• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1887-1893
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• 2016

The VSA(Video Signal Analysis) method is the time-domain approach for estimating ultrasonic attenuation which utilizes the envelop signals from backscattered rf signals. The echogenicity of backscattered ultrasonic signals, however, from deeper depths are distorted when the broadband transmit pulse is used and it degrades the estimation accuracy of attenuation coefficients. We propose the modified VSA method using adaptive bandpass filters according to the centroid shift of echo signals as a pulse propagates. The technique of dual-reference diffraction compensation is also proposed to minimize the estimation errors because the difference of attenuation properties between the reference and sample aggravates the estimation accuracy when the differences are accumulated in deeper depth. The proposed techniques minimize the distortion of relative echogenicity and maximize the signal-to-noise ratio at the given depth. Simulation results for numerical tissue-mimicking phantoms show that the Rectangular-shaped filter with the appropriate center frequency exhibits the best estimation performance and the technique of the dual-reference diffraction compensation dramatically improves accuracy for the region after the beam focus.

• Parasites, Hosts and Diseases
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• v.37 no.2
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• pp.77-83
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• 1999

To ascertain residual sonographic and histopathological findings of clonorchiasis after treatment, the present study evaluated sonographic findings in rabbits which were infected with 500 metacercariae of C.sinensis every 6 months for 18 months after treatment with praziquantel. The sonographic findings were analyzed in terms of intrahepatic bile duct dilatation and periductal echogenicity, and histopathological findings were observed after the last sonographic examination. Compared with the sonographic findings before treatment, dilatation of the intrahepatic bile ducts became mild to some degree in four of the seven cases and increased periductal echogenicity resolved in four of them. The histopathological specimens after 18 months showed that periductal inflammation has almost resolved but moderate dilatation of the intrahepatic ducts and mucosal hyperplasia persisted. The periductal fibrosis minimally resolved. The log-lasting sonographic findings in cured clonorchiasis make sonography less specific.

• Journal of Veterinary Clinics
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• v.22 no.3
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• pp.186-189
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• 2005

For the assessment of the clinical application of histogram on internal parenchymal organs, ultrasonography with a multi-frequency transducer was taken. We scanned in the region of right cranial abdomen for both liver and right kidney, and left cranial abdomen for liver, spleen and left kidney in 9 normal Beagle dogs. The data from histogram examined in a region of interest centered on each picture element of B-mode images at the same depth were compared among liver, renal cortex, spleen, cortex and medulla of each kidney. The right renal cortex showed significantly lower echogenicity than parenchyma of liver by $15{\%}$. Spleen was more echogenic than the cortex of the left kidney by $23{\%}$, and liver was more echogenic than the left renal cortex by $30{\%}$. Renal cortex was more echogenic than medulla by $47{\%}$ and $65{\%}$ on the right and left side, respectively (p<0.05). The mean (${\pm}SD$) values calculated echogenicity were $46.2{\pm}12.3\;(95\%$ confidential interval (CI), 41.0 to 55.0) and $53.4{\pm}12.1\;(95\%$ CI, 47.0 to 55.1) in in the right renal cortex and liver parenchyma, $65.0{\pm}11.8\;(95\%$ CI, 57.9 to 71.0) and $51.0{\pm}16.9\;(95\%$ CI, 42.8 to 54.1) in splenic parenchyma and renal cortex. And the mean values calculated echogenicity were $65.0{\pm}10.15\;(95\%$ CI, 60.1 to 71.5) and $52.0{\pm}9.4\;(95\$ CI, 43.8 to 60.3) in liver parenchyma and the left renal cortex, $54.5{\pm}18.3\;(95\%$ CI, 40.1 to 62.8) and $35.0{\pm}16.2\;(95\%$ CI, 24.2 to 43.6) in the left renal cortex and medulla. And the mean values calculated echogenicity were $55.0{\pm}14.4\;(95\%$ CI, 47.3 to 61.7) and $40.0{\pm}13.2\;(95\%$ CI, 34.3 to 46.7) in the right renal cortex and medulla, respectively. In addition, the echogenicity ratios were $0.86{\pm}0.11$ between the right renal cortex and liver parenchyma, $1.37{\pm}0.47$ between spleenic parenchyma and the left renal cortex, $1.30{\pm}0.19$ between liver parenchyma and the left renal cortex. All the values measured showed significant different (p<0.05). Ultrasound histogram is simple, useful and feasible to evaluate the sonographic architecture of the internal organs such as liver, spleen and kidney, quantitatively.

• Korean Journal of Veterinary Research
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• v.38 no.4
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• pp.918-928
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• 1998

The present study was done with two aims. First, to evaluate the radiographic measurements of liver volumes in normal and hepatomegaly dogs induced by carbon tetrachloride. Second, to investigate quantitative tissue echo pattern by ultrasonography. Gray level histogram of the normal liver and the kidney were estimated with carbon tetra-chloride intoxication. In normal, r-square for liver volume to body weight was 0.93372, and this showed direct linear regression. Gray level histograms of the normal liver and the kidney were $19.150{\pm}2.490$(mean${\pm}$SD) and $13.175{\pm}2.686$(mean${\pm}$SD) respectively(p < 0.01). Liver parenchymal echogenicity was more hyperechogenic than kidney cortex echogenicity. Liver/Kidney ratio was $1.504{\pm}0.313$ and it can be used relative comparison of liver and kidney parenchymal echogenicity. In carbon-tetrachloride($CCl_4$) intoxication, changes of liver volume appeared to increase up to 24 hours after administration (p < 0.05), and decreased gradually to normal level after 2~5 days. Gray level histogram of liver parenchyma decreased up to 24hours (p < 0.01) after intoxication and then gradually increased to normal level. But that of kidney cortex had no significant change. Liver/Kidney ratio also decreased by 2 days(p < 0.01) and then gradually increased to normal level. On histopathologic features of hepatic tissues in carbon tetrachloride intoxication, both coagulative necrosis of hepatic cell and hemorrhage of centrilobular & midzonal area were identified. Conclusively, plain radiography is a useful diagnostic method for evaluating liver volume in mild hepatomegaly. Especially, it is considered that an adequate numerical processing of the liver length, depth and thoracic width and depth measurement would be helpful. Using gray level histogram, ultrasonographic evaluation was useful objective methods in early diagnosis of diffuse hepatic disease.

• Journal of Veterinary Clinics
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• v.18 no.2
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• pp.139-145
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• 2001

This study was undertaken to determine the normal serial ultrasonographic appearance of the postpartum uterine involution in small pet dogs (Yorkshire terrier and Maltese). Postpartum changes in uterine shape, architecture, echogenicity and diameter were monitored by ultrasonography in 12 small pet dogs. Serial ultrasonographic examinations were done daily during the first week, 3 days interval from 8 to 30 days, and weekly from 31 to 100 days postpartum. The excretory period of vaginal discharge in 12 normal bitches of uterine involution was finished completely within 3 weeks postpartum. The short axis shape of the uterus was initially often flaccid-appearing. It varied from circular to polygonal. This lasted until 15.75$\pm$3.84 days postpartum, during which time the short axis uterine shape gradually changed to circular. Also, the long axis shape of the uterus was a beaded appearance until 30.89$\pm$4.25 days postpartum. After 30 days, it was appeared as tubular shape between placental and interplacental sites. The ultrasonographic image of the postpartum uterus consisted of four echogenicity distinct layers. Uterine wall was represented as very hyperechoic serosa, hypoechoic myometrium, hyperechoic endometrium and anechoic structures of fluid in the uterine cavity until 7 days postpartum. The individual uterine layers were most prominent during the first week postpartum, and they became progressively less distinct throughout the course of uterine involution. The thickness of myometrium was decreased rapidly in the placental sites from 4.47$\pm$1.42 mm at 1 day to 1.92$\pm$0.26 mm at 16 day, and in the interplacental sites from 3.19$\pm$0.61 mm at 1 day to 1.39$\pm$0.61 mm at 16 day. And it was decreased slowly until 94 day and was been minimum thickness at 94 day. The thickness of endometrium was also decreased like that of myometrium. The uterine diameter in the placental sites was decreased from 22.28$\pm$3.01 mm at 1 day to 16.11$\pm$1.46 mm at 7 day, and in the interplacental sites was decreased from 13.65$\pm$2.34 mm at 1 day to 9.41$\pm$1.59 mm at 7 day postpartum. From 7 day to 93 day, the change of diameter was more and more slow. At 94 days postpartum, the uterine diameter was 5~6 mm both placental and interplacental sites, and the uterine horns were uniform hypoechoic, tubular structures without enlargement. Therefore, complete involution of the uterus occurred at 94 days. It was concluded that normal post partum uterine involution in small pet dogs appeared to be completed 94 days postpartum by gross findings such as vaginal discharges, and by ultrasonographic findings, uterine shape and echogenicity.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.5
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• pp.43-51
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• 2010

Attenuation coefficients of medical ultrasound not only reflect the pathological information of tissues scanned but also provide the quantitative information to compensate the decay of backscattered signals for other medical ultrasound parameters. Based on the frequency-selective attenuation property of human tissues, attenuation estimation methods in spectral domain have difficulties for real-time implementation due to the complexicity while estimation methods in time domain do not achieve the compensation for the diffraction effect effectively. In this paper, we propose the modified VSA method, which compensates the diffraction with reference phantom in time domain, using adaptive bandpass filters with decreasing center frequencies along depths. The adaptive bandpass filtering technique minimizes the distortion of relative echogenicity of wideband transmit pulses and maximizes the signal-to-noise ratio due to the random scattering, especially at deeper depths. Since the filtering center frequencies change according to the accumulated attenuation, the proposed algorithm improves estimation accuracy and precision comparing to the fixed filtering method. Computer simulation and experimental results using tissue-mimicking phantoms demonstrate that the distortion of relative echogenicity is decreased at deeper depths, and the accuracy of attenuation estimation is improved by 5.1% and the standard deviation is decreased by 46.9% for the entire scan depth.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.494-501
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• 2012

In the present paper, the ultrasound blood images were measured at both the human radial artery(RA) and common carotid artery(CCA), depending on the age, and the pulsatility index of blood echogenicity(PIBE) was analyzed. In addition, the ultrasound blood images were measured at both RA and CCA of both the stroke patients and the control group, and PIBE was compared. PIBE of RA for the young group was similar with that for the old group ($0.13{\pm}0.11$ and $0.16{\pm}0.03$). PIBE of CCA for the young group, however, was larger than that for the old group ($0.70{\pm}0.21$ and $0.32{\pm}0.01$), and was more variable depending on the subject. Similarly, the fibrinogen concentrations of the patients ($336{\pm}61$ and $340{\pm}126mg/dl$) were more than that of the control group ($264{\pm}38$ and $257{\pm}43mg/dl$), for both RA and CCA. The results indicate the possibility of the ultrasonic test on the correlation between erythrocyte aggregation and stroke, and it is expected that the in-vivo EA measurement would be clinically useful.

• Journal of the Korean Society of Radiology
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• v.82 no.2
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• pp.382-392
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• 2021

Purpose To evaluate the ultrasonographic characteristics of steatocystomas focusing on the features that aid in differentiating them from epidermal inclusion cysts and lipomas. Materials and Methods The ultrasonographic findings of 14 histologically proven steatocystomas in 10 patients were retrospectively reviewed. The following features were assessed: the layer of involvement, shape, margin, echogenicity, posterior acoustic features, and the presence of a visible wall or intralesional striations. The findings were compared with those of subcutaneous lipomas and epidermal inclusion cysts to identify those findings that aid in the differential diagnosis of steatocystomas. Results The majority of steatocystomas appeared as a subcutaneous mass (n = 6, 42.9%) or a mass involving both the dermal and subcutaneous layers (n = 6, 42.9%). Steatocystomas exhibited a well-defined smooth margin (n = 12, 85.7%) and homogeneous echogenicity (n = 9, 64.3%), and showed no specific posterior acoustic features (n = 9, 64.3%). The most important features that differentiated steatocystomas from epidermal inclusion cysts were a homogeneous internal echotexture (p = 0.009) and absent or less prominent posterior acoustic enhancement (p < 0.001). The features that distinguished steatocystomas from lipomas were the margin (p < 0.001), echogenicity (p = 0.034), internal echotexture (p = 0.004), and the absence of intralesional striations (p < 0.001). Conclusion Steatocystomas appeared as well-defined homogeneous masses with mild or absent posterior acoustic enhancement.

• Parasites, Hosts and Diseases
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• v.33 no.2
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• pp.117-124
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• 1995

This study was performed to evaluate diagnostic sensitivity and specificity of sonography on clonorchiasis. During the 9 months from March to November 1994, sonography skin test, stool examination, and medical examination were performed to 609 volunteers of Pohang which is located along the Hyongsan-gang (Rivers and is one of well-known endemic areas of clonorchiasis. The sensitivity of sonography was either 21% if the intrahepatic ducts dilatation was assumed to be the only positive anding or 52% if the periductal echogenicity was also included as one of positive findings. The sensitivity of skin test was 62%. The sensitivity was 46% if the diagnostic criteria were arbitrarily assumed as being positive in skin test and having either sonographic findings. The sonographic finding of fusiform, non-shadowing, weakly echogenic foci in gallbladder or in billiaiy tree indicating the flukes or aggregates of flukes was not obvious in this study. The specificity of sonography was either 95% if the intrahepatic ducts dilatation was assumed to be the only positive finding or 82% if the periductal echogenicity was also included as one of positive findings. The specificity of skin test was 52%. The specificity was 90% if the diagnostic criteria was arbitrarily assumed as being positive in skin test and having either sonographic findings.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.22
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• pp.10039-10043
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• 2014

Background: In Pakistan thyroid cancer is responsible for 1.2% cases of all malignant tumors. Ultrasonography (US) is helpful in detecting cancerous thyroid nodules on basis of different features like echogenicity, margins, microcalcifications, size, shape and abnormal neck lymph nodes. We therefore aimed to calculate diagnostic accuracy of ultrasound in detection of carcinoma in thyroid nodules taking fine needle aspiration cytology as the reference standard. Materials and Methods: A cross-sectional analytical study was designed to prospectively collect data from December 2010 till December 2012 from the Department of Radiology in Aga Khan University Hospital, Karachi, Pakistan. A total of 100 patients of both genders were enrolled after informed consent via applying non-probability consecutive sampling technique. Patients referred to Radiology department of Aga Khan University to perform thyroid ultrasound followed by fine-needle aspiration cytology of thyroid nodules were included. They were excluded if proven for thyroid malignancy or if their US or FNAC was conducted outside our institution. Results: The subjects comprised 76 (76%) females and 24 males. Mean age was $41.8{\pm}SD$ 12.3 years. Sensitivity and specificity with 95%CI of ultrasound in differentiating malignant thyroid nodule from benign thyroid nodule calculated to be 91.7% (95%CI, 0.72-0.98) and 78.94% (0.68-0.87) respectively. Reported positive predictive value and negative PV were 57.9% (0.41-0.73) and 96.8% (0.88-0.99) and overall accuracy was 82%. Likelihood ratio (LR) positive was computed to be 4.3 and LR negative was 0.1. Conclusions: Ultrasonography has a high diagnostic accuracy in detecting malignancy in thyroid nodules on the basis of features like echogenicity, margins, micro calcifications and shape.