• 대한의용생체공학회:의공학회지
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• 제21권4호
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• pp.333-338
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• 2000

본 논문에서는 T1 강조영상, T2 강조 영상 그리고 PD의 영상의 특징을 상호 보완적으로 이용한 자동적인 영상 분할법을 제안한다. 제안한 분할 알고리듬은 3단계로 이루어지는데, 첫 단계에서는 PD 영상으로부터 대뇌 마스크를 획득한 후, T1과 T2, PD의 입력 영상에 대뇌 마스크를 씌워 각각의 대뇌 영상을 추출하고, 둘째 단계에서는 대뇌 내부 조직에 해당하는 두드러진 클러스터(outstanding cluster)를 3차원 클러스터들 중에서 선택한다. 3차원 클러스터는 최적스케일 영상(optimal scale image)으로 이루어지는 3차원 공간상에서 화소가 밀집된 봉우리들을 교집합해서 생성되는 클러스터로 결정한다. 최적스케일 영상은 각 2타원 히스토그램에 스케일 스페이스 필터링을 적용시키고 그래프(graph) 구조를 검색하여 2차원 히스토그램의 모양을 가장 잘 나타내는 봉우리(peak) 영상을 최적 스케일 영상으로 선택한다. 마지막 단계에서는 앞에서 찾은 두드러진 클러스터의 중심값을 FCM 알고리듬의 초기중심 값으로 두고, FCM 알고리듬을 이용하여 대뇌 영상을 분할한다. 제안한 분할 알고리듬은 정확한 클러스터의 중심값을 계산함으로 초기 값을 영향을 많이 받는 FCM 알고리듬의 단점을 보완하였고 다중 스펙트럼 영상의 특성을 조합하여 분할에 이용함으로 단일 스펙트럼 영상만을 이용하는 방법보다 향상된 결과를 얻을 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권3호
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• pp.962-975
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• 2020

The accurate segmentation of infant brain MR image into white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF) is very important for early studying of brain growing patterns and morphological changes in neurodevelopmental disorders. Because of inherent myelination and maturation process, the WM and GM of babies (between 6 and 9 months of age) exhibit similar intensity levels in both T1-weighted (T1w) and T2-weighted (T2w) MR images in the isointense phase, which makes brain tissue segmentation very difficult. We propose a deep network architecture based on U-Net, called Triple Residual Multiscale Fully Convolutional Network (TRMFCN), whose structure exists three gates of input and inserts two blocks: residual multiscale block and concatenate block. We solved some difficulties and completed the segmentation task with the model. Our model outperforms the U-Net and some cutting-edge deep networks based on U-Net in evaluation of WM, GM and CSF. The data set we used for training and testing comes from iSeg-2017 challenge (http://iseg2017.web.unc.edu).

• Journal of Korean Neurosurgical Society
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• 제45권2호
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• pp.99-102
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• 2009

Inflammatory pseudotumor is an uncommon lesion with unknown etiology characterized by sclerosing inflammation which clinically and radiographically mimics a neoplastic lesion. A 47-year-old man presented with sudden headache and dysarthria. Brain CT scan revealed a $2.6{\times}2.2\;cm$ sized, round, and hyperdense mass in the anterolateral wall of the left lateral ventricular trigone. On MR imaging studies, the mass showed low signal intensity in the wall of the trigone on T2-weighted image, central mixed (iso- and high-) signal intensity with peripheral low-signal intensity on T1-weighted image. Subtle staining of left choroid plexus with irregular shaped distal branch of anterior choroidal artery was found on the cerebral angiography. These findings suggested a small tumorous lesion originated from the left choroid plexus. During the hospital days, the mass manifested as repeated hemorrhages. The mass was successfully removed via left occipital transcortical approach. The histopathological report of the specimen was hemorrhage and fibrosis, with dense lymphoplasma cell infiltration, suggestive of an inflammatory pseudotumor.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.450-453
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• 2000

In this paper, an automated segmentation algorithm is proposed for MR brain images using T1-weighted, T2-weighted, and PD images complementarily. The proposed segmentation algorithm is composed of 3 steps. In the first step, cerebrum images are extracted by putting a cerebrum mask upon the three input images. In the second step, outstanding clusters that represent inner tissues of the cerebrum are chosen among 3-dimensional (3D) clusters. 3D clusters are determined by intersecting densely distributed parts of 2D histogram in the 3D space formed with three optimal scale images. Optimal scale image best describes the shape of densely distributed parts of pixels in 2D histogram. In the final step, cerebrum images are segmented using FCM algorithm with it’s initial centroid value as the outstanding cluster’s centroid value. The proposed segmentation algorithm complements the defect of FCM algorithm, being influenced upon initial centroid, by calculating cluster’s centroid accurately And also can get better segmentation results from the proposed segmentation algorithm with multi spectral analysis than the results of single spectral analysis.

• 한국임상수의학회지
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• 제34권5호
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• pp.377-380
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• 2017

An 8-year-old, shih-tzu female dog was referred due to neurological signs including paraparesis and back pain. On the complete blood count, hematologic analysis showed elevated leukocytosis. Serum biochemical analysis revealed elevated serum alkaline phosphatase concentration and C-reactive protein concentration. On the neurologic exam, the dog was suspected to have thoracolumbar myelopathy. On magnetic resonance imaging, there were masses within the spinal canal at L1-3 intervertebral disc space that were located dorsal to spinal cord. It was hyperintense on T1-, T2-weighted magnetic resonance images, Fluid-attenuated inversion recovery, and fat suppression images. The contrast-enhanced T1-weighted images showed no enhancement. The lesions were well circumscribed. The spinal cord was compressed and displaced ventrally by the mass. After removal of the masses via L1-L3 dorsal laminectomy, pyogranulomatous inflammation was confirmed by histopathological examination. Six months after surgery, the dog recovered uneventfully and remained fully ambulatory with no neurological deficits. This case demonstrates the utility of magnetic resonance imaging for the diagnosis of spinal canal pyogranulomatous inflammation.

• 한국산학기술학회논문지
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• 제16권7호
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• pp.4704-4710
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• 2015

본 연구는 가돌리늄 조영제의 T1 shortening effect를 이용하여 말초동맥으로 갈수록 신호강도가 낮아지는 위상영상의 단점을 근본적으로 개선함으로써 진단에 유용한 영상을 획득하고자 하였다. 연구기간은 2014년 10월부터 동년 12월까지 시행하였으며, 심장질환자를 제외한 AVM 환자 30명을 대상으로 하였다. 연구방법은 T1 shortening effect에 따른 신호강도의 차이를 알아보기 위해 가돌리늄 조영제 주입 전 후 자화강조영상을 획득한 다음, 위상영상을 비교평가 하였다. 연구결과, 가돌리늄 조영제 주입 전, 후 뇌실질 내 말초동맥의 신호강도는 가돌리늄 조영제 주입 후가 주입 전에 비해 전두엽 19.45%, 측두엽 23.09%, 두정엽 18.82%, 후두엽 25.45%, 소뇌 20.93%로 증가 하였고 통계적으로 유의하였다. 그러므로 위상영상 획득 시 가돌리늄 조영제의 T1 shortening effect를 이용하면 위상영상의 단점을 보완할 수 있어 진단 및 치료에 유용한 영상을 획득할 수 있으리라 사료된다.

• 대한영상의학회지
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• 제84권1호
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• pp.226-239
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• 2023

목적 뇌동정맥루(arteriovenous fistula; 이하 AVF), 뇌동정맥기형(arteriovenous malformation; 이하 AVM), 경동맥해면정맥동루(carotid-cavernous sinus fistula; 이하 CCF) 등 뇌동정맥단락을 진단하는 데 있어서, T2 강조영상(T2-weighted imaging; 이하 T2WI)과 자화율 강조영상(susceptibility-weighted imaging; 이하 SWI)의 민감도를 비교하고, 단일 에코(single-echo) SWI(이하 s-SWI)와 다중 에코(multi-echo) SWI (이하 m-SWI)의 전반적인 영상 질을 비교하고자 하였다. 대상과 방법 2016년부터 2021년까지 뇌혈관조영술로 입증된 뇌동정맥단락을 조사하였다. 뇌동정맥단락에 대한 T2WI와 SWI의 민감도를 McNemar's Test를 이용하여 비교하였다. s-SWI와 m-SWI의 영상 질을 나쁨, 보통, 좋음으로 분류하고 Fisher's exact test를 이용하여 그 비율을 비교하였다. 결과 총 24명의 환자(중위 연령: 61세, 여성: 12명, 남성: 12명)가 연구에 포함되었다. 그중 4명은 s-SWI와 m-SWI 두 가지의 SWI로, 나머지 20명은 이 중 한 가지의 SWI로 검사하였다. 10명은 AVF, 11명은 AVM, 3명은 CCF로 진단되었고, 이와 같은 뇌동정맥단락에 대해, SWI는 T2WI 보다 유의하게 높은 민감도를 보였다(82.1% vs. 53.6%, p = 0.013). m-SWI는 s-SWI 보다 좋은 영상 질의 비율이 유의하게 높았다(83.3% vs. 25.0%, p = 0.009). 결론 SWI는 T2WI 보다 뇌동정맥단락을 더 민감하게 진단해 낼 수 있었으며, m-SWI는 s-SWI보다 혈관질환을 평가하는데 더 좋은 영상 질을 보였다.

• 한국임상수의학회지
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• 제31권5호
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• pp.445-448
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• 2014

7년령 수컷 말라뮤트 견이 정기적인 치과진료를 목적으로 내원하였다. 신체검사 상에서 뒷다리의 운동 실조가 확인되었으며, 우측 뒷다리의 고유 자세반응이 미약하게 지연되었다. 감별진단을 위한 MRI 검사에서, 허리뼈 1번과 2번 사이 척수강에 경막외 낭종이 확인되었다. 낭종은 디스크 바로 등쪽에서 척수실질 배쪽을 등쪽으로 심하게 압박하고 있었으며, T1 저신호, T2 고신호 및 낭종 벽을 따라 조영증강이 확인되었다. 편측성 추궁절제술을 통해 낭종을 제거하였고, 조직검사 결과 낭종의 벽은 섬유소 및 섬유아세포가 혼재되어 있었으며 일부분에서 호염성 디스크 물질이 확인되어 디스크 낭종으로 진단하였다. 환자는 수술 후 신경증상은 정상적으로 회복하였으며, 6개월 후 신체검사에서 정상적인 보행 이 관찰되었다.

• Investigative Magnetic Resonance Imaging
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• 제22권1호
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• pp.1-9
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• 2018

Purpose: This study was designed to optimize the flip angle (FA) and scan timing of the hepatobiliary phase (HBP) using the 3D T1-weighted, gradient-echo (GRE) imaging with controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique on gadoxetic acid-enhanced 3T liver MR imaging. Materials and Methods: Sixty-two patients who underwent gadoxetic acid-enhanced 3T liver MR imaging were included in this study. Four 3D T1-weighted GRE imaging studies using the CAIPIRINHA technique and FAs of $9^{\circ}$ and $13^{\circ}$ were acquired during HBP at 15 and 20 min after intravenous injection of gadoxetic acid. Two abdominal radiologists, who were blinded to the FA and the timing of image acquisition, assessed the sharpness of liver edge, hepatic vessel clarity, lesion conspicuity, artifact severity, and overall image quality using a five-point scale. Quantitative analysis was performed by another radiologist to estimate the relative liver enhancement (RLE) and the signal-to-noise ratio (SNR). Statistical analyses were performed using the Wilcoxon signed rank test and one-way analysis of variance. Results: The scores of the HBP with an FA of $13^{\circ}$ during the same delayed time were significantly higher than those of the HBP with an FA of $9^{\circ}$ in all the assessment items (P < 0.01). In terms of the delay time, images at the same FA obtained with a 20-min-HBP showed better quality than those obtained with a 15-min-HBP. There was no significant difference in qualitative scores between the 20-min-HBP and the 15-min-HBP images in the non-liver cirrhosis (LC) group except for the hepatic vessel clarity score with $9^{\circ}$ FA. In the quantitative analysis, a statistically significant difference was found in the degree of RLE in the four HBP images (P = 0.012). However, in the subgroup analysis, no significant difference in RLE was found in the four HBP images in either the LC or the non-LC groups. The SNR did not differ significantly in the four HBP images. In the subgroup analysis, 20-min-HBP imaging with a $13^{\circ}$ FA showed the highest SNR value in the LC-group, whereas 15-min-HBP imaging with a $13^{\circ}$ FA showed the best value of SNR in the non-LC group. Conclusion: The use of a moderately high FA improves the image quality and lesion conspicuity on 3D, T1-weighted GRE imaging using the CAIPIRINHA technique on gadoxetic acid, 3T liver MR imaging. In patients with normal liver function, the 15-min-HBP with a $13^{\circ}$ FA represents a feasible option without a significant decrease in image quality.

• Korean Journal of Radiology
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• 제21권1호
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• pp.77-87
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• 2020

Objective: To assess the feasibility of simultaneous multislice-accelerated diffusion-weighted imaging (SMS-DWI) of the rectum in comparison with conventional DWI (C-DWI) in rectal cancer patients. Materials and Methods: This study included 65 patients with initially-diagnosed rectal cancer. All patients underwent C-DWI and SMS-DWI with acceleration factors of 2 and 3 (SMS2-DWI and SMS3-DWI, respectively) using a 3T scanner. Acquisition times of the three DWI sequences were measured. Image quality in the three DWI sequences was reviewed by two independent radiologists using a 4-point Likert scale and subsequently compared using the Friedman test. Apparent diffusion coefficient (ADC) values for rectal cancer and the normal rectal wall were compared among the three sequences using repeated measures analysis of variance. Results: Acquisition times using C-DWI, SMS2-DWI, and SMS3-DWI were 173 seconds, 107 seconds, (38.2% shorter than C-DWI), and 77 seconds (55.5% shorter than C-DWI), respectively. For all image quality parameters other than distortion (margin sharpness, artifact, lesion conspicuity, and overall image quality), C-DWI and SMS2-DWI yielded better results than did SMS3-DWI (Ps < 0.001), with no significant differences observed between C-DWI and SMS2-DWI (Ps ≥ 0.054). ADC values of rectal cancer (p = 0.943) and normal rectal wall (p = 0.360) were not significantly different among C-DWI, SMS2-DWI, and SMS3-DWI. Conclusion: SMS-DWI using an acceleration factor of 2 is feasible for rectal MRI resulting in substantial reductions in acquisition time while maintaining diagnostic image quality and similar ADC values to those of C-DWI.