) image modality in USCT can help doctors diagnose the breast cancer, as the tumor usually has a higher sound speed than normal tissues. Travel time is commonly used to reconstruct SS image. Raypath travel-time tomography (RTT) assumes that the sound wave travels through a raypath. RTT is computationally efficient but with low contrast to noise ratio (CNR). Fresnel zone travel-time tomography (FZTT) is based on the assumption that the sound wave travels through an area called the Fresnel zone. FZTT can provide SS image with high CNR but low accuracy due to the wide Fresnel zone. Here, we propose a zone-shrinking Fresnel zone travel-time tomography (ZSFZTT), where a weighting factor is adopted to shrink the Fresnel zone during the inversion process. Numerical phantom and in vivo breast experiments were performed with ZSFZTT, FZTT, and RTT. In the numerical experiment, the reconstruction biases of size by ZSFZTT, FZTT, and RTT were 0.2%~8.3%, 2.3%~31.7%, and 1.8%~25%; the reconstruction biases of relative SS value by ZSFZTT, FZTT, and RTT were 24.7%~42%, 53%~60.8%, and 30.3%~47.8%; and the CNR by ZSFZTT, FZTT, and RTT were 67.7~96.6, 68.5~98, and 1.7~2.7. In the in vivo breast experiment, ZSFZTT provided the highest CNR of 8.6 compared to 8.1 by FZTT and 1.9 by RTT. ZSFZTT improved the reconstruction accuracy of size and the relative reconstruction accuracy of SS value compared to FZTT and RTT while maintaining a high CNR similar to that of FZTT.

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“…Additionally, the scanning in traditional imaging based on a linear or convex probe is highly operator-dependent, which may easily introduce misdiagnosis due to scanning inappropriate planes. The ring array can naturally solve or produce some improvement in these problems because of its geometrical structure [1]. The ring array can receive not only the echo wave but also the scatter wave and transmission wave in different directions at the same time.…”

Section: Introductionmentioning

confidence: 99%

“…The ring array can receive not only the echo wave but also the scatter wave and transmission wave in different directions at the same time. Imaging with a ring array, we can get the structure information with the echo wave [1], as well as the maps of speed of sound and attenuation with the transmission wave [2–7]. Combining the above advantages, ultrasound computed tomography (USCT) has received increasing attention.…”

Section: Introductionmentioning

confidence: 99%

Plane wave imaging combined with eigenspace-based minimum variance beamforming using a ring array in ultrasound computed tomography

et al. 2019

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BackgroundUltrasound computed tomography (USCT) is usually realized with a ring array. It can provide better imaging performance and more tissue information by emitting and receiving the ultrasound signal in different directions simultaneously. However, USCT imaging is usually applied with the synthetic aperture (SA) emission method, which leads to a long scanning time with a large number of elements on the ring array. The echo image can provide the structural information, and has a higher resolution than maps of other parameters in USCT. Hence, we proposed plane wave (PW) imaging for ring array to acquire the echo wave and reduce the scanning time considerably.ResultsIn this paper, an emitting and receiving process was proposed to realize plane wave imaging with a ring array. With the proposed scanning method, the number of emission events can be reduced greatly. A beamforming method based on the eigenspace-based minimum variance (ESBMV) was also combined with the scanning method. With ESBMV beamformer, the resolution and contrast ratio of reconstruction result can be maintained or even improved under a fewer-emissions condition. We validated the method using both computer simulations with Field II and phantom experiments with a ring array of 512 elements. The Verasonics® system was used to transmit and receive the ultrasound signal in the phantom experiments.ConclusionsAccording to the results of the experiments, the imaging results will have a better contrast ratio with a higher emitting energy. Additionally, the scanning time with the proposed method can be only one-tenth of that with the SA emission method, while the echo imaging performance still remains at a similar level or even better.

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Synthetic aperture ultrasound imaging with a ring transducer array: preliminary ex vivo results

Abstract: The proposed ring transducer array and SA ultrasound imaging method were shown to be capable of producing isotropic high-resolution images whose quality was independent of depth.

Cited by 29 publications

References 29 publications

A Combined Regularization Method Using Prior Structural Information for Sound-Speed Image Reconstruction of Ultrasound Computed Tomography

A Combined Regularization Method Using Prior Structural Information for Sound-Speed Image Reconstruction of Ultrasound Computed Tomography

Zone-Shrinking Fresnel Zone Travel-Time Tomography for Sound Speed Reconstruction in Breast USCT

Plane wave imaging combined with eigenspace-based minimum variance beamforming using a ring array in ultrasound computed tomography

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