• Journal of Biomedical Engineering Research
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• v.30 no.3
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• pp.233-240
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• 2009

Using a spatial compound imaging technique in a medical ultrasound imaging system, the average speed of sound in a medium of interest is measured, and imaging of its distribution is implemented. When the brightness reaches the highest level in an ultrasonic image obtained as the speed of sound used in focusing is varied, it turns out that the focusing has been accomplished satisfactorily and that the speed of sound which has been adopted becomes the sought-after average speed of sound. Because spatial compound imaging provides many different views of the same object, the adverse effect of erroneous speed-of-sound estimation tends to be more severe in compound imaging than in plain B-mode imaging. Thus, in compound imaging, the average speed of sound even in the case of speckled images can be accurately estimated by observing the brightness change due to different speeds of sound employed. Using this new method that offers spatial diversity, we can construct an image of the speed of sound distribution in a phantom embedded with a 10-mm diameter plastic cylinder whose speed of sound is different from that of the background. The speed of sound in the cylinder is found to be different from that of the surrounding medium.

• Proceedings of the Korea Contents Association Conference
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• 2014.11a
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• pp.433-434
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• 2014

최근 간질환 검사의 비침습적인 방법으로 탄성초음파가 각광받고 있는 추세이다. 그러나 진단결과와 탄성초음파 결과 값에 따른 표준 진단 매뉴얼이 없는 실정이다. 따라서 본 연구에서는 탄성초음파 수치에 따른 간질환의 종류와 B-mode 영상 간의 경향을 알아보고자 하였다. 그리고 환자의 우측 늑간 초음파 B-mode 영상평가 파라미터인 평균, 신호 대 잡음비, 최대신호 대 잡음비, 엔트로피로 분석하고, 동일 부위에 시행한 탄성초음파 수치와의 비교를 통해 경향을 연구하였고, 그 기준을 제시하고자 하였다.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.484-493
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• 2012

Since the 1980s, there have been many research activities devoted to quantitatively characterizing and imaging human tissues based on sound speed, attenuation coefficient, density, nonlinear B/A parameter, etc., but those efforts have not yet reached the stage of commercialization. However, a new imaging technology termed elastography, which was proposed in the early 1980s, has recently been implemented in commercial clinical ultrasound scanners, and is now being used to diagnose prostates, breasts, thyroids, livers, blood vessels, etc., more quantitatively as a complementary adjunct modality to the conventional B-mode imaging. The purpose of this article is to introduce and review various elastographic algorithms for use in quasistatic or static compression type elasticity imaging modes. Most of the algorithms are based on the crosscorrelation or autocorrelation function methods, and the fundamental difference is that the time shift is estimated by changing the lag variable in the former, while it is directly obtained from the phase shift at a fixed lag in the latter.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.401-406
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• 2017

Breast cancer rates are increasing every year, biopsy for diagnosing breast cancer is increasing as well. Biopsy also invasive test, have bad side effects from patients anxiety, infection, bleeding. In this study, Conduct a survey of 69 patients who brest lesion patient, both B-mode ultrasound and elastography exam and B-mode ultrasound was classified according to the BI-RADS category, and the elastography exam was classified according to the Color overlay pattern that the value of the kPa expressed in relation to the propagation velocity of Transverse waves. The optimal cut off value of the highest sensitivity and specificity was 54.70 kPa. In the color overlay pattern, Dark Blue 42 people, Light blue ~ Red 27 people classified results and BI-RADS classification results, benign 40 people and malignant 29 people classified results showed similar results. Therefore, It is judged that the color overlay pattern is positive when classified into Dark Blue, and malignant when classified into Light blue ~ Red. In conclusion, breast elastography is expected to play a innovative role in reducing the number of breast cancer examinations and classify between benign and malignant tumor.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.4
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• pp.457-463
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• 2014

Ultrasound measurements of backfat thickness (UBF), longissimus muscle area (ULMA) and marbling score (UMS) and carcass measurements of carcass weight (CW), backfat thickness (BF), longissimus muscle area (LMA), and marbling score (MS) on 7,044 Hanwoo steers were analyzed to estimate genetic parameters. Data from Hanwoo steers that were raised, finished in Hoengseong-gun, Gangwon-do (province) and shipped to slaughter houses during the period from October 2010 to April 2013 were evaluated. Ultrasound measurements were taken at approximately three months before slaughter by an experienced operator using a B-mode real-time ultrasound device (HS-2000, FHK Co. Ltd., Tokyo, Japan) with a 3.5 MHz linear probe. Ultrasound scanning was on the left side between 13th rib and the first lumbar vertebrae. All slaughtering processes and carcass evaluations were performed in accordance with the guidelines of beef grading system of Korea. To estimate genetic parameters, multiple trait animal models were applied. Fixed effects included in the models were: the effects of farm, contemporary group effects (year-season at the time of ultrasound scanning in the models for UBF, ULMA, and UMS, and year-season at slaughter in the models for CW, BF, LMA, and MS), the effects of ultrasound technicians as class variables and the effects of the age in days at ultrasound scanning or at slaughtering as linear covariates, respectively for ultrasound and carcass measures. Heritability estimates obtained from our analyses were 0.37 for UBF, 0.13 for ULMA, 0.27 for UMS, 0.44 for CW, 0.33 for BF, 0.36 for LMA and 0.54 MS, respectively. Genetic correlations were strongly positive between corresponding traits of ultrasound and carcass measures. Genetic correlation coefficient between UBF and BF estimate was 0.938, between ULMA and LMA was 0.767 and between UMS and MS was 0.925. These results suggest that ultrasound measurement traits are genetically similar to carcass measurement traits.

• Journal of Biomedical Engineering Research
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• v.23 no.6
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• pp.419-430
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• 2002

In this paper. we propose an efficient method for implementing hi-directional pixel-based focusing(BiPBF) based on a sparse array imaging technique. The proposed method can improve spatial resolution and frame rate of ultrasound imaging with reduced hardware complexity by synthesizing transmit apertures with a small number of sparsely distributed subapertures. As the distance between adjacent subapertures increases, however. the image resolution tends to decrease due to the elevation of grating lobes. Such grating lobes can be eliminated in conventional synthetic aperture imaging techniques. On the contrary, grating lobes arisen from employing sparse synthetic transmit apertures can not be eliminated, which has been shown analytically in this paper. We also propose the condition and method for suppressing the grating lobes below -40dB, which is generally required in practical imaging. by placing the transmit focal depth at a near depth and properly selecting the subaperture distance in Proportion to receive aperture size. The results of both the Phantom and in vivo experiments show that the proposed method implements two-wav dynamic focusing using a smaller number of subapertures, resulting in reduced system complexity and increased frame rate.

• Journal of Biomedical Engineering Research
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• v.29 no.2
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• pp.122-131
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• 2008

For B-mode ultrasound images, we propose an image enhancement algorithm based on a multi-resolution approach, which consists of edge enhancing and noise reducing procedures. Edge enhancement processing is applied sequentially to coarse-to-fine resolution images obtained from wavelet-transformed data. In each resolution, the structural features of each pixel are examined through eigen analysis. Then, if a pixel belongs to an edge region, we perform two-step filtering: that is, directional smoothing is conducted along the tangential direction of the edge to improve continuity and directional sharpening is conducted along the normal direction to enhance the contrast. In addition, speckle noise is alleviated by proper attenuation of the wavelet coefficients of the homogeneous regions at each band. This region-based speckle-reduction scheme is differentiated from other methods that are based on the magnitude statistics of the wavelet coefficients. The proposed algorithm enhances edges regardless of changes in the resolution of an image, and the algorithm efficiently reduces speckle noise without affecting the sharpness of the edge. Hence, compared with existing algorithms, the proposed algorithm considerably improves the subjective image quality without providing any noticeable artifacts.

• International Journal of Vascular Biomedical Engineering
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• v.3 no.1
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• pp.6-13
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• 2005

Individual clinical significance of each layer of CCA (common carotid artery) has not been well studied. We intended to measure the intima thickness (IT), media thickness (MT), and intima-media thickness (IMT) of CCA separately and tried to analyze the clinical significance. One hundred fifty one consecutive patients (mean age: $57{\pm}15$ years; 77 males, 74 females) underwent CCA scanning using high-resolution ultrasound. The images were off-line analyzed using B-mode ultrasound image processing, devised for individual measurement of IT and MT as well as IMT. The mean coefficients of variation of new method measuring IT, MT, and IMT separately were 0.16% for IMT and 0.21% for both IT and MT. The IT (p < 0.01), MT (p < 0.01) as well as IMT (p < 0.001) of patients with atherosclerotic disease were significantly thicker than that of the patients without atherosclerotic disease. Patients with hypertension showed significantly thicker IT (p < 0.01), MT (p < 0.001), and IMT (p < 0.001) than that of the patients without hypertension. However, only IT was thicker in patients with smoking (p<0.01) than that of the patients without smoking.

• Journal of Biomedical Engineering Research
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• v.27 no.3
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• pp.117-124
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• 2006

Recently, active research has been going on to measure the elastic modulus of human soft tissue with medical ultrasound imaging systems for the purpose of diagnosing cancers or tumors which have been difficult to detect with conventional B-mode imaging techniques. In this paper, a real-time ultrasonic elasticity imaging system is implemented in software on a Pentium processor-based ultrasonic diagnostic imaging system. Soft tissue is subjected to external vibration, and the resulting tissue displacements change the phase of received echoes, which is in turn used to estimate tissue elasticity. It was confirmed from experiment with a phantom that the implemented elasticity imaging system could differentiate between soft and hard regions, where the latter is twice harder than the former, while operating at an adequate frame rate of 20 frames/s.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1047-1056
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• 2007

Basically, an ultrasonic imaging system has two fundamental imaging modes available. One is the B-mode imaging modality which provides an image of reflection coefficient, and the other is the Doppler color flow mode that maps blood flow inside the human heart and blood vessels. This paper presents a new method of detecting and compensating for aliasing that occurs when the Doppler frequency exceeds one-half of the pulse-repetition frequency (PRF). Its validity is shown by computer simulation. The new method not only extends the measurable Doppler frequency, but also helps to reduce the effect of noise. The results show that the aliasing can be compensated for correctly fur signal-to-noise ratios down to 20 dB.