• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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• pp.104-104
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• 2001

Purpose： In this study, we investigated the possible motor pathways of hemiplegic stroke patients usin combined TMS and BOLD fMRI approach and evaluated the correlation between TMS a fMRI methods. Method： Four subjects, who demonstrated left hemiplegia after stroke, are included. TMS was performed using a Dantec Mag2 stimulator (Dantec Company, USA) in single puls mode with figure eight-shaped coil. Following TMS localization, The BOLD T2＊-weight images were acquired with echo planar imaging sequence (TR = 1.2 sec, TE = 60 msec, and flip angle = 90). Motor activation was studied by means of a repetitive fing flexion-extension task. The stimulation protocol comprised 10 cycles of alternating activati and rest (10 images per cycle). Total 60 cycles were performed and each cycle take abou 1.5 sec. The resulting images were then analyzed with STIMULATE (CMRR, U, o Minnesota) to generate functional maps using a student t-test (p < 0.0005) and cluste analysis.

• Journal of Acupuncture Research
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• 제21권6호
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• pp.177-186
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• 2004

Introduction : Recent studies Suggested that there is a strong correlation between acupuncture stimulation and its related cortical activation. Anther study showed that either positive or negative BOLD effects could be observed depending on anatomical structure in acupuncture stimulation. In ttis study, we investigated a new acupoint $KI_6$ (照海), which was known as motor-related acupoint and obtained an evidence that the stimulation of $KI_6$ resulted in either negative or positive BOLD response to stimulation. Methods & Results : 1. Subjects and paradigms : Two separate stimulation paradigms were performed on five healthy (aged 22-23 yrs) in this study. First, the paradigm of acupuncture stimulation was that the acupuncture needle was inserted in acupoints $KI_6$, which is located in lateral side of the foot and then continuously twisted(補瀉를 除外한 捻轉法) for 70 seconds for 10 cycles of activation. During rest period (70 seconds), the needle was completed removed from acupoint. Total 60 cycles were performed and 10 images were obtained per cycle. Second, nonacupoint was randomly selected and the same paradigm was performed as acupoint stimulation. The stimulation protocol comprised 10 cycles of alternating. activation and rest (10 images per cycle). Total 60 cycles were performed and each cycle take about 1.5 sec for motor task. Subjects take an at least 15 minutes break before starting anther paradigm. 2. fMRI mapping : Multi-slice functional images were obtained on a 1.5T Magnetom Vision MRI scanner (Simens Medical, Erlangen, Germany) equipped with high performance whole-body gradients. The BOLD T2 * - weighted images were acquired with acho planar imaging sequence (TR = 1.2 sec, TE = 60 msec, and flip angle = $90_{\circ}$). The other sequence parameter are : FOV = 210 mm, matrix=$64{\times}128$ or $64{\times}64$, slice number=10 and slice thickness = 5 or 8 mm. the anatomic images were obtained with Spin-echo T1-weighted images. The resulting images were then anaiyzed with STIMULATE (CMRR, U. of Minnesota) to generate functional maps using a student T-test (p < 0.005) and cluster analysis. Both positive and negative response were evaluated. Conclusions : We have observed the activation of the motor cortex by stimulating motor-related acupoint ($KI_6$). Among five subjects, negative BOLD response was shown in four and positive response in one. All subjects showed positive response to conventional finger flexion-extension task. To understand the detailed mechanisms of correlation between acupuncture stimulation and BOLD fMRI changes and two typs of response, further study strongly required.

• 한국임상수의학회지
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• 제25권3호
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• pp.176-181
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• 2008

Fluid accumulation within the tympanic bulla is an important diagnostic indicator of canine otitis media although its identification can be a challenge using currently available imaging techniques. The purpose of this study was to compare radiography, computed tomography (CT) and magnetic resonance imaging (MRI) in the identification of fluid accumulation within canine tympanic bulla. Unilateral tympanic bulla in 10 beagles were experimentally filled with blood or saline. Quantitative analysis of CT images were obtained by using Hounsfield unit (HU). MR signal intensity was obtained by using region of interesting (ROI) and compared with those of gray matter. On the CT image, the presence of blood or saline produced a fluid opacity occupying the tympanic bulla. On the MR image, the appearance of blood in the tympanic bulla was isointense in T1-weighted images and hyperintense in T2-weighted images. However, the appearance of saline in the tympanic bulla was hypointense in T1-weighted images and hyperintense in T2-weighted images. This study suggest that CT and MR imaging are useful methods for detection and differentiation of fluid in canine tympanic bulla.

• Investigative Magnetic Resonance Imaging
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• 제19권1호
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• pp.19-30
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• 2015

Purpose: A new compressed sensing technique by iterative truncation of small transformed coefficients (ITSC) is proposed for fast cardiac CINE MRI. Materials and Methods: The proposed reconstruction is composed of two processes: truncation of the small transformed coefficients in the r-f domain, and restoration of the measured data in the k-t domain. The two processes are sequentially applied iteratively until the reconstructed images converge, with the assumption that the cardiac CINE images are inherently sparse in the r-f domain. A novel sampling strategy to reduce the normalized mean square error of the reconstructed images is proposed. Results: The technique shows the least normalized mean square error among the four methods under comparison (zero filling, view sharing, k-t FOCUSS, and ITSC). Application of ITSC for multi-slice cardiac CINE imaging was tested with the number of slices of 2 to 8 in a single breath-hold, to demonstrate the clinical usefulness of the technique. Conclusion: Reconstructed images with the compression factors of 3-4 appear very close to the images without compression. Furthermore the proposed algorithm is computationally efficient and is stable without using matrix inversion during the reconstruction.

• 대한의용생체공학회:의공학회지
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• 제27권3호
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• pp.110-116
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• 2006

Finite element method (FEM) provides several advantages over other numerical methods such as boundary element method, since it allows truly volumetric analysis and incorporation of realistic electrical conductivity values. Finite element mesh generation is the first requirement in such in FEM to represent the volumetric domain of interest with numerous finite elements accurately. However, conventional mesh generators and approaches offered by commercial packages do not generate meshes that are content-adaptive to the contents of given images. In this paper, we present software that has been implemented to generate content-adaptive finite element meshes (cMESHes) based on the contents of MR images. The software offers various computational tools for cMESH generation from multi-slice MR images. The software named as the Content-adaptive FE Mesh Generation Toolbox runs under the commercially available technical computation software called Matlab. The major routines in the toolbox include anisotropic filtering of MR images, feature map generation, content-adaptive node generation, Delaunay tessellation, and MRI segmentation for the head conductivity modeling. The presented tools should be useful to researchers who wish to generate efficient mesh models from a set of MR images. The toolbox is available upon request made to the Functional and Metabolic Imaging Center or Bio-imaging Laboratory at Kyung Hee University in Korea.

• Journal of Korean Neurosurgical Society
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• 제50권4호
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• pp.388-391
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• 2011

A lesion that is hyperintense on diffusion-weighted imaging (DWI) and hypointense on the apparent diffusion coefficient (ADC) map is a characteristic magnetic resonance imaging (MRI) finding in acute ischemic infarction. In some cases, however, these findings can persist for a few months after infarct onset. It is thought that these finding reflect the different evolution speeds of the infarcted tissue. We report a patient with a right middle cerebral artery territory infarction with persistent hyperintensity on DWI and hypointensity on the ADC map for over 8 months. To our knowledge, this is the most persistent case of hyperintensity lesion on DWI and the serial MRI images of this patient provide important information on the evolution of infarcted tissue.

• 응용통계연구
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• 제16권2호
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• pp.305-319
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• 2003

본 연구에서는 바이어스 필드에 의해 왜곡된 MRI 영상에 대한 분할을 위해 확장된 EM 알고리즘을 기반으로 한 통계적 접근법을 제시한다. 영상의 명암값을 자료로 하는 분할기법들은 고주파 성분의 잡음 뿐만 아니라 영상을 불균질하게 만드는 바이어스 필드라는 저주파 성분의 왜곡에 특히 취약하다. 이 문제를 해결하기 위해 본 논문에서는 잡음을 효과적으로 제어하기 위해 마코프랜덤필드가 적용된 정규혼합모형을 고려하며, 효과적인 바이어스 필드의 보정을 위해 페널티-우도를 도입하여 추정하는 방법으로 고안되었다.

• Imaging Science in Dentistry
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• 제43권4호
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• pp.245-251
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• 2013

Purpose: This study was performed to evaluate the relationship between anterior disc displacement and effusion in temporomandibular disorder (TMD) patients using magnetic resonance imaging (MRI). Materials and Methods: The study subjects included 253 TMD patients. MRI examinations were performed using a 1.5 T MRI scanner. T1- and T2-weighted images with para-sagittal and para-coronal images were obtained. According to the MRI findings, temporomandibular joint (TMJ) disc positions were divided into 3 subgroups: normal, anterior disc displacement with reduction (DWR), and anterior disc displacement without reduction (DWOR). The cases of effusion were divided into 4 groups: normal, mild (E1), moderate (E2), and marked effusion (E3). Statistical analysis was made by the Fisher's exact test using SPSS (version 12.0, SPSS Inc., Chicago, IL, USA). Results: The subjects consisted of 62 males and 191 females with a mean age of 28.5 years. Of the 253 patients, T1- and T2-weighted images revealed 34 (13.4%) normal, DWR in 103 (40.7%), and DWOR in 116 (45.9%) on the right side and 37 (14.6%) normal, DWR in 94 (37.2%), and DWOR in 122 (48.2%) joints on the left side. Also, T2-images revealed 82 (32.4%) normal, 78 (30.8%) E1, 51 (20.2%) E2, and 42 (16.6%) E3 joints on the right side and 79 (31.2%) normal, 85 (33.6%) E1, 57 (22.5%) E2, and 32 (12.7%) E3 on the left side. There was no difference between the right and left side. Conclusion: Anterior disc displacement was not related to the MRI findings of effusion in TMD patients (P>0.05).

• 대한방사선기술학회지:방사선기술과학
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• 제42권2호
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• pp.113-117
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• 2019

The purpose of this study was to investigate the FA value which can produce the best T2-weighted images by measuring the signal intensity and noise according to the FA value change in the brain image and the abdominal image of the mouse using micro-MRI. Brain imaging and abdominal imaging of BALB / C mice weighing 20g were performed using 4.7T (Bruker BioSpin MRI GmbH) micro-MRI equipment, Turbo RARE-T2 (spin echo-T2) images were scanned at TR 3500 msec and TE 36 msec. The changes of the FA values were $60^{\circ}$, $80^{\circ}$, $100^{\circ}$, $120^{\circ}$, $140^{\circ}$, $160^{\circ}$ and $180^{\circ}$. We measured signal intensity according to FA values of ventricle and thalamus in brain imaging, The signal intensity of kidney and muscle around the kidney was measured in abdominal images. To obtain SNR and CNR, we measured the background signals of two different parts, not the tissue. In the brain (thalamus) image, the signal intensity of FA $100^{\circ}$ was 7,433 and SNR (6.49) was the highest. In the abdominal (kidney) image, the signal intensity was highest at 16,523 when FA was $120^{\circ}$, and the highest SNR was 8.54 when FA was $140^{\circ}$. The CNR value of the brain image was 1.38 at FA $60^{\circ}$ and gradually increased to 8.29 at FA $180^{\circ}$. The CNR value of the muscle adjacent to the kidney gradually increased from 2.36 when the FA value was $60^{\circ}$ and the highest value was 4,57 at the FA value $180^{\circ}$.

• 한국멀티미디어학회논문지
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• 제24권8호
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• pp.979-987
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• 2021

Multiple Sclerosis (MS) can be early diagnosed by detecting lesions in brain magnetic resonance images (MRI). Unsupervised anomaly detection methods based on autoencoder have been recently proposed for automated detection of MS lesions. However, these autoencoder-based methods were developed only for 2D images (e.g. 2D cross-sectional slices) of MRI, so do not utilize the full 3D information of MRI. In this paper, therefore, we propose a novel 3D autoencoder-based framework for detection of the lesion volume of MS in MRI. We first define a 3D convolutional neural network (CNN) for full MRI volumes, and build each encoder and decoder layer of the 3D autoencoder based on 3D CNN. We also add a skip connection between the encoder and decoder layer for effective data reconstruction. In the experimental results, we compare the 3D autoencoder-based method with the 2D autoencoder models using the training datasets of 80 healthy subjects from the Human Connectome Project (HCP) and the testing datasets of 25 MS patients from the Longitudinal multiple sclerosis lesion segmentation challenge, and show that the proposed method achieves superior performance in prediction of MS lesion by up to 15%.