• Korean Journal of Radiology
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• 제2권4호
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• pp.197-203
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• 2001

Objective: To compare the clinical utility of contrast-enhanced color Doppler US in the differentiation of retinal detachment (RD) from vitreous membrane (VM) with that of various conventional US modalities, and to analyze the enhancement patterns in cases showing an enhancement effect. Materials and Methods: In 32 eyes examined over a recent two-year period, RD (n=14) and VM (n=18) were confirmed by surgery (n=28) or clinical follow-up (n=4). In all cases, gray-scale, color Doppler, and power Doppler US were performed prior to contrast injection, and after the intravenous injection of Levovist (Schering, Berlin) by hand for 30 seconds at a dose of 2.5 g and a concentration of 300 mg/mL via an antecubital vein, contrast-enhanced color Doppler US was performed. At Doppler US, the diagnostic criterion for RD and VM was whether or not color signals were visualized in membranous structures. Results: Diagnostic accuracy was 78% at gray-scale US, 81% at color Doppler US, 59% at power Doppler US, and 97% at contrast-enhanced color Doppler US. The sensitivity of color Doppler US to color signals in RD increased from 57% to 93% after contrast enhancement. The enhancement patterns observed were signal accentuation (n=3), signal extension (n=2), signal addition (n=3), and new signal visualization (n=5). Conclusion: Contrast-enhanced color Doppler US was the most accurate US modality for differentiating RD from VM, showing a significantly increased signal detection rate in RD.

• Korean Journal of Radiology
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• 제22권5호
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• pp.677-687
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• 2021

Microvascular ultrasound (US) techniques are advanced Doppler techniques that provide high sensitivity and spatial resolution for detailed visualization of low-flow vessels. Microvascular US imaging can be applied to breast lesion evaluation with or without US contrast agents. Microvascular US imaging without a contrast agent uses a sophisticated wall filtering system to selectively obtain low-flow Doppler signals from overlapped artifacts. Microvascular US imaging with second-generation contrast agents amplifies flow signals and makes them last longer, which facilitates hemodynamic evaluation of breast lesions. In this review article, we will introduce various microvascular US techniques, explain their clinical applications in breast cancer diagnosis and radiologic-histopathologic correlation, and provide a summary of a recent radiogenomic study using microvascular US.

• Korean Journal of Radiology
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• 제1권4호
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• pp.191-197
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• 2000

Because US plays a key role in the initial evaluation of hepatic hemangiomas, knowledge of the entire spectrum of US appearances of these tumors is important. Most hemangiomas have a distinctive US appearance, and even with those with atypical appearances on conventional gray-scale US, specific diagnoses can be made using pulse-inversion harmonic US with contrast agents. In this essay, we review the spectrum of US appearances of hepatic hemangiomas on conventional gray-scale, power Doppler, and pulse-inversion harmonic US with contrast agents.

• Korean Journal of Radiology
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• 제2권1호
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• pp.57-60
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• 2001

In stenosis of a segmental branch or among multiple renal arteries, Doppler sampling of intrarenal arteries in the upper, mid and lower poles demonstrates strikingly different waveform patterns that might otherwise be overlooked. We report a case of segmental branch renal artery stenosis in which a pulsus parvus et tardus waveform was observed in a segmental branch of a renal artery. In this case, systematic analysis of Doppler waveforms of intrarenal arteries at more than three different locations facilitated a rapid and confident diagnosis of segmental branch renal artery stenosis.

• 대한치과의사협회지
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• 제57권11호
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• pp.690-699
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• 2019

Ultrasound sonography(US) is used to evaluate various diseases of maxillofacial region including salivary glands, soft tissue and jaw lesions because of easy accessibility and no hazard of ionizing radiation. Also, US can offer dynamic study showing real-time images during diagnostic or surgical procedure. US images provide accurate information about the internal features of lesions on the jaw prior to surgical treatment. Doppler images are used to visualize the vascular distribution of the lesions and to provide additional information to enhance diagnostic value. Nevertheless, the clinical application of US imaging is limited in the dental field. This is due to the lack of knowledge about the US image and the image characteristics of the anatomical structures. It is necessary to evaluate the diagnostic value of US and evaluate its usefulness by looking at clinical cases using US images. Therefore, US imaging may be recommended as an assistant image in evaluating jaw lesions. US images provided accurate information about the internal structure of lesions on the jaw prior to surgical treatment, and diagnostic value was enhanced by visualizing the vascular distribution of the lesion using doppler imaging.

• Korean Journal of Radiology
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• 제23권1호
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• pp.52-59
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• 2022

Objective: To investigate whether the diagnostic performance of CT angiography (CTA) could be improved by modifying the conventional criterion (anastomosis site abnormality) to diagnose hepatic artery occlusion (HAO) after liver transplantation (LT) in suspected patients with Doppler ultrasound (US) abnormalities. Materials and Methods: One hundred thirty-four adult LT recipients (88 males and 46 females; mean age, 52.7 years) with suspected HAO on Doppler US (40 HAO and 94 non-HAO according to the reference standards) were included. We evaluated 1) abnormalities in the HA anastomosis, categorized as a cutoff, ≥ 50% stenosis at the anastomotic site, or diffuse stenosis at both graft and recipient sides around the anastomosis, and 2) abnormalities in the distal run-off, including invisibility or irregular, faint, and discontinuous enhancement. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the conventional (considering anastomosis site abnormalities alone) and modified CTA criteria (abnormalities in both the anastomosis site and distal run-off) for the diagnosis of HAO were calculated and compared using the McNemar test. Results: By using the conventional criterion to diagnose HAO, the sensitivity, specificity, PPV, NPV, and accuracy were 100% (40/40), 74.5% (70/94), 62.5% (40/64), 100% (70/70), and 82.1% (110/134), respectively. The modified criterion for diagnosing HAO showed significantly increased specificity (93.6%, 88/94) and accuracy (93.3%, 125/134) compared to that with the conventional criterion (p = 0.001 and 0.002, respectively), although the sensitivity (92.5%, 37/40) decreased slightly without statistical significance (p = 0.250). Conclusion: The modified criterion considering abnormalities in both the anastomosis site and distal run-off improved the diagnostic performance of CTA for HAO in suspected patients with Doppler US abnormalities, particularly by increasing the specificity.

• Imaging Science in Dentistry
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• 제48권3호
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• pp.153-160
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• 2018

Purpose: This study aimed to assess the reliability of ultrasonography (US) in comparison with cone-beam computed tomography (CBCT) as a tool for monitoring the healing of jaw lesions. Materials and Methods: Twenty-one radiolucent lesions in jaws referred to the Oral Surgery Department at our institution were selected for this study. All lesions underwent CBCT and US examinations. The anteroposterior, superoinferior, and mesiodistal dimensions of the lesions were measured on CBCT and US images before surgery and at 6 months after surgery. The dimensions were compared between the US and CBCT images. Blood-flow velocity around the lesions was measured by color Doppler before surgery and at 1 week and 6 months after surgery to assess the capability of US to show changes in blood-flow velocity around the lesion. Results: Before surgery, there were no significant differences between US and CBCT in the mesiodistal and anteroposterior dimensions, although a significant difference was found in the superoinferior dimension (P<.05). However, at 6 months after surgery, significant differences were found between US and CBCT in all dimensions, and it is likely that the US measurements more accurately reflected the extent of healing. The average blood-flow velocity increased at 1 week after surgery (5.84 cm/s) compared with the velocity before surgery (4 cm/s) (P<.05). Then, at 6 months after surgery, the blood-flow velocity significantly decreased (3.53 cm/s) compared to the velocity measured at 1 week after surgery (P<.05). Conclusion: US with color Doppler was confirmed to be a more efficient tool than CBCT for monitoring bone healing.

• 대한치과의사협회지
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• 제55권11호
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• pp.778-788
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• 2017

Ultrasound sonography(US) is used to evaluate various diseases of oral and maxillofacial region including salivary glands, soft tissue and jaw lesions because of easy accessibility and no hazard of ionizing radiation. Also, US can offer dynamic study showing real-time images during diagnostic or surgical procedure. US images provide accurate information about the internal features of lesions on the jaw prior to surgical treatment. Doppler images are used to visualize the vascular distribution of the lesions and to provide additional information to enhance diagnostic value. It is necessary to evaluate the diagnostic value of US and evaluate its usefulness by looking at clinical cases using US images. Therefore, US imaging may be recommended as an assistant image in evaluating jaw lesions. US images provided accurate information about the internal structure of lesions on the jaw prior to surgical treatment, and diagnostic value was enhanced by visualizing the vascular distribution of the lesion using doppler imaging. We report the protocol and suggest the effectiveness of US for various lesions and US-guided sialography.

• Korean Journal of Radiology
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• 제1권4호
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• pp.219-222
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• 2000

Renal inflammatory pseudotumor is a very rare benign condition of unknown etiology characterized by proliferative myofibroblasts, fibroblasts, histiocytes, and plasma cells. In the case we report, the lesion appeared on contrast-enhanced power Doppler US images as a well-defined hypoechoic mass with intratumoral vascularity, and on CT as a low-attenuated mass. Differentiation from malignant renal neoplasms was not possible.

• 한국음향학회지
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• 제21권5호
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• pp.446-454
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• 2002

본 연구는 이동 표적체에서 주파수가 서로 다른 신호가 서로 다른 위치에서 발생할 때 도플러 주파수 편이량을 추정하여 이들의 상대적인 신호 발생 위치를 추적하는 도플러 스캐닝 기법에 관한 연구이다. 예를 들어 선박의 발전기와 프로펠러 등과 같은 탑재 기계장치들의 진동에 의해 야기되는 기계적 소음의 각 특징 주파수들의 도플러 주파수 편이는 최단근접거리 (CPA: Closest Point of Approach)에 따라 유일한 시간 정보를 갖고 각 소음원들의 위치에 관련되는 함수이다. 따라서 도플러 스캐닝 기법을 적용하면 이동 선박의 각 기계적 소음원들간의 공간적인 상대 위치 추정이 가능하다. 그러나 일반적으로 기계류 소음의 주파수는 저주파수대역이므로 도플러 주파수 편이량을 추정하기 위해서는 주파수 분해능이 높아야 하고 아울러 탑재장치의 공간분해능을 높이기 위해서는 동시에 시간 분해능이 높아야 한다. 따라서 상호 역비례 관계에 있는 이들 분해능을 동시에 높이기 위해 확장 칼만 필터 알고리즘을 적용하여 특징 신호들의 도플러 주파수 편이량을 추정하여 기계류의 상대적인 탑재 위치를 규명할 수 있음을 보인다. 먼저 수치모의 실험으로 그 가능성을 검증하고 자동차에 탑재된 스피커 음원을 사용한 실험 결과를 통해 그 성능을 확인하도록 한다.