• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.621-628
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• 2021

Prior studies on frequency-related image quality analysis of intravascular ultrasound catheters are lacking both in Korea and abroad. Therefore, this study was conducted to prepare a standard for measuring the image quality using the program and to suggest a measuring method to researchers related to the quality analysis of intravascular ultrasound images. For the target, the vessel lumen size is 3.0 - 4.0 mm. Before using intravascular ultrasound, thoroughly clean the ultrasound catheter so that no air or foreign substances enter it. Normal vascular images and lesion vascular images of sufficiently dilated images were used. As a standard image acquisition method, the image of the end-systolic section, which has the best evaluation of vascular lesions when using intravascular ultrasound, was acquired retrospectively through the DCAS PACS program to set the standard. When setting the measurement method criteria, we proposed a standard setting method that corresponds to the concentric and eccentric circles of normal and lesion vessels. By applying this criterion, we proposed a method for measuring the lumen and lateral cavities of normal and lesion vessels of interest and background area. In conclusion, if the image quality of intravascular ultrasonography is measured through the method devised by these researchers, consistent quality measurement is possible regardless of the type of intravascular ultrasound catheter. Therefore, it is thought that it can be applied as a guideline for the actual image quality measurement method in the study related to intravascular ultrasound image quality.

• Journal of Yeungnam Medical Science
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• v.35 no.1
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• pp.121-126
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• 2018

Coronary spasm generally occurs in patients with minimal atherosclerotic plaque lesion, and it has a rather favorable prognosis. However, in some cases, coronary spasm may induce myocardial infarction and even sudden cardiac death (SCD). Here, we report a case in which multi-vessel intractable coronary vasospasm suddenly occurred in a diffuse atherosclerotic lesion after percutaneous coronary intervention (PCI) in a patient with aborted SCD. We identified the characteristics of the spasm portion in intravascular ultrasound (IVUS) images and conducted percutaneous cardiopulmonary bypass support-PCI with stenting as treatment. Intima and media thickening and a large attenuated plaque burden with rupture were identified in IVUS images at the obstructive spasm portion.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.05
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• pp.27-31
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• 1994

Intravascular ultrasound images of coranary artery contain very important informations on heart disease. The intimal contours on the image show informations and data to examine intravascular problems of patients. A new computation algorithm to detect the intimal and adventitial contours from the intravascular images was developed. An Image processing on gray level image was used. It uses arrays of pixels in each radial lines on the images. A "Robert" filter was adopted at first step for one dimensional image processing. Some other calculation techniques were developed to inclose the accuracy of automatically detected contours. The standard contour data to compare with automatically detected contour data were obtained through manually tracing by experienced cardiological medical doctors. The result of the new algorithm shows high accuracy of 80 % matching with the standard contour data.

• The Journal of the Acoustical Society of Korea
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• v.37 no.4
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• pp.215-222
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• 2018

This paper reports the development and performance evaluation of a backend system for real-time IVUS (Intravascular Ultrasound) imaging. The developed backend system was designed to minimize the amount of logic and memory usage by means of efficient LUTs (Look-up Tables), and it was implemented in a single FPGA (Field Programmable Gate Array) without using external memory. This makes it possible to implement the backend system that is less expensive, smaller, and lighter. The accuracy of the backend system implemented was evaluated by comparing the output of the FPGA with the result computed using a MATLAB program implemented in the same way as the VHDL (VHSIC Hardware Description Language) code. Based on the result of ex-vivo experiment using rabbit artery, the developed backend system was found to be suitable for real-time intravascular ultrasound imaging.

• Biomedical Science Letters
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• v.11 no.1
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• pp.23-29
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• 2005

Molecular imaging with targeted contrast agents enables tissues to be distinguished by detecting specific cell-surface receptors. In the present study, a ligand-targeted acoustic nanoparticle system is used to identify angioplasty-induced expression of tissue factor by smooth muscle cell within carotid arteries. Pig carotid arteries were overstretched with balloon catheters, treated with tissue factor-targeted or a control nanoparticle system, and imaged with intravascular ultrasound before and after treatment. Tissue factor-targeted emulsion bound and increased the echogenicity and gray-scale levels of overstretched smooth muscle cell within the tunica media, versus no change in contralateral control arteries. Expression of stretch-induced tissue factor in carotid artery media was confirmed by immunohistochemistry. The potential for abnormal thrombogenicity of balloon-injured arteries, as reflected by smooth muscle expression of tissue factor, was imaged using a novel, targeted, nanoparticulate ultrasonic contrast agent.

• The Korean Journal of Pain
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• v.28 no.2
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• pp.122-128
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• 2015

Background: Caudal epidural injections have been commonly performed in patients with low back pain and radiculopathy. Although caudal injection has generally been accepted as a safe procedure, serious complications such as inadvertent intravascular injection and dural puncture can occur. The present prospective study was designed to investigate the influence of the depth of the inserted needle on the success rate of caudal epidural blocks. Methods: A total of 49 adults scheduled to receive caudal epidural injections were randomly divided into 2 groups: Group 1 to receive the caudal injection through a conventional method, i.e., caudal injection after advancement of the needle 1 cm into the sacral canal (n = 25), and Group 2 to receive the injection through a new method, i.e., injection right after penetrating the sacrococcygeal ligament (n = 24). Ultrasound was used to identify the sacral hiatus and to achieve accurate needle placement according to the allocated groups. Contrast dyed fluoroscopy was obtained to evaluate the epidural spread of injected materials and to monitor the possible complications. Results: The success rates of the caudal injections were 68.0% in Group 1 and 95.8% in Group 2 (P = 0.023). The incidences of intravascular injections were 24.0% in Group 1 and 0% in Group 2 (P = 0.022). No intrathecal injection was found in either of the two groups. Conclusions: The new caudal epidural injection technique tested in this study is a reliable alternative, with a higher success rate and lower risk of accidental intravascular injection than the conventional technique.

• The KIPS Transactions:PartB
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• v.19B no.3
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• pp.201-208
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• 2012

Accurately segmenting lumen border in intravascular ultrasound images (IVUS) is very important to study vascular wall architecture for diagnosis of the cardiovascular diseases. After each of IVUS image is transformed to a polar coordinated image, initial points are detected using wavelet transform. Then, lumen border is initialized as the set of important points using non parametric probability density function and smoothing function by removing outlier initial points occurred by noises and artifacts. Finally, polynomial curve fitting is applied to obtain real lumen border using filtered important points. The evaluation of proposed method was performed with related method and the proposed method produced accurate lumen contour detection when compared to another method in most types of IVUS images.

• The Journal of the Acoustical Society of Korea
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• v.33 no.5
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• pp.300-308
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• 2014

Photoacoustic imaging is a useful tool for the diagnosis of atherosclerosis because it is capable of providing anatomical and pathological information at the same time. A photoacoustic signal detector is a pivotal element to achieve high spatial resolution, so that it should have broadband spectrum with a high center frequency. Since a photoacoustic imaging probe is directly inserted into blood vessel to diagnose atherosclerosis, the total size of the photoacoustic signal detector should be less than 1 mm. The main purpose of this paper is to demonstrate that PVDF can be used as an active material for the photoacoustic signal detector with a high frequency and broadband characteristic. The photoacoustic signal detector developed in this study was a single element ultrasound transducer with an aperture of $0.5{\times}0.5mm$ and the total size of 1 mm. In the design stage, the natural focal depth was adjusted for an effective focal area to cover the region of interest, i.e., 1~5 mm in depth. This was because geometrical focusing could not be used due to the small aperture. Through a pulse-echo test, it was ascertained that the developed photoacoustic signal detector has the -6 dB bandwidth ranging between 40.1 and 112.8 MHz and the center frequency of 76.83 MHz.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.79-83
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• 1997

A new computation algorithm to detect the intimal and adventitial contours from the intravascular images was developed. An image processing on gray level image was used. It uses arrays of pixels in each radial lines on the images. A Low-Pass filters was adopted at first step for one dimensional image processing. Some other calculations techniques were developed to increase the accuracy of automatically detected contours. The program implemented in C++ as a window95-base application.

• The Journal of the Acoustical Society of Korea
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• v.36 no.4
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• pp.238-246
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• 2017

High frequency ultrasound imaging typically suffers from low sensitivity due to the small aperture of high frequency transducers and shallow imaging depth due to the frequency-dependent attenuation of ultrasound. These limitations should be overcome to obtain high-frequency, high- resolution ultrasound images. One practical solution to the problems is a high-performance signal receiver capable of detecting a very small signal and amplifying the signal with minimal electronic noise addition. This paper reports a recently developed low-noise, wideband ultrasound receiver for high-frequency, high-resolution ultrasound imaging. The developed receiver has an amplification gain of up to 73 dB and a variable amplification gain range of 48 dB over an operating frequency of 80 MHz. Also, it has an amplification gain flatness of ${\pm}1dB$. Due to these high performances, the developed receiver has a signal-to-noise ratio of at least 8.4 dB and a contrast-to-noise ratio of at least 3.7 dB higher than commercial receivers.