• Journal of the Korean Society of Radiology
• /
• v.9 no.5
• /
• pp.307-314
• /
• 2015

This study was conducted in reducing the involuntary motion artifacts because of lungs and heart movements as well as the aliasing artifacts generated during the use of the reduced-FOV EPI technique while performing breast MRI. Performed on a total of 38 obesity female subjects who visited the clinic for pre-examination before surgery within the period from August 1 to November 30, 2014. The 3.0T MRI scanner equipped with a breast scanning coil. Qualitative and quantitative analyses were each used for the evaluation of the acquired images while an Paired T-test and Wilcoxon rank test were performed to check the statistical significance. The variation ratio rose by 15.69% with the additional application of a pre-saturation pulse in the lesion, by 13.72% near the lesion, and 20.63% in the fat and the contrast-to-noise ratio rose by 10.58% in and near the lesion and by 12.03% in the lesion and fat, respectively. there were increases of 22.05% and 21.42% at 0 and 1000 respectively in qulitative evaluation and growth of 16.10% in apparent diffusion coefficient. it showed a statistically significant result(p<0.05) in signal to noise ratio, contrast to noise ratio, diffusion slope coefficient and apparent diffusion coefficient. The involuntary movements artifacts that occur in the phase encoding direction and the aliasing artifacts are considered to be reduced to obtain the best image in the additional use of the pre-saturation pulse as DWI is acquired.

• Proceedings of the KSMRM Conference
• /
• 1999.11a
• /
• pp.80-80
• /
• 1999

• The KIPS Transactions:PartB
• /
• v.13B no.2 s.105
• /
• pp.77-82
• /
• 2006

Digital halftoning is the technique to obtain a bilevel-toned image from continuous-toned image. Among halftoning methods, the error diffusion method gives better subjective quality than other halftoning ones. But it also makes edges of objects blurred. To overcome the defect, we proposes the modified error diffusion to enhance the edges using the property that human vision perceives the local average luminance and doesn't perceive a little variation of the spatial variation. The proposed method computes a spatialactivity, which is the difference between a pixel luminance and the average of its $3{\times}3$ neighborhood pixels' Iuminance weighted according to the spatial positioning. The system also usesof edge enhancement (IEE), which is computed from the normalized spatial activitymultiplied by the average luminance. The IEE is added to the quantizer's input pixel and feeds into the halftoning quantizer. The quantizer produces the halftone image having the enhanced edge. The computer experimental results show that the proposed method produces clearer bilevel-toned images than conventional methodsand the edge of objects is preserved well. Also the performance of the preposed method is improved, compared with that of the conventional method by measuring the edge correlation and the local average accordance at some ranges of viewing distance.

• Journal of the Korean Society of Radiology
• /
• v.82 no.4
• /
• pp.953-958
• /
• 2021

High-altitude cerebral edema (HACE) is a potentially fatal neurological syndrome that develops in persons traveling to a high altitude. We report the case of a 49-year-old male who had traveled to a high altitude, and lost consciousness for a few hours. Susceptibility-weighted images revealed multiple, fine black pepper like microbleeds along the corpus callosum with several microbleeds in the left frontal and parietal subcortical white matter. The T2-weighted images did not show any abnormal signal intensities along the corpus callosum. The diffusion-weighted images revealed small nodular high signal intensities in the basal ganglia. This report describes the atypical radiologic findings of HACE showing multiple microbleeds along the corpus callosum, without abnormal high-signal intensity on T2-weighted images.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
• /
• 2006.05a
• /
• pp.73-77
• /
• 2006

제 3차 국가 GIS 기본 계획의 목적은 국가지리정보체계의 원활한 구축 및 지리정보 활용촉진으로 기존의 구가 GIS 구축의 양적 확산에서 질적 심화를 도모하고 있다. 고해상도 위성영상이 다양한 분야에서 활발하게 이용하게 됨에 따라 지형자료의 더 정확한 경계검출에 대한 필요성이 대두되고 있다. 위성영상을 이용한 도로 경계 검출은 교통정보시스템을 포함한 도로계획, 도시계획 등의 GIS 응용을 위한 필수 연구로 인식하고 있다. 본 연구는 IKONOS 영상에서 도로 경계 검출을 위한 고주파 와 저주파 필터링 비교분석에 관한 연구이다. 분석결과 저주파 필터링과 고주파 필터링은 입력영상의 경계부분에서 영상을 선택적으로 강조할 수 있었다. 저주파 필터링과 같은 영상강화 기법에서는 추출 가능한 경계부의 위치를 변화시키거나 영상의 화소값이 전체영상을 대상으로 변화시켜 비교적 도로 폭이 넓은 경우 효과적이었다. 고주파 필터링은 세부적인 영상정보를 선택적으로 강조할 수 있었다.

• Proceedings of the KSMRM Conference
• /
• 1999.11a
• /
• pp.75-75
• /
• 1999

• Proceedings of the Korea Contents Association Conference
• /
• 2018.05a
• /
• pp.431-432
• /
• 2018

• Proceedings of the Korea Contents Association Conference
• /
• 2018.05a
• /
• pp.433-434
• /
• 2018

• Proceedings of the Korea Contents Association Conference
• /
• 2011.05a
• /
• pp.201-202
• /
• 2011

본 연구에는 7.0T 동물용 자기공명영상장치를 이용하여 인간의 췌장암 세포인 CFPAC-1를 이종 이식한 쥐에서 자기공명영상을 획득하여 최적화된 검사 Protocol을 정립하며, 동물 실험에서 밝혀진 종양특성과 확산강조영상과의 비교 분석을 해보고 현성확산계수 영상이 췌장암 이종이식 모형의 종양 세포 내부 구조에 관하여 어떠한 정보를 제공 할 수 있는지 알아보고자 한다. 13마리의 쥐의 26개의 종양을 전형적으로 주입 후에 2~4주 뒤에 직경이 5~10mm가 되었을 때 imaged 하였으며, pathologic specimenm을 위해 sacrificed 하였다. isofluoran gas anesthesia를 이용하여 동물 마취 하였다. 사용된 장비로는 small-animal MR images (7.0-T)를 (Bruker BioSpin GmbH, Rheinstetten, Germany)이용하여 Fast T2-weighted 와 single-shot EPI DW image를 얻었다. 종양은 H&E 염색과 CD31와 VEGF에 대한 면역조직학 염색을 하여 종양의 cellularity와 microvessel density(MVD), 종양 내 괴사 정도를 평가하였다. CFPAC-1의 현성확산계수값은 $0.7327{\pm}0.1075{\pm}10^{-3}mm2/s$이였으며, 현성확산계수는 종양내 괴사 정도와 연관성을 보였다(R = 0.7417, p = 0.0001) 이처럼 현성확산계수는 종양 내 괴사 정도 등의 현미경적구조변화를 반영하는 대리인자로 사용될 수 있음을 확인하였다.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.42 no.3 s.303
• /
• pp.107-114
• /
• 2005

Edge enhanced image is needed for processing images for special purpose such as a circuit diagram or a design composed of lines. Error diffusion halftoning, among digital halftoning methods to represent a continuous grayscale image for the binary output device such as printers, facsimiles, LCD televisions and etc. also makes edges of objects blurred. This paper proposes the method to enhance the edge of a binary image for the binary output device as well as a circuit diagram or a design. Based on that the human eyes perceive the local average luminance rather than the pixel's luminance itself, the proposed system uses a local activitymeasure (LAM), which is the difference between a pixel luminance and the average of its $3{\times}3$ neighborhood pixels' luminances weighted according to the spatial positioning. The system also usesinformation of edge enhancement(IEE), which is computed from the LAM multiplied by the average luminance. The IEE is added to the quantizer's input pixel and feeds into the halftoning quantizer. The quantizer produces the halftone image having the enhanced edge. The simulation results show that the proposed method produces more fine halftoning images than conventional methods due to the enhanced edges. Also the performance of the proposed method is compared with that of the conventional method by measuring the edge correlation and the local average accordance over a range of viewing distances.