• Title/Summary/Keyword: Medical ultrasound imaging

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Endoscopic Bio-Imaging Using Optical Coherence Tomography (마이크로 내시경 및 첨단 광 단층촬영기법을 이용한 생체 이미징)

  • Ahn, Yeh-Chan;Brenner, Matthew;Chen, Zhongping
    • Journal of the Korean Society for Nondestructive Testing
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    • v.31 no.5
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    • pp.466-471
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    • 2011
  • Optical coherence tomography(OCT) is an emerging medical diagnostic tool that draws great attention in medical and biological fields. It has a 10-100 times higher spatial resolution than that of the clinical ultrasound but lower imaging depth such as 1-2 mm. In order to image internal organs, OCT needs an endoscopic probe. In this paper, the principle of Fourier-domain optical coherence tomography with high-speed imaging capability was introduced. An OCT endoscope based on MEMS technology was developed. It was attached to the Fourier-domain OCT system to acquire three-dimensional tomographic images of gastrointestinal tract of New Zealand white rabbit. The endoscope had a two-axis scanning mirror that was driven by electrostatic force. The mirror stirred an incident light to sweep two-dimensional plane by scanning. The outer diameter of the endoscope was 6 mm and the mirror diameter was 1.2 mm. A three-dimensional image rendered by 200 two-dimensional tomographs with $200{\times}500$ pixels was displayed within 3.5 seconds. The spatial resolution of the OCT system was 8 ${\mu}m$ in air.

가중 쳐프 신호를 사용한 초음파 고조파 영상 기법

  • 김동열;이종철;권성재;송태경
    • Journal of Biomedical Engineering Research
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    • v.23 no.1
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    • pp.61-72
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    • 2002
  • In this parer, a new harmonic imaging technique is Proposed and evaluated experimentally. In the Proposed method. a weighted chirp signal with a hanning window is transmitted. The RF samples obtained on each array element are individually compressed by correlating with the reference signal defined as the 2nd harmonic component($2f_0$) of a transmitted chirp signal generated in a square-law system. The correlator output will then consist of the compressed version of the $2f_0$ component generated in tissue and the crosscorrelation sequence of the fundamental($f_0$) and 2f$_{0}$components. The Proposed method uses the compressed $2f_0$ component to form an image. for which the crosscorrelation term should be suppressed below at least -50dB. The Proposed method has two process, 2f$_{0}$-correlation and $2f_0$-correlation(PI) . $2f_0$-correlation can successfully eliminate the $f_0$ component with a single transmit-receive events and therefore is more efficient than the conventional Pulse inversion method in terms of the frame rate. 2i)-correlation(Pl) Performs pulse compression after applying pulse inversion method for the 2nd harmonic image with high resolution and SNR. Another advantage of the proposed method is that the SNR of 2nd harmonic imaging can be improved without limitation by increasing the duration of the chirp signal. The proposed method was verified through both the computer simulations and actual experiments .ts .

Deep Learning-Based Lumen and Vessel Segmentation of Intravascular Ultrasound Images in Coronary Artery Disease

  • Gyu-Jun Jeong;Gaeun Lee;June-Goo Lee;Soo-Jin Kang
    • Korean Circulation Journal
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    • v.54 no.1
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    • pp.30-39
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    • 2024
  • Background and Objectives: Intravascular ultrasound (IVUS) evaluation of coronary artery morphology is based on the lumen and vessel segmentation. This study aimed to develop an automatic segmentation algorithm and validate the performances for measuring quantitative IVUS parameters. Methods: A total of 1,063 patients were randomly assigned, with a ratio of 4:1 to the training and test sets. The independent data set of 111 IVUS pullbacks was obtained to assess the vessel-level performance. The lumen and external elastic membrane (EEM) boundaries were labeled manually in every IVUS frame with a 0.2-mm interval. The Efficient-UNet was utilized for the automatic segmentation of IVUS images. Results: At the frame-level, Efficient-UNet showed a high dice similarity coefficient (DSC, 0.93±0.05) and Jaccard index (JI, 0.87±0.08) for lumen segmentation, and demonstrated a high DSC (0.97±0.03) and JI (0.94±0.04) for EEM segmentation. At the vessel-level, there were close correlations between model-derived vs. experts-measured IVUS parameters; minimal lumen image area (r=0.92), EEM area (r=0.88), lumen volume (r=0.99) and plaque volume (r=0.95). The agreement between model-derived vs. expert-measured minimal lumen area was similarly excellent compared to the experts' agreement. The model-based lumen and EEM segmentation for a 20-mm lesion segment required 13.2 seconds, whereas manual segmentation with a 0.2-mm interval by an expert took 187.5 minutes on average. Conclusions: The deep learning models can accurately and quickly delineate vascular geometry. The artificial intelligence-based methodology may support clinicians' decision-making by real-time application in the catheterization laboratory.

Comparative Investigation of Single Voxel Magnetic Resonance Spectroscopy and Dynamic Contrast Enhancement MR Imaging in Differentiation of Benign and Malignant Breast Lesions in a Sample of Iranian Women

  • Faeghi, Fariborz;Baniasadipour, Banafsheh;Jalalshokouhi, Jalal
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.18
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    • pp.8335-8338
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    • 2016
  • Purpose: To make a comparison of single voxel magnetic resonance spectroscopy (SV-MRS) and dynamic contrast enhancement (DCE) MRI for differentiation of benign and malignant breast lesions in a sample of Iranian women. Materials and Methods: A total of 30 women with abnormal breast lesions detected in mammography, ultrasound, or clinical breast exam were examined with DCE and SV-MRS. tCho (total choline) resonance in MRS spectra was qualitatively evaluated and detection of a visible tCho peak at 3.2 ppm was defined as a positive finding for malignancy. Different types of DCE curves were persistent (type 1), plateau (type 2), and washout (type 3). At first, lesions were classified according to choline findings and types of DCE curve, finally being compared to pathological results as the standard reference. Results: this study included 19 patients with malignant lesions and 11 patients with benign ones. While 63.6 % of benign lesions (7 of 11) showed type 1 DCE curves and 36.4% (4 of 11) showed type 2, 57.9% (11of 19) of malignant lesions were type 3 and 42.1% (8 of 19) type 2. Choline peaks were detected in 18 of 19 malignant lesions and in 3 of 11 benign counterparts. 1 malignant and 8 benign cases did not show any visible resonance at 3.2 ppm so SV-MRS featured 94.7% sensitivity, 72.7 % specificity and 86.7% accuracy.Conclusions: The present findings indicate that a combined approach using MRS and DCE MRI can improve the specificity of MRI for differentiation of benign and malignant breast lesions.

Intra- and inter-rater reliability of muscle thickness measurement of the tibialis anterior using different inward pressures

  • Lee, Seong-Joo;Lim, Ji Young;Lee, Chang-Hyung;Park, Dae-Sung
    • Physical Therapy Rehabilitation Science
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    • v.8 no.4
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    • pp.218-224
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    • 2019
  • Objective: This reliability study examined the effects of applying varying induced inward pressures using a transducer placed at 0° neutral ankle position (NEU) and 15° ankle dorsiflexion (DF) on tibialis anterior (TA) muscle thickness using a custom-made device with a force indicator during rehabilitative ultrasound imaging. Design: Cross-sectional study. Methods: Twenty-four healthy subjects were recruited in this study. Two examiners measured the muscle thickness of the TA at 0° NEU and 15° DF in 3 conditions of inward pressures (1.0 N, 2.0 N, and 4.0 N) using a custom-made holder. The muscle thickness was measured three times for each of the conditions arranged in random order. For intra- and inter-rater reliability, the intraclass correlation coefficients (ICCs) with 95% confidence intervals, standard error of measurement, minimal detectable change, and coefficient of variation were analyzed. One-way repeated measures analysis of variance was conducted for investigating changes of TA muscle thickness according to the inward pressures of the transducers. Results: The intra-rater reliability of TA muscle thickness measurement was excellent (ICC3,1: 0.92-0.96) for all conditions (at both ankle joint angles per varying inward pressure). Likewise, the inter-rater reliability of TA muscle thickness measurement was excellent (ICC2,1: 0.89-0.97) under same conditions. The mean of TA thickness showed the trend of decreasing significantly with increased inward pressures at all ankle joint angles (p<0.05). Conclusions: Use of this custom-made device with a force indicator is useful to accomplish the high intra- and inter-rater reliability of TA muscle thickness measurement at both ankle joint angles in reducing the measurement error.

Influences of the Defective Piezo-Elements of a Medical Ultrasonic Probe on Transient Acoustic Fields and B-Mode Images (의료용 초음파프로브의 압전소자 결함이 과도음장과 B-모드 영상에 미치는 영향)

  • Choi, Kwang-Yoon;Ha, Kang-Lyeol;Kim, Moo-Joon;Kim, Jung-Soon;Yang, Jeong-Hwa;Kang, Gwan-Suk;Choi, Min-Joo
    • The Journal of the Acoustical Society of Korea
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    • v.29 no.8
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    • pp.476-482
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    • 2010
  • The ultrasonic transient fields and B-mode images of a point target which were simulated for a medical ultrasonic probe with a few defective piezo-elements were compared with those for a normal probe. The present study considered a 3.5 MHz linear array probe whose acoustic beam was formed by the 64 active elements of total 192 elements. The results showed that the maximum amplitude and -3 dB width of the acoustic fields by main-lobes decreased linearly as the defective element number increased from one to four. However, the depths of foci remained almost unchanged, and the pressure differences between main-lobes and side-lobes tended to decrease due to rise in pressures in side-lobes. Such changes in ultrasonic fields affected the B-mode images of point targets. So the artifacts were formed in the right and left side of the target, and the lateral spatial resolutions were decreased while the axial resolution was almost the same.

A Performance Improvement of Ultrasonic Diagnosis Transducer by Transient Acoustic Field Analysis (과도음장 해석을 통한 초음파 진단 탐촉자의 성능 개선)

  • 박은주;송행용;김무준;김동현;이수성;하강열
    • The Journal of the Acoustical Society of Korea
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    • v.21 no.8
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    • pp.744-756
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    • 2002
  • The transient acoustic fields formed by a 3.5 ㎒ curved linear array transducer which is commonly used in ultrasonic medical imaging system for diagnosis of abdomen are systematically analyzed to obtain new design parameters for the better acoustic image. In the analysis with an assumption of radiating waveform, element size, radius of curvature, amplitude apodization are considered as parameters giving constitutive relations with the fields. As simulation results, appropriate new parameters with the reduced curvature and elevation aperture and the apodization of Hamming window, which make an improved acoustic beam with lower side lobe levels than a conventional typical transducer, are obtained.

Digital Scan Converter Algorithm for Ultrsound Sector Scanner (초음파 섹터 스캐너를 위한 디지털 스캔 변환 기법)

  • 김근호;오정환
    • Journal of Biomedical Engineering Research
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    • v.17 no.4
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    • pp.469-478
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    • 1996
  • In the conventional digital ultrasound scanner, the reflected signal is sampled either in polar coordinates of R-$\theta$ method, or in Cartesian coordinates of uniform ladder algorithm (ULA). The R-$\theta$ scan method necessitates a coordinate transform process which makes hardware complex in comparison with ULA scan mrthoA In spite of this complexity, R-$\theta$ method has a good resolution in ultrasonographic (US) image, since scan direction of the US imaging is a radial direction. In this paper, a new digital scan converter is proposed, which is named the radius uniform ladder algorithm (RULA). The RULA has the rome scan direction as the US scanning in the radial direction and as the display space in the $\theta$ direction. In tllis new approach, sampled points we uniformly distributed in each horizontal line i.n well as in each radial ray so that the data are displayed in the Cartesian coordinates by the 1-D interpolation process. The propped algorithm has an uniform resolution in the periphery and the center field in comparison with equi-angle ULA and equi-interval ULA. To extend the scan angle, concentric square raster sampling (CSRS) is adopted with reduction of discontinuities on the junctions between horizontal scan and vertical scan. The discontinuities are reduced by using the hmction filtering along the $\theta$ direction.

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Comparisons of Abdominal Muscles Thickness During Single Leg Holding Exercise on Stable Surface and on a Foam Roller Using Ultrasound Imaging (안정된 면과 폼 롤러 위에서 한 발 들기 자세 시 초음파를 이용한 복근들의 두께 양상 비교)

  • Jung, Do-Young;Koh, Eun-Kyung;Kim, Su-Jeong;Kwon, Oh-Yun
    • Korean Journal of Applied Biomechanics
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    • v.20 no.4
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    • pp.415-420
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    • 2010
  • The purpose of this study was to compare the thickness of the abdominal muscles during single leg holding exercise (SLH) in a hooked lying position on stable surface and on a foam roller. Healthy twenty subjects who had no medical history of lower extremity or lower back pain were recruited for this study. Muscle thickness of transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) was recorded using real-time ultrasonography during SLH. Paired t-test with Bonferroni adjustment was used to compare the muscles thickness during SLH on stable surface and on a foam roller. The result showed that TrA and IO muscle demonstrated greater thickness during SLH on foam roller than those on the stable surface. This finding suggests that SLH on an unstable foam roller is more effective to increase thicknesses of TrA and IO muscles than stable surface.

A Case of Epiploic Appendagitis Presented with Right Lower Quadrant Pain of Abdomen (우하복부 통증을 주소로 내원한 복막수염(Epiploic Appendagitis) 1예)

  • Kang, Hyo Cheol;Nam, Ji Hyung;Jeon, Se Yun;Yoo, Gyeong Hee;Kim, Young Tong
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • v.9 no.1
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    • pp.98-102
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    • 2006
  • An inflammation of an epiploic appendage is a relatively rare cause of acute abdominal pain. It can be clinically misdiagnosed as either acute appendicitis or diverticulitis. Judicious interpretation of imaging with ultrasound or computed tomography may lead to an early diagnosis and prevent unnecessary surgical or medical treatment. Conservative treatment of symptoms is usually sufficient. We have experienced a case of epiploic appendagitis treated by conservative management and report this case with the review of the literature.

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