• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1994년도 춘계학술대회
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• pp.96-99
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• 1994

Despite the simplicity of processing, a conventional autocorrelation function(ACF) method for the precise determination of fetal heart rate (FHR) has many problems. In case of weak or noise corrupted Doppler ultrasound signal. the ACF method is very sensitive to the threshold level and data window length. It is very troublesome to extract FHR when there is a data loss. To overcome these problems, the high resolution pitch detection algorithm was adopted to estimate the FHR. This method is more accurate, robust and reliable than the ACF method. With a lot of calculation, however, it is impossible to process real time FHR estimation. This paper is presented a new FHR estimation algorithm for real time processing.

• Journal of Chest Surgery
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• 제51권3호
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• pp.213-215
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• 2018

Aneurysm and pseudoaneurysm of the dorsalis pedis artery (DPA) are rare vascular entities. Pseudoaneurysms of the DPA are commonly due to blunt trauma, sharp penetrating injury, fracture, or iatrogenic injury. Herein, we report the case of a patient with a rare iatrogenic pseudoaneurysm that occurred after blood sampling. The diagnosis was suspected based on palpitation of a pulsatile mass on the dorsal foot and confirmed by color Doppler ultrasound and computed tomography angiography. Surgical treatment was successfully performed by reconstruction with an autologous venous graft. The patient recovered well, with no ischemic complications.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1991년도 추계학술대회
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• pp.79-82
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• 1991

Digital FHR monitoring system based on the personal computer combined wi th the digital signal processing (DSP) board was implemented. The DSP board acquires and digitally processes ultrasound fetal Doppler signal for digital rectification, envelope detection, autocorrealtion function calculation and its peak position detection. The personal computer interfaced with the DSP board is in charge of graphic display, hardcopy, data taransmission and on-line analysis of fetal heart rate change including on-line warning system, base-line estmation, acceleration, deceleration and variability. The advantages of PC-DSP based system can be summarized as follows: 1) Minimum hardware realization. 2) Increased flexibility. 3) Total care system.

• 대한의용생체공학회:의공학회지
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• 제12권3호
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• pp.209-214
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• 1991

Digital fetal monitoring system based on the personal computer combined with the digital signal processing (DSP) board was implemented. The DSP board acquires and digitally processes ultra- sound fetal Doppler signal for digital signal conditioning, rectification, low -pass filtering, autocorrealtion function calculation and its peak detection. The personal computer interfaced with the DSP board is in charge of graphic display, hardcopy, data transmission and on -line analysis of fetal heart rate change including on - line warning system, base -line estmation, acceleration, deceleration and variability. It is one of the most suitable situation to apply the DSP chip for siganl conditioning, digital filtering of ultrasound fetal Dopier signal and fetal heart rate estimation using autocorrelation technique .

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1993년도 춘계학술대회
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• pp.81-85
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• 1993

Despite the simplicity of processing, conventional autocorrelation function (ACF) method for the precise determination of fetal heart rate (FHR) has many problems. In the case of weak or noise corrupted Doppler ultrasound singnals, the ACF method is very sensitive to the threshold level and data window length. It is real troublesome to extract FHR when there is a data loss. To overcome these problems, the high resolution pitch detection algorithm is adapted to estimate the FHR. The FHR is determined from the correlation of two interconnected segments by its maximum correlation value. FHR is compensated with a constant correlation threshold in a greatly smeared noise signal. This method yields more accurate, robust and reliable than the ACF method.

• Journal of Yeungnam Medical Science
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• 제8권1호
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• pp.63-71
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• 1991

저자들은 1990년 5월 1일부터 1991년 4월 30일까지 영남대학교 의과대학 부속병원 산부인과에 정기검진을 위해 내원한 157명의 정상 임산부를 대상으로 제대동맥에서 시행한 도플러초음파 160회의 검사 결과를 엄신 주수에 따라 분석하여 다음과 같은 결과를 얻었다. 제대동맥의 최고 수축기 혈류속도는 임신이 진행함에 따라 증가 양상을 보임으로써 임신이 증가함에 따라 제대 동맥 혈류량은 증가함을 관찰할 수 있었다. 임신이 진행함에 따라 제대태반 순환계 말초 저항이 점차적으로 감소함으로 인해 제대동액 이완기말 혈류속도도 중가 양상을 보였다. S/D ratio는 최고 수축기 혈류속도의 증가에도 불구하고 이완기말 혈류속도의 점차적인 증가로 인하여 임신이 진행함에 따라 오히려 감소함을 관찰할 수 있었다. 임신이 지속함에 따라 PI, RI도 감소하는 양상을 보였다.

• Korean Journal of Radiology
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• 제20권5호
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• pp.759-772
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• 2019

Objective: To investigate the value of ultrasound (US) microflow assessment in distinguishing malignant from benign solid breast masses as well as the association between US parameters and histologic microvessel density (MVD). Materials and Methods: Ninety-eight breast masses (57 benign and 41 malignant) were examined using Superb Microvascular Imaging (SMI) and contrast-enhanced US (CEUS) before biopsy. Two radiologists evaluated the quantitative and qualitative vascular parameters on SMI (vascular index, morphology, distribution, and penetration) and CEUS (time-intensity curve analysis and enhancement characteristics). US parameters were compared between benign and malignant masses and the diagnostic performance was compared between SMI and CEUS. Subgroup analysis was performed according to lesion size. The effect of vascular parameters on downgrading Breast Imaging Reporting and Data System (BI-RADS) category 4A masses was evaluated. The association between histologic MVD and US parameters was analyzed. Results: Malignant masses were associated with a higher vascular index (15.1 ± 7.3 vs. 5.9 ± 5.6), complex vessel morphology (82.9% vs. 42.1%), central vascularity (95.1% vs. 59.6%), penetrating vessels (80.5% vs. 31.6%) on SMI (all, p < 0.001), as well as higher peak intensity (37.1 ± 25.7 vs. 17.0 ± 15.8, p < 0.001), slope (10.6 ± 11.2 vs. 3.9 ± 4.2, p = 0.001), area (1035.7 ± 726.9 vs. 458.2 ± 410.2, p < 0.001), hyperenhancement (95.1% vs. 70.2%, p = 0.005), centripetal enhancement (70.7% vs. 45.6%, p = 0.023), penetrating vessels (65.9% vs. 22.8%, p < 0.001), and perfusion defects (31.7% vs. 3.5%, p < 0.001) on CEUS (p ≤ 0.023). The areas under the receiver operating characteristic curve (AUCs) of SMI and CEUS were 0.853 and 0.841, respectively (p = 0.803). In 19 masses measuring < 10 mm, central vascularity on SMI was associated with malignancy (100% vs. 38.5%, p = 0.018). Considering all benign SMI parameters on the BI-RADS assessment, unnecessary biopsies could be avoided in 12 category 4A masses with improved AUCs (0.500 vs. 0.605, p < 0.001). US vascular parameters associated with malignancy showed higher MVD (p ≤ 0.016). MVD was higher in malignant masses than in benign masses, and malignant masses negative for estrogen receptor or positive for Ki67 had higher MVD (p < 0.05). Conclusion: US microflow assessment using SMI and CEUS is valuable in distinguishing malignant from benign solid breast masses, and US vascular parameters are associated with histologic MVD.

• Journal of Chest Surgery
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• 제48권5호
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• pp.328-334
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• 2015

Background: There have been a number of studies on mitral valve replacement and repeated percutaneous mitral balloon valvotomy for mitral valve restenosis after percutaneous mitral balloon valvotomy. However, studies on mitral valve repair for these patients are rare. In this study, we analyzed postoperative outcomes of mitral valve repair for mitral valve restenosis after percutaneous mitral balloon valvotomy. Methods: In this study, we assessed 15 patients (mean age, $47.7{\pm}9.7years$; 11 female and 4 male) who underwent mitral valve repair between August 2008 and March 2013 for symptomatic mitral valve restenosis after percutaneous mitral balloon valvotomy. The mean interval between the initial percutaneous mitral balloon valvotomy and the mitral valve repair was $13.5{\pm}7years$. The mean preoperative Wilkins score was $9.4{\pm}2.6$. Results: The mean mitral valve area obtained using planimetry increased from $1.16{\pm}0.16cm^2$ to $1.62{\pm}0.34cm^2$ (p=0.0001). The mean pressure half time obtained using Doppler ultrasound decreased from $202.4{\pm}58.6ms$ to $152{\pm}50.2ms$ (p=0.0001). The mean pressure gradient obtained using Doppler ultrasound decreased from $9.4{\pm}4.0mmHg$ to $5.8{\pm}1.5mmHg$ (p=0.0021). There were no early or late deaths. Thromboembolic events or infective endocarditis did not occur. Reoperations such as mitral valve repair or mitral valve replacement were not performed during the follow-up period ($39{\pm}16months$). The 5-year event-free survival was 56.16% (95% confidence interval, 47.467-64.866). Conclusion: On the basis of these results, we could not conclude that mitral valve repair could be an alternative for patients with mitral valve restenosis after percutaneous balloon mitral valvotomy. However, some patients presented with results similar to those of mitral valve replacement. Further studies including more patients with long-term follow-up are necessary to determine the possibility of this application of mitral valve repair.

• 대한한방내과학회지
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• 제25권3호
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• pp.418-426
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• 2004

Objectives : This study was designed to research whether transcranial doppler ultrasound(TCD) can yield a suitable diagnosis or prognosis for dizziness. Methods : To evaluate the blood flow, we measured the mean velocity(Vm), peak systolic velocity(Vs) and pulsatility index(PI) of the middle cerebral artery(MCA), vertebral artery(VA) and basilar artery(BA) in 54 dizziness patients and 44 normal subjects. To investigate the difference between dizziness patients and normal subjects, we selected 54 dizziness patients diagnosed normal by Brain MRI, and 44 normal subjects who did not have any symptoms of hyperlipemia, hypertension, diabetes melitus, heart disease, or smoking, diagnosed normal by Brain MRI. 30-69 year olds were divided into 30-49 year olds, 50-59 year olds and 60-69 year olds. Results : In normal subjects, there was a significantly higher Vm, Vs in the MCA and BA, and Vs in the VA of female subjects, and there was a significant difference in PI in the MCA and BA increasing with age. In comparison with normal subjects, dizziness patients had a significantly lower Vm in the BA. Male dizziness patients had significantly lower PI in the MCA. 30-49 year olds had significantly lower Vm in the BA. Conclusions : The significant difference in blood flow velocities in the BA between dizziness patients and normal subjects suggests that dizziness is related to blocking of blood flow in the BA and that diagnosis and prognosis can be made through TCD. More detailed study of dizziness patients will be needed.

• 대한한의진단학회지
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• 제14권2호
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• pp.85-100
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• 2010

Objectives: The purpose of this study was to evaluate diagnostic value of Transcranial Doppler Ultrasound about risk factor of stroke by comparing blood flow between patients with metabolic syndrome(MS group) and Normal group. Methods: 62 metabolic syndrome patients and 106 healthy adults were selected who had no cerebrovascular diseases, cardiovascular diseases and other systemic diseases. We measured the mean velocity(Vm), peak systolic velocity(Vs) and pulsatility index(PI) of MCA, ACA, PCA, VA, ICA in two groups using TCD. All subjects were divided by gender and age. Results: In comparing Ms group with normal group, Vm in the MCA, ACA, PCA, ICA and Vs in the MCA, ICA were lower in MS group. In all vessels, PI of MS group were higher than that of Normal group. In all vessels, Vm and Vs revealed negative correlation with age and PI revealed positive correlation with age. In 20-39 year olds, there was decrease in the Vs and Vm and increase of PI of MS group in comparison with normal group. There was significant difference in the Vm of PCA, ICA, Vs of MCA, PCA, ICA and PI of MCA, ACA. In 40-59 year olds, Vm in the MCA, ACA, ICA and Vs in the MCA, ACA were lower in MS group. PI in the MCA, ACA, PCA, ICA were higher in MS group. In 60-79 year olds, Vm of MCA, PCA, ICA was decreased in MS group than Normal group with no statistical signification. Vs in the MCA was lower and PI in the PCA was higher in MS group. In male, Vm of PCA and Vs of MCA were lower and PI of MCA, ACA, PCA, ICA were higher in MS group. In female, Vm of MCA, PCA, ICA and Vs of MCA, ICA were lower and PI of ACA, PCA, VA, ICA were higher in MS group. Conclusions: The significant difference in Vm, Vs, PI between MS group and normal group suggests hemodynamic disorder. Screening and prognosing high risk group can be done through TCD and this can be used to prevent stroke. More detailed study will be needed.