• 대한디지털의료영상학회논문지
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• 제11권2호
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• pp.51-57
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• 2009

The purpose of this study would evaluate if having clinical effects on diffusion image with quantitative analysis through ADC values of brain's normal tissue and lesions before and after contrast injections using a 3.0T. From November in 2007 until December in 2008, a total of 32 patient was performed on 3.0T(Signa Excite, GE Medical System, USA) with the normal or lesions in the patient who requests diffusion weighted image with 8channel head coil. The pulse sequence was used with spin echo EPI(TR: 10000msec, TE: 72.2 msec, Matrix: 128*128, FOV: 240 mm, NEX: 1, diffusion direction: 3, b-value: 1000). Measurement results of ADC values on lesions, CSF, white matter, gray matter, lesions after contrast injection were measured less 75% than before contrast injection, infarction: 100%, CSF: 78%(high), white matter: 71.4%(low), gray matter: 50%(high, low). The results of paired t-test on the deference of ADC values which statically is significant in three(lesions, CSF, white matter)regions except for white matter(p<0.05). Quantitative analysis of lesions, CSF, white matter, gray matter have difference on all regions. ADC values were low in lesions and white matter, normal CSF after contrast injection commonly is high than before contrast injection, ADC values which white matter were high and low (50:50) after contrast injection. 3.0T diffusion weighted image clinically supposed that performing DWI examination after contrast injection was not desirable because of having effects on brain tissue.

• 한국콘텐츠학회논문지
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• 제19권11호
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• pp.445-450
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• 2019

본 연구는 자기공명영상 동적검사 시 자동주입기의 사용에 따라 조영제 역류로 인한 생리식염수의 오염 현상을 실험적으로 증명함으로써, 오염된 실린지 재사용 문제의 심각성을 인식시키고자 하였다. 연구방법은 조영제 주입 전 생리식염수와 주입 후 생리식염수를 각각 채취한 다음, T1 강조영상을 획득하여 신호강도를 측정하여 비교하였다. 생리식염수의 주입 후 신호강도가 주입 전에 비해 523.43% 통계적으로 높게 나타났다(p<0.05). 이는 조영제 주입에 따른 압력에 의해 조영제가 관을 통해 역류하여 압력이 낮은 반대쪽 생리식염수를 오염시킨 것으로 분석되었다. 결론적으로 조영제 주입 시 사용하는 실린지는 조영제 역류로 인해 교차오염이 발생하므로 정량적 분석을 위한 검사 시 동일한 환자의 검사라도 검사순서를 변경하거나 실린지를 교체하여 오류를 방지해야 한다.

• Journal of Microbiology and Biotechnology
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• 제18권11호
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• pp.1762-1767
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• 2008

Image contrast of whole bacteria was compared in Staphylococcus aureus and Escherichia coli depending on pre-stain suspension liquids by energy-filtering transmission electron microscopy. The two bacterial strains were suspended in three most commonly used liquids for negative staining (triple distilled water [DW], phosphate-buffered saline [PBS], and nutrient broth [NB]) and directly observed without staining or stained with neutralized potassium phosphotungstate (PTA), respectively. Even though in low contrast, unstained bacteria were observed owing to their inherent electron density and cell shape in zero-loss (elastic scattering) images. After being suspended in PBS, unstained bacteria appeared to have higher contrast and more refined periphery than DW-suspended ones, and extracellular appendage structures such as fimbriae and flagella could be discerned. The unstained bacteria appeared to be invariably surrounded with electron-lucent precipitates, possibly from PBS. As far as delineation of the structures, the combination of DW or PBS suspension with subsequent staining provided the most satisfactory results, as evidenced by the high contrast of bacterial morphology and appendage structures. However, after being suspended in NB and stained with PTA, bacteria often had too high contrast or poor staining, with electron-dense aggregates around the bacteria. These results suggest that suspension with concentrated organic aliquots including broth media before PTA staining could deteriorate image contrast, and should be used only in dilute form for visualizing bacterial morphology and appendage structures. Moreover the contrast enhancement of unstained bacteria by salt granules would be advantageous in demonstrating bacterial sorption of environmental particles like heavy metals, maintaining minimal contrast for cell imaging.

• 치과방사선
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• 제20권1호
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• pp.113-124
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• 1990

For the study of the influence of kilovoltage and exposure time on radiographic density and contrast, we measured radiographic density of aluminum step wedge which composed of contiguous 8 steps wedges of 2-16㎜ thickness with densitometer. Aluminum step wedge was radiographed on Kodak ultraspeed DF-58 and Ektaspeed EP-21 film with range of 60-90 kVp and 5-60 impulse and subject contrast of aluminum step wedge with constant radiographic density and image contrast percentage without radiographic density was evaluated. Then we evaluated the film quality of teeth and their surrounding structure according to the change of kVp and exposure time by score rating method. The obtained results were as follows: 1. Radiographic density was related to the change of kilovoltage, especially in increased exposure time. 2. With constant radiographic density, subject contrast of thin aluminum step wedges was greater in low kilovolt age than high kilovoltage, but kilovolt age had not great influence on subject contrast of thick aluminum step wedge. On the other hand, radiographic density difference between 2mm and 16mm aluminum step wedge was decreased according to in- creasing kilovoltage. 3. Without constant radiographic density, image contrast percentage was decreased with increasing kilovoltage, but was not related with the change of exposure time. 4. Radiographic contrast of teeth and their surrounding structure which was taken with the range of 60-90 kVp and 6-30 impulse had not great influence on film quality.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제22권1호
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• pp.7-15
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• 2016

Purpose: There are the number of color tactile walking surface indicators installed in Korea, because of indefinite regulation in blind and vision-impaired persons' tactile walking surface indicators. In case of yellow tactile walking surface indicators, it shows a deviation severe color. In this study, the researchers suggested color and brightness reference for helping blind and vision-impaired persons' walking through analyzing the color references of tactile walking surface indicators and the color luminance between tactile walking surface indicators and sidewalk currently used. Method: Reasonable luminance contrast criteria is suggested by examining ways of improving the recognition and recognition of objects according to color contrast visually impaired through literature review and analyzing standards of tactile walking surface indicators and the Europe, Japan and Australia of color and luminance contrast criteria. And by examining the color of the tactile walking surface indicators reported in Korea currently used to derive the problem presented by the luminance contrast in the reference and comparison. Finally, the visually impaired tactile walking surface indicators is set for color selection criteria for the recognition rate improves. Results: In order to improve the recognition rate to be tactile walking surface indicators of the contrast of the visually impaired and the environment than the color of the tactile walking surface indicators itself to secure always a certain level or more of brightness contrast values in the set of the color of the tactile walking surface indicators so important. Implication: In order to set the blind tactile walking surface indicators color recognition based on the verification of the real pedestrian based on the results presented in this paper it is required. It is to be understood as an element of the barrier free configuration for securing the walking pedestrian safety.

• 대한건축학회논문집:구조계
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• 제35권5호
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• pp.191-202
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• 2019

This study examines the effect of luminance contrast ratio of character on readability and visual fatigue during an hour-long reading session while using a tablet PC in ambient environments having low luminance limited to $25cd/m^2$. Experiments were conducted with four patterns of the tablet's luminance contrast ratio of characters, namely 1:2.5, 1:4.5, 1:6.5, and 1:8.5, in low ambient luminance of $9cd/m^2$ and $25cd/m^2$. The obtained results show that the characters can be easily read at the luminance contrast ratio of character of 1:8.5 under surface luminance of $25cd/m^2$. Visual fatigue was evaluated through a subjective survey of symptoms. Physical, psychological, and visual fatigue were observed at a surface luminance of $9cd/m^2$, whereas solely visual fatigue was felt at a surface luminance of $25cd/m^2$. By assessing the physical fatigue using the value, it has been found that smaller the luminance contrast ratio of character, greater is the CFF variation rate. Furthermore, readability is poor and visual fatigue can be observed when the surface luminance is lower than the ambient luminance. However, readability can be improved by increasing the luminance contrast ratio of character to a value of 1:8.5. Thus, in low luminance environments, luminance contrast ratio of characters can affect readability and fatigue. Consider providing the full form of "CFF" so that the acronym can be used unambiguously throughout the manuscript.

• Korean Journal of Radiology
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• 제22권6호
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• pp.951-958
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• 2021

Objective: To evaluate the usefulness of virtual monochromatic images (VMIs) obtained using dual-layer dual-energy CT (DL-DECT) for evaluating brain tumors. Materials and Methods: This retrospective study included 32 patients with brain tumors who had undergone non-contrast head CT using DL-DECT. Among them, 15 had glioblastoma (GBM), 7 had malignant lymphoma, 5 had high-grade glioma other than GBM, 3 had low-grade glioma, and 2 had metastatic tumors. Conventional polychromatic images and VMIs (40-200 keV at 10 keV intervals) were generated. We compared CT attenuation, image noise, contrast, and contrast-to-noise ratio (CNR) between tumor and white matter (WM) or grey matter (GM) between VMIs showing the highest CNR (optimized VMI) and conventional CT images using the paired t test. Two radiologists subjectively assessed the contrast, margin, noise, artifact, and diagnostic confidence of optimized VMIs and conventional images on a 4-point scale. Results: The image noise of VMIs at all energy levels tested was significantly lower than that of conventional CT images (p < 0.05). The 40-keV VMIs yielded the best CNR. Furthermore, both contrast and CNR between the tumor and WM were significantly higher in the 40 keV images than in the conventional CT images (p < 0.001); however, the contrast and CNR between tumor and GM were not significantly different (p = 0.47 and p = 0.31, respectively). The subjective scores assigned to contrast, margin, and diagnostic confidence were significantly higher for 40 keV images than for conventional CT images (p < 0.01). Conclusion: In head CT for patients with brain tumors, compared with conventional CT images, 40 keV VMIs from DL-DECT yielded superior tumor contrast and diagnostic confidence, especially for brain tumors located in the WM.

• 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.

• Journal of Cerebrovascular and Endovascular Neurosurgery
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• 제25권4호
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• pp.420-428
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• 2023

Objective: Intraprocedural rupture (IPR) is a fatal complication of endovascular coiling for cerebral aneurysms. We hypothesized that contrast leakage period may be related to poor clinical outcomes. This study aimed to retrospectively evaluate the relationship between clinical outcomes and contrast leakage period. Methods: Data from patients with cerebral aneurysms treated via endovascular coiling between January 2010 and October 2018 were retrospectively assessed. The enrolled patient's demographic data, the aneurysm related findings, endovascular treatment and IPR related findings, rescue treatment, and clinical outcome were analyzed. Results: In total, 2,859 cerebral aneurysms were treated using endovascular coiling during the study period, with IPR occurring in 18 (0.63 %). IPR occurred during initial frame coiling (n=4), coil packing (n=5), stent deployment (n=7), ballooning (n=1), and microcatheter removal after coiling (n=1). Tear sites included the dome (n=14) and neck (n=4). All IPRs were controlled and treated with coil packing, with or without stenting. Flow arrest of the proximal balloon was not observed. Temporary focal neurological deficits developed in two patients (11.1%). At clinical follow-up, 14 patients were classified as modified Rankin Scale (mRS) 0, three as mRS 2, and one as mRS 4. The mean contrast leakage period of IPR was 11.2 min (range: 1-31 min). Cerebral aneurysms with IPR were divided into late (n=9, mean time: 17.11 min) and early (n=9, mean time: 5.22 min) control groups based on the criteria of 10 min of contrast leakage period. No significant between-group differences regarding clinical outcomes were observed after IPR (p=1). Conclusions: In our series, all patients with IPR were controlled with further coil packing or stenting without proximal balloon occlusion within 31 min of contrast leakage. There was no difference in clinical outcomes when the long contrast leakage period group and short contrast leakage period group were compared.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.485-486
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• 2012