• 비파괴검사학회지
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• 제32권5호
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• pp.484-493
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• 2012

초음파를 사용해 음속도, 감쇠 계수, 밀도, 비선형 B/A 파라미터 등을 측정하여 인체 조직의 특성을 정량적으로 영상화하고자 하는 연구가 1980년대부터 많이 진행되어 왔으나 아직 상용화 단계에는 도달하지 못했다. 하지만 1990년대 초에 시작된 탄성 영상법은 최근 들어 초음파 진단기에 상용화되어 임상에서 B-모드 영상법과 함께 전립선, 유방, 갑상선, 간, 혈관 등을 진단하기 위한 보완적이며 더 정량적인 모드로 사용되고 있는 단계에 진입하였다. 본고에서는 주로 준정적 또는 정적탄성 영상법에 사용되는 여러 가지 알고리듬을 소개하고 특성을 비교하고자 한다. 대부분의 알고리듬은 상호상관함수 또는 자기상관함수 방법에 그 기반을 두고 있으며 전자는 래그를 변화시켜가면서 시간 이동량을 찾지만 후자는 보간 과정 없이 고정된 래그에서의 위상차로부터 시간 이동량을 바로 구해 변위를 추정하는 점이다.

• 한국음향학회지
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• 제29권8호
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• pp.504-508
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• 2010

기존의 초음파 의료용 탄성영상에서 변형률 영상을 모니터에 표시할 때 인간 시각 특성을 반영하여 단단한 부위는 어둡게 표시하고 무를수록 밝게 나타낸다. 따라서 종양이나 암이 존재하는 단단한 부위는 어둡게 나타나서 병변 내부의 콘트라스트는 저하되어 나타난다. 병변 영역은 단단하여 변형률 영상에서 어둡게 나타나므로 병변 내부를 좀 더 자세히 진단하는 방법으로, 누른 후의 신호를 누른 변형률만큼 다시 신장시켜서 얻는 전역 균일 신장 방법을 적용하여 영상의 명암을 반전시킴으로써 병변 부분의 콘트라스트를 올리는 방법을 제안하였다. 의료용 초음파 영상 진단기를 이용하여 탄성 모사 팬텀에서 초음파 데이터를 얻어서 제안한 알고리즘을 검증하여 유용성을 확인하였다. 전역 균일 신장 없이 회색조 컬러 맵을 반전해서 얻은 변형률 영상법에 비해 콘트라스트 대 잡음비가 최대 1.8배 정도 향상되었다.

• The Journal of the Acoustical Society of Korea
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• 제27권3E호
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• pp.84-94
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• 2008

Displacement estimation is a crucial step in ultrasonic strain imaging. The displacement between a pre- and postcompression signal in the current data window is estimated by first shifting the postcompression signal by the displacement obtained in the previous data window to reduce their decorrelation and then determining the remaining part of the displacement through autocorrelation and conversion of phase difference into time delay. However, since strain image quality tends to vary with the amount of compression applied, we propose two new methods for enhancing strain image quality, i.e., displacement normalization and adaptive persistence. Both in vitro and in vivo experiments are carried out to acquire ultrasound data and produce strain images in real time under the application of quasi static compression. The experimental results demonstrate that the methods are quite effective in improving strain image quality and thus can be applied to implementing an ultrasound elasticity imaging system that operates in real time.

• 대한의용생체공학회:의공학회지
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• 제24권3호
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• pp.141-149
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• 2003

본 논문에서는 초음파 의용 영상시스템의 B-모드 영상으로 잘 관찰되지 않는 암이나 종양을 진단하기 위하여 인체 연조직의 탄성계수를 측정하여 영상화하는 방법을 제안하였다. 연조직의 단단함을 측정하기 위하여 조직에 정현파 진동을 인가하고 연조직의 기계적인 진동의 크기를 초음파 영상의 스페클 밝기의 시간적 변화를 추정하여 구하였다. 제안한 방법은 B-모드 영상에서 비교적 적은 계산량으로 쉽게 조직의 단단함을 추정할 수 있음을 시뮬레이션과 실험으로 검증하였다

• Imaging Science in Dentistry
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• 제50권1호
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• pp.73-79
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• 2020

Computed tomography (CT) and magnetic resonance imaging (MRI) can be useful for the evaluation of palatal lesions, and strain elastography (performed together with intraoral ultrasonography) is a relatively new sonographic imaging modality. This report describes 2 clinical cases in which strain elastography was used to assess palatal tumors in conjunction with intraoral ultrasonography, CT, and MRI. In the first case, diagnosed as a myoepithelioma, the strain was determined to be 0.000% (strain of normal tissue, 0.556%). In the second case, diagnosed as an adenoid cystic carcinoma, the determined strain was 0.000% (strain of normal tissue, 1.077%). Therefore, we conclude that intraoral strain elastography can be useful for evaluating palatal lesions.

• 한국방사선학회논문지
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• 제15권6호
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• pp.883-889
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• 2021

본 연구는 2020년 5월부터 2020년 12월까지 복부초음파 검사를 위해 내원한 101명의 환자를 대상으로 하였다. 횡파탄성측정검사법을 이용하여 초음파 검사 시 초음파 영상(에코 패턴, 비장비대, 간염) 소견에 따른 탄성도를 알아 알아보고자 하였다. 에코 패턴의 정상 그룹의 횡파탄성측정값은 5.75±1.58 kPa였으며, 에코 패턴의 비정상 그룹은 8.84±4.94 kPa로 에코 패턴 비정상 그룹에서 횡파탄성측정값이 높게 나타났다(p<0.05). 정상 비장 크기에서 간 탄성도 값은 6.33±2.54 kPa였으며, 비장비대의 간 탄성도 값은 13.73±5.48 kPa로 나타났다. 비장비대일 경우 간 탄성도 값이 높게 나타났으며, 통계적으로 유의미한 차이가 있었다(p<0.05). 비장 크기가 증가할수록 간 탄성도 값이 1.485배, 간염이 진행될수록 간 탄성도 값이 1.573배 증가하는 것으로 나타났다(p<0.05). 초음파 영상 소견과 횡파탄성측정법 간 일치도 분석 결과 Kappa 값이 0.922(p<0.05)로 높게 나타났으며, 두 검사 방법 간에 높은 일치도를 보였다. 간 초음파 소견과 함께 횡파탄성측정법 검사의 간 탄성도 값을 추가적으로 비교한다면 간 섬유화 진단에 있어 많은 도움이 될 것으로 생각된다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1391-1395
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• 2006

In non-contact mode atomic force microscopy, the response of a resonating tip is used to measure the nanoscale topography and other properties of a sample surface. However, the tip-surface interactions can affect the tip response and destabilize the non-contact mode control. Especially it is difficult to obtain a good scanned image of high adhesion surfaces such as polymers using conventional hard NCHR tip and non-contact mode control. In this study, experimental investigation is made on the non-contact mode imaging and we report the microcantilever having low stiffness (OMCL) is useful to measure the properties of samples such as elasticity. In addition, we proved that it was adequate to use low stiffness microcantilever to obtain a good scanned image in AFM for the soft and high adhesion sample.

• Korean Journal of Radiology
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• 제21권9호
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• pp.1045-1054
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• 2020

Objective: This study aimed to evaluate the diagnostic value of combining the quantitative parameters of shear wave elastography (SWE) and superb microvascular imaging (SMI) to breast ultrasound (US) to differentiate between benign and malignant breast masses. Materials and Methods: A total of 200 pathologically confirmed breast lesions in 192 patients were retrospectively reviewed using breast US with B-mode imaging, SWE, and SMI. Breast masses were assessed based on the breast imaging reporting and data system (BI-RADS) and quantitative parameters using the maximum elasticity (Emax) and ratio (Eratio) in SWE and the vascular index in SMI (SMI_VI). The area under the receiver operating characteristic curve (AUC) value, sensitivity, specificity, accuracy, negative predictive value, and positive predictive value of B-mode alone versus the combination of B-mode US with SWE or SMI of both parameters in differentiating between benign and malignant breast masses was compared, respectively. Hypothetical performances of selective downgrading of BI-RADS category 4a (set 1) and both upgrading of category 3 and downgrading of category 4a (set 2) were calculated. Results: Emax with a cutoff value of 86.45 kPa had the highest AUC value compared to Eratio of 3.57 or SMI_VI of 3.35%. In set 1, the combination of B-mode with Emax or SMI_VI had a significantly higher AUC value (0.829 and 0.778, respectively) than B-mode alone (0.719) (p < 0.001 and p = 0.047, respectively). B-mode US with the addition of Emax, Eratio, and SMI_VI had the best diagnostic performance of AUC value (0.849). The accuracy and specificity increased significantly from 68.0% to 84.0% (p < 0.001) and from 46.1% to 79.1% (p < 0.001), respectively, and the sensitivity decreased from 97.6% to 90.6% without statistical loss (p = 0.199). Conclusion: Combining all quantitative values of SWE and SMI with B-mode US improved the diagnostic performance in differentiating between benign and malignant breast lesions.

• Asian Pacific Journal of Cancer Prevention
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• 제15권24호
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• pp.10739-10743
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• 2015

The present study aimed at evaluating and comparing the diagnostic performance of B-mode ultrasound (US), elastography score (ES), and strain ratio (SR) for the differentiation of breast lesions. This retrospective study enrolled 431 lesions from 417 in-hospital patients. All patients were examined with both conventional ultrasound and elastography. Two experienced radiologists reviewed ultrasound and elasticity images. The histopathologic result obtained from ultrasound-guided core biopsy or operation excisions were used as the reference standard. Pathologic examination revealed 276 malignant lesions (64%) and 155 benign lesions (36%). A cut-off point of 4.15 (area under the curve, 0.891) allowed significant differentiation of malignant and benign lesions. ROC (receiver-operating characteristic) curves showed a higher value for combination of B-mode ultrasound and elastography for the diagnosis of breast lesions. Conventional ultrasound combined elastography showed high sensitivity, specificity, and accuracy for group II lesions (10mm${\leq}20mm$). Elastography combined with conventional ultrasound show high specificity and accuracy for differentiation of benign and malignant breast lesions. Elastography is particularly important for the diagnosis of BI-RADS 4 and small breast lesions.

• Korean Journal of Acupuncture
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• 제27권1호
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• pp.1-12
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• 2010

Objectives: The purpose of this study is to gain the objective indicators for the classification of hypertension by oriental medical pulse diagnosis, through finding out the parameters which can distinguish the pulse of hypertensive patient from that of normal subject, and characterizes the wiry pulse of hypertension. Methods: 30-59 yr, male, 946 healthy volunteers and 35 hypertensive patients were enrolled in this study. All the hypertensive patients were taking medicine to control the blood pressure and the blood pressure of the hypertension group was not statistically different from that of the normal healthy group. Data were acquired using 3 dimensional pulse imaging analyser(DMP-3000, DAEYOMEDI, KOREA) and analysed according to the age bands and the applied pressure levels. Results: 1. RAI/t, w/t and t2/t decreased with the levels of applied pressure and increased with age in the normal healthy group, not in the hypertension group. 2. RAI/t, w/t, t2/t were significantly higher in the hypertension group than the normal healthy group in the 30-age band, and elasticity coefficient was higher in the hypertension group than the normal healthy group in the 40-age band. 3. Researches on the patients without hypotensive agents are needed to figure out whether these parameters are the components of hypertensive wiry pulse. Conclusions: Analysing the radial pulse at 5 applied pressure levels using 3 dimensional pulse imaging analyser may be useful to differentiate the pulses of the hypertensive patients from those of the normal subjects, and characterize the hypertension.