• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1994년도 추계학술대회
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• pp.153-156
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• 1994

An in vitro steady flow experiment was performed in order to test the accuracy of velocity measurement obtained through a pulsed Doppler echocardiography. A flow phantom was designed for the use in a wide velocity range at a given flow rate. The results showed that the pulsed Doppler velocity measurement obtained in this flow phantom is accurate at low flow rates. However, ultrasound velocity measurement should be performed under a careful considerations of PRF and Doppler gain settings, especially at higher flow rates.

• Restorative Dentistry and Endodontics
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• 제39권1호
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• pp.68-73
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• 2014

When a tooth shows discoloration and does not respond to the cold test or electric pulp test (EPT) after a traumatic injury, its diagnosis can be even more difficult due to the lack of proper diagnostic methods to evaluate its vitality. In these case reports, we hope to demonstrate that ultrasound Doppler might be successfully used to evaluate the vitality of the tooth after trauma, and help reduce unnecessary endodontic treatments. In all three of the present cases, the teeth were discolored after traumatic injuries and showed negative responses to the cold test and EPT. However, they showed distinctive vital reactions in the ultrasound Doppler test during the whole observation period. In the first case, the tooth color returned to normal, and the tooth showed a positive response to the cold test and EPT at 10 wk after the injury. In the second case, the tooth color had returned to its normal shade at 10 wk after the traumatic injury but remained insensitive to the cold test and EPT. In the third case, the discoloration was successfully treated with vital tooth bleaching.

• International Journal of Vascular Biomedical Engineering
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• 제1권1호
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• pp.3-12
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• 2003

Ultrasonic pulsed Doppler velocimetry has become a standard international method of classifying carotid disease. Because the measured angle adjusted velocity increases as the Doppler angle increases, examinations should be performed at a convenient standard Doppler examination angle. An angle of 60 degrees is achievable throughout most examinations. Multiple Doppler viewing angles allow the acquisition of velocity vectors during the cardiac cycle, revealing the complex velocity patterns. Ultrasonic velocimetry (whether Doppler or time domain) is based on changes in the phase of the ultrasound echo. Other examinations can be done based on the echo phase. Slow motions of organs such as the brain can be used to monitor changes in edema. Measurements of tissue strain due to the pulsatile filling of the arterioles. This plethysmographic imaging method can display differences in tissue perfusion because of different tissue types and changes in autonomic activity.

• The Korean Journal of Pain
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• 제34권3호
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• pp.339-345
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• 2021

Background: Ultrasound-guided caudal epidural injection (CEI) is limited in that it cannot confirm drug distribution at the target site without fluoroscopy. We hypothesized that visualization of solution flow through the inter-laminar space of the lumbosacral spine using color Doppler ultrasound alone would allow for confirmation of drug distribution. Therefore, we aimed to prospectively evaluate the usefulness of this method by comparing the color Doppler image in the paramedian sagittal oblique view of the lumbosacral spine (LS-PSOV) with the distribution of the contrast medium observed during fluoroscopy. Methods: Sixty-five patients received a 10-mL CEI of solution containing contrast medium under ultrasound guidance. During injection, flow was observed in the LSPSOV using color Doppler ultrasonography, following which it was confirmed using fluoroscopy. The presence of contrast image at L5-S1 on fluoroscopy was defined as "successful CEI." We then calculated prediction accuracy for successful CEI using color Doppler ultrasonography in the LS-PSOV. We also investigated the correlation between the distribution levels measured via color Doppler and fluoroscopy. Results: Prediction accuracy with color Doppler ultrasonography was 96.9%. The sensitivity, specificity, positive predictive value, and negative predictive value were 96.7%, 100%, 100%, and 60.0%, respectively. In 52 of 65 patients (80%), the highest level at which contrast image was observed was the same for both color Doppler ultrasonography and fluoroscopy. Conclusions: Our findings demonstrate that color Doppler ultrasonography in the LS-PSOV is a new method for determining whether a drug solution reaches the lumbosacral region (i.e., the main target level) without the need for fluoroscopy.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2261-2266
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• 2011

초음파 컬러 유동 사상에서 가장 많이 사용되는 Kasai 알고리듬은 래그-1 자기상관 방법으로서 적은 계산량으로 비교적 우수하게 도플러 평균주파수를 추정한다. 하지만 특히 깊은 곳을 영상화하는 경우 낮은 신호 대 잡음비로 인해 추정성능이 저하된다. 본 논문에서는 낮은 신호 대 잡음비에서도 Kasai 알고리듬보다 우수한 디에일리어스된 래그-2 자기상관방법을 제안하고 시뮬레이션을 통해 성능을 검증하였다. 제안한 방법은 잡음이 존재하는 경우 도플러 평균주파수 추정 성능을 평균 자승 오차 측면에서 전반적으로 약 2~3dB 정도 개선시켜줌을 확인하였다.

• 한국방사선학회논문지
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• 제17권7호
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• pp.1049-1055
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• 2023

칼라도플러 초음파에서 요로결석의 종류에 따라 트윈클링 허상의 발생정도에 차이가 있는지 알아보고자 하였다. 색이 다른 두 종류의 요로결석에 대하여 물탱크에서 트윈클링 허상의 발생정도를 비교하고 결석의 표면과 성분을 분석하였다. 결석의 표면상태는 갈색의 결석에서 과립형 요철이 두드러져 보였다. 트윈클링 허상은 흰색의 결석에서 음향음영의 일부를 차지하는 1등급이 갈색의 결석에서 음향음영의 전체를 차지하는 2등급이 나타났다. 결석의 성분은 탄소와 산소를 제외한 칼슘과 인의 함유량이 가장 높게 나타났다. 결석성분 중 인의 함유량이 높을수록 결석표면이 매끄러우며 트윈클링 허상이 짧게 나타났다. 초음파검사로서 결석의 성분을 예측하기 위한 단편적인 역할을 기대할 수 있을 것이며 이는 결과적으로 치료계획에 도움이 된다.

• Journal of Acupuncture Research
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• 제26권2호
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• pp.49-58
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• 2009

Objectives : The aim of this study was to investigate whether Doppler ultrasound device is applicable for the evaluation of facial palsy patients. Methods : A total of 25 patients participated in the first assessment and 22 of them finished a follow-up assessment one week later. An assessment comprised of a Minimax-Doppler-K device examination on bilateral acupoints $ST_5$, $SI_{19}$, $ST_2$, and $BL_1$, House-Brackmann grading, and subjective symptom questionnaire. Measurement reliability was assessed and clinically meaningful variations of Doppler measurement values were explored. Results : Doppler ultrasound examination revealed a significant difference of some measurement values between values of the symptom side and the contralateral side, between groups of severe paralysis and moderate paralysis, and between groups of short duration(0-3 weeks) and long duration (3 weeks-5 months) by non-parametric analyses (p<0.05). Several re-examination values showed a significant correlation with the first examination values by Spearman's correlation tests (p<0.05). Conclusions : This study revealed several possibilities for the clinical application of this device. Further validity tests and device improvements for a user's convenience would be helpful for its practical application.

• 대한의용생체공학회:의공학회지
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• 제20권3호
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• pp.275-281
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• 1999

현재 널리 쓰이고 있는 PW 도플러 시스템 주파수가 나이퀴스트 주파수를 초과할 경우 스텍트럼 aliasing 현상에 의하여 정확한 혈류 속도의 측정을 할 수 없다는 문제점을 가지고 있다 . 도플러 스펙트럼의 aliasing 현상을 극복하기 위하여 통상적으로 기준선 (Base Line) 이동기법을 사용하고 있으나 도플러 오디오 신호는 aliasing 된채로 남게 된다. 이 논문에서는 주파수 천이 및 필터링 기법들을 적절히 적용하여 기준선 이동시 도플러 스텍트럼과 오디오 신호의 aliasing 현상을 함께 제거할 수 있는 기법을 제안한다. 제안된 방법은 단방향 혈류 성분을 검사하는 경우 aliasing 현상 없이 측정 가능한 도플러 주파수를 나이퀴스트 주파수의 두배인 PRF 까지 증가되도록 한다. 실제 시스템에서 얻어진 신호를 이용하여 제안된 방법을 실험적으로 검증하였다.

• The Journal of the Acoustical Society of Korea
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• 제29권1E호
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• pp.11-27
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• 2010

Nowadays, ultrasound Doppler imaging is widely used in assessing cardiovascular functions in the human body. However, a major drawback of ultrasonic Doppler methods is that they can provide information on blood flow velocity along the ultrasound beam propagation direction only. Thus, the blood flow velocity is estimated differently depending on the angle between the ultrasound beam and the flow direction. In order to overcome this limitation, there have been many researches devoted to estimating both axial and lateral velocities. The purpose of this article is to survey various two-dimensional velocity estimation methods in the context of Doppler imaging. Some velocity vector estimation methods can also be applied to determine tissue motion as required in elastography. The discussion is mainly concerned with the case of estimating a two-dimensional in-plane velocity vector involving the axial and lateral directions.

• The Journal of the Acoustical Society of Korea
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• 제29권3E호
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• pp.107-110
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• 2010

In this paper, the rationale and contents of the special issue of the Journal of the Acoustical Society of Korea regarding comprehensive reviews on past, present and future of biomedical ultrasound are described. Brief descriptions of invited articles are given, and efforts by all contributing authors are gratefully acknowledged.