• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2007년도 하계종합학술대회 논문집
• /
• pp.357-358
• /
• 2007

Contrast enhancement in the field of ultrasound imaging contributes to improve the accuracy of medical diagnosis by enhancing the visibility of ultrasound images. This paper proposes a contrast enhancement method that improves the contrast of ultrasound images both globally and locally by fusing global and adaptive contrast enhancement methods. Experimental results show that our approach yields more competitive results than the existing global and adaptive contrast enhancement methods in enhancing the visibility of ultrasound images.

• 한국음향학회지
• /
• 제37권4호
• /
• pp.215-222
• /
• 2018

본 논문은 실시간 혈관내초음파 영상을 위한 후단부 시스템 개발과 성능 평가 결과에 관한 것이다. 개발한 후단부 시스템은 로직 사용량과 메모리 사용량을 최소화할 수 있는 효율적인 LUTs (Look-up Tables)을 사용하여 외부 메모리 없이 하나의 FPGA (Field Programmable Gate Array)만으로 시스템을 구성함으로써 시스템의 저비용, 소형화, 경량화가 가능하도록 설계하였다. 구현한 후단부 시스템의 정확도는 FPGA의 출력값과 VHDL (VHSIC Hardware Description Language) 코드를 MATLAB 프로그램을 사용하여 동일하게 구현하여 얻은 결과를 비교함으로써 검증하였다. 토끼 동맥을 이용한 ex-vivo 실험을 통하여 개발한 후단부 시스템이 실시간 혈관내초음파 영상에 적합함을 확인하였다.

• Physical Therapy Rehabilitation Science
• /
• 제9권4호
• /
• pp.287-294
• /
• 2020

Objective: This study aimed to investigate the effects of an ultrasound-based bar graph proportional to the quadriceps muscle thickness as a real-time visual feedback training tool in the elderly. Design: Cross-sectional study. Methods: Twenty-four elderly persons participated in this study and were randomly divided into three groups: oral training group (n=8, group 1), ultrasound imaging group (n=8, group 2), and graph group (n=8, group 3). In the pre condition, all participants performed maximal voluntary isometric contraction (MVIC) of the quadriceps with knee extension three times with oral training. In the post condition, group 1 performed MVIC of the quadriceps with oral training, group 2 performed MVIC of the quadriceps with real-time visual feedback using ultrasound imaging, and group 3 performed MVIC of the quadriceps with real-time visual feedback using a bar graph proportional to the quadriceps muscle thickness, three times for all groups. Muscle thickness, activity (mean, peak), tone, stiffness, logarithmic decrement, relaxation, and creep were measured in both conditions in all participants. Results: Visual feedback with a bar graph showed significant effects on muscle thickness, mean muscle activity, and peak muscle activity compared with oral training and visual feedback with ultrasound imaging (p<0.05). Conclusions: Isometric training of the quadriceps with real-time visual feedback using a bar graph proportional to the quadriceps muscle thickness may be more effective than other methods in improving muscle thickness and muscle activity. This study presented a tool that can help increase muscle thickness in the elderly.

• 한국음향학회지
• /
• 제42권3호
• /
• pp.203-213
• /
• 2023

의료용 초음파 영상 시스템에서, 영상점의 밖에서 오는 신호가 초음파 수신 집속 과정에서 완전히 제거되지 않으면 부엽을 발생시킨다. 부엽의 시간 신호가 영상점에서 오는 시간 신호(주엽)와 같이 중첩되어 나타나면 시간 영역에서 필터 처리를 이용하여 완전히 제거하기 어렵다. 그러나 수신 집속 과정에서 시간 -채널 신호를 푸리에 변환하면, 주엽과 부엽의 신호는 주파수 스펙트럼 영역에서 공간적으로 분리가 된다. 따라서 스펙트럼 영역에서 계산한 주엽과 부엽의 신호크기를 이용하여 크기 가중치를 계산하여 영상에 곱함으로써 부엽을 억제하였다. 그리고 주엽과 부엽의 스펙트럼이 인접할 때, 주엽과 부엽 스펙트럼 사이의 거리에 따라 거리 가중치를 적용하였다. 64 채널 선형 트랜스듀서를 사용하는 5 MHz의 초음파 영상 시스템에서 점확산 영상과 다른 밝기의 낭종을 가지는 스페클 영상을 합성하고 가중치를 적용하여 초음파 영상을 계산하였다. 점반사체 영상에서 해상도의 변화 없이 부엽이 크게 줄어들었으며 낭종 영상에서 대조도가 크게 개선됨을 컴퓨터 시뮬레이션으로 확인하였다.

• Journal of Medicine and Life Science
• /
• 제19권2호
• /
• pp.70-73
• /
• 2022

Here, we report a case of ultrasound-assisted subarachnoid block in a patient with severe kyphosis. A 69-year-old man was scheduled for metal removal from hip screws. He had a previous experience with subarachnoid block using the landmark-guided technique, but it was very difficult due to severe kyphosis. However, we could easily determine the correct needle insertion point using ultrasound imaging and performed a successful dural puncture on the first attempt. This case demonstrates the clinical usefulness of ultrasound imaging for subarachnoid blocks in patients with severe kyphosis.

• Korean Journal of Radiology
• /
• 제23권1호
• /
• pp.13-29
• /
• 2022

Nonalcoholic fatty liver disease, characterized by excessive accumulation of fat in the liver, is the most common chronic liver disease worldwide. The current standard for the detection of hepatic steatosis is liver biopsy; however, it is limited by invasiveness and sampling errors. Accordingly, MR spectroscopy and proton density fat fraction obtained with MRI have been accepted as non-invasive modalities for quantifying hepatic steatosis. Recently, various quantitative ultrasonography techniques have been developed and validated for the quantification of hepatic steatosis. These techniques measure various acoustic parameters, including attenuation coefficient, backscatter coefficient and speckle statistics, speed of sound, and shear wave elastography metrics. In this article, we introduce several representative quantitative ultrasonography techniques and their diagnostic value for the detection of hepatic steatosis.

• 대한의용생체공학회:의공학회지
• /
• 제28권6호
• /
• pp.803-810
• /
• 2007

Although synthetic aperture focusing techniques can improve the spatial resolution of ultrasound imaging, they have not been employed in a commercial product because they require a real-time N-channel beamformer with a tremendously increased hardware complexity for simultaneous beamforming along M multiple lines. In this paper, a hardware-efficient beamformer architecture for synthetic aperture focusing is presented. In contrast to the straightforward design using NM delay calculators, the proposed method utilizes only M delay calculators by sharing the same values among the focusing delays which should be calculated at the same time between the N channels for all imaging points along the M scan lines. In general, synthetic aperture beamforming requires M 2-port memories. In the proposed beamformer, the input data for each channel is first upsampled with a 4-fold interpolator and each polyphase component of the interpolator output is stored into a 2-port memory separately, requiring 4M 2-port memories for each channel. By properly limiting the area formed with the synthetic aperture focusing, the input memory buffer can be implemented with only 4 2-port memories and one short multi-port memory.

• 전자공학회논문지
• /
• 제50권12호
• /
• pp.49-55
• /
• 2013

초음파 의료 영상 응용 분야를 위한 고전압 고집적 아날로그 front-end 집적회로를 0.18-${\mu}m$ 표준 CMOS 반도체 공정을 이용하여 구현하였다. 제안 된 아날로그 front-end 집적회로는 2.6 MHz에서 15 Vp-p 전압까지 동작하는 트랜지스터 stacking구조를 이용한 고전압 펄서와, 저전압에서 동작하는 저잡음 transimpedance 증폭기, 그리고 송신부와 수신부의 분리를 위한 고전압 차단 스위치로 구성되어 있다. 설계 된 집적회로는 $0.15mm^2$ 이하의 작은 면적을 사용함으로써 휴대용 영상 시스템을 포함한 다중 어레이 초음파 의료 영상 시스템에 적용이 가능하다.

• 수산해양기술연구
• /
• 제29권4호
• /
• pp.292-300
• /
• 1993

Acoustical imaging has made brilliant progress in the medical science field, and has also made much progress in the nondestructive testing and under water acoustics applications since doctor Dussik brother has studied about possibilities of making images of brain by recording variations in the intensity of ultrasonic beam from head in 1937. In this paper an acoustical image is reconstructed with the power spectra analysed by impulse ultrasound wave generated by electrodynamic transducer(EDT). The EDT generates the impulse ultrasound of 77KHz in center frequency and 120KHz in bandwidth at -20dB by 1200V exciter in this experiment. The impulse ultrasound has the dominant frequency components of 47KHz, 177KHz, 110KHz and 155KHz. The U shape object is adopted in making an acoustical image. The resulted spectral acoustical images are different from the optical view of the U shape object. However the image reconstructed from 110KHz spectrum is very similar to the original optical shape of the object. Even KHz level impulse sound of 70$\mu$sec pulse width is found to be useful in reconstructing acoustical imaging improvement.

• Journal of Korean Medical Science
• /
• 제33권44호
• /
• pp.279.1-279.16
• /
• 2018

Magnetic resonance-guided focused ultrasound (MRgFUS) is a new emerging neurosurgical procedure applied in a wide range of clinical fields. It can generate high-intensity energy at the focal zone in deep body areas without requiring incision of soft tissues. Although the effectiveness of the focused ultrasound technique had not been recognized because of the skull being a main barrier in the transmission of acoustic energy, the development of hemispheric distribution of ultrasound transducer phased arrays has solved this issue and enabled the performance of true transcranial procedures. Advanced imaging technologies such as magnetic resonance thermometry could enhance the safety of MRgFUS. The current clinical applications of MRgFUS in neurosurgery involve stereotactic ablative treatments for patients with essential tremor, Parkinson's disease, obsessive-compulsive disorder, major depressive disorder, or neuropathic pain. Other potential treatment candidates being examined in ongoing clinical trials include brain tumors, Alzheimer's disease, and epilepsy, based on MRgFUS abilities of thermal ablation and opening the blood-brain barrier. With the development of ultrasound technology to overcome the limitations, MRgFUS is gradually expanding the therapeutic field for intractable neurological disorders and serving as a trail for a promising future in noninvasive and safe neurosurgical care.