• Proceedings of the KSMRM Conference
• /
• 1999.11a
• /
• pp.92-92
• /
• 1999

• Proceedings of the KSMRM Conference
• /
• 2006.11a
• /
• pp.44-44
• /
• 2006

• Proceedings of the KSMRM Conference
• /
• 2001.11a
• /
• pp.104-104
• /
• 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.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.50 no.12
• /
• pp.587-591
• /
• 2001

This paper describes the general and efficient design method of an axial and a radial shim coils to correct field impurities of various harmonic orders in the imaging volume of Magnetic Resonance Imaging magnet. Shim coils are optimized by BCLSF subroutine of IMSL, which is the well-known commercial package for optimization, aiming at maximizing the magnitude of the desired field component as well as minimizing other field components. In order to evaluate their effect, the developed method was applied to the MRI magnet constructed in KERI.

• Proceedings of the Korea Contents Association Conference
• /
• 2013.05a
• /
• pp.213-214
• /
• 2013

본 연구는 밀폐된 공간과 다른 검사보다 시간이 오래 걸리는 자기공영상(MRI)검사 장비에서 환자와의 접촉이 많은 Head coil, Block, 밀폐된 공간인 Bore 등의 세균오염도를 측정 및 세균의 종류를 파악하고, 설문을 통하여 감염관리 실태를 파악하고 자기공명영상(MRI)장비의 소독 상태를 파악함으로써 환자의 병원감염에 대한 인식의 개선과 소독의 중요성을 제시하고자 한다.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.12
• /
• pp.2019-2022
• /
• 2016

In the presence of an electrically conducting medical lead, radio frequency (RF) coils in magnetic resonance imaging (MRI) systems may concentrate the RF energy and cause tissue heating near the lead. A novel design for a medical lead to reduce this heating by introducing pins in the lead is presented. Peak 10 g specific absorption rate (SAR) in heart tissue, an indicator of heating, was calculated and compared for both conventional (Medtronic) lead design and our proposed design. Remcom XFdtd software was used to calculate the peak SAR distribution in a realistic model of the human body. The model contained a medical lead that was exposed to RF magnetic fields at 64 MHz (1.5 T), 128 MHz (3 T) and 300 MHz (7 T) using a model of an MR birdcage body coil. The proposed design of adding pins to the medical lead can significantly reduce the heating from different MRI systems.

• Journal of Institute of Control, Robotics and Systems
• /
• v.8 no.2
• /
• pp.97-103
• /
• 2002

This paper deals with a PWM(Pulse Width Modulation) current amplifier using digital controller in order to generate a gradient magnetic field far the MRI(Magnetic Resonance Image) system. Because of tolerance of discrete devices, it is difficult to set accurate values of the control parameters and to make an analog-controlling circuit. However, using digital controller, it is possible to set exact control parameters and to adopt a modern control techniques. It is shown that the digital controller will highly enhance the output current response and it will improve the quality of the MRI.

• Journal of radiological science and technology
• /
• v.44 no.6
• /
• pp.635-643
• /
• 2021

The results of empirical researches on the diagnosis of lung cancer are insufficient, so it is limited to objectively judge the clinical possibility and utilization according to the accuracy of diagnosis. Thus, this study retrospectively analyzed the lung cancer diagnostic performance of PET-MRI (Positron Emission Tomography-Magnetic Resonance Imaging) by using the decision matrix. This study selected and experimented total 165 patients who received both hematological CEA (Carcinoembryonic Antigen) test and hybrid PET-MRI (¹⁸F-FDG, 5.18 MBq/kg / Body TIM coil. VIVE-Dixon). After setting up the result of CEA (positive:>4 ㎍/ℓ. negative:<2.5㎍/ℓ) as golden data, the lung cancer was found in the image of PET-MRI, and then the SUV_max (positive:>4, negative:<1.5) was measured, and then evaluated the correlation and significance of results of relative diagnostic performance of PET-MRI compared to CEA through the statistical verification (t-test, P>0.05). Through this, the PET-MRI was analyzed as 96.29% of sensitivity, 95.23% of specificity, 3.70% of false negative rate, 4.76% of false positive rate, and 95.75% of accuracy. The false negative rate was 1.06% lower than the false positive rate. The PET-MRI that significant accuracy of diagnosis through high sensitivity and specificity, and low false negative rate and false positive rate of lung cancer, could acquire the fusion image of specialized soft tissue by combining the radio-pharmaceuticals with various sequences, so its clinical value and usefulness are regarded as latently sufficient.

• Proceedings of the KSMRM Conference
• /
• 2001.11a
• /
• pp.176-176
• /
• 2001

목적： 기존의 역수신코일(inside-out receiver coil)로 관벽의 MR 영상을 얻을 때 영상영역이 좁고 수신감도가 불균일한 단점을 보완하면서 신호대 잡음비(S/N ratio)도 높일 수 있는 회전자계역수 신코일(quadratic inside-out receiver coil)의 개발을 목적으로 한다. 대상 및 방법： 8극형코일, 선형자계수신코일, 회전자계수신코일에 대하여 컴퓨터 모의실험으로 영상영역 및 감도의 균일성을 비교하였다. 회전자계수신코일은 안장 모양을 한 두 개의 선형자계코일이 서로 간섭이 일어나지 않도록 수직 방향으로 배열된 구조를 갖도록 하였다. 지름 3 cm 크기로 각 코일을 제작하였으며 지름 20 cm의 원통 중앙에 내경 4 cm의 관이 있는 팬텀을 만들어 MnC1$_2$를 섞은 물을 채운 다음 1.5T 초전도 MRI 장치와 0.3T 영구자석 MRI 장치에서 팬텀의 관벽 영상을 얻었다. 본 실험을 시행한 1.5T 장치의 구조 때문에 회전자계코일의 두 안장코일을 결합하는 회로를 제작하여 사용하였고 0.3T에서는 장치에 내장된 결합회로를 사용하였다. 또한 포르말린 용액에 보관된 소의 대장 조직 단면 영상을 FOV 10-12 cm로 얻어 회전자 계안장코일의 성능을 평가하였다.

• Investigative Magnetic Resonance Imaging
• /
• v.18 no.2
• /
• pp.107-119
• /
• 2014

Purpose : To efficiently evaluate phased array coil performance using a software tool box with which we can make visual comparison of the sensitivity of every coil element between the real experiment and EM simulation. Materials and Methods: We have developed a $C^{{+}{+}}$- and MATLAB-based software tool called Phased Array Coil Evaluator (PACE). PACE has the following functions: Building 3D models of the coil elements, importing the FDTD simulation results, and visualizing the coil sensitivity of each coil element on the ordinary Cartesian coordinate and the relative coil position coordinate. To build a 3D model of the phased array coil, we used an electromagnetic 3D tracker in a stylus form. After making the 3D model, we imported the 3D model into the FDTD electromagnetic field simulation tool. Results: An accurate comparison between the coil sensitivity simulation and real experiment on the tool box platform has been made through fine matching of the simulation and real experiment with aids of the 3D tracker. In the simulation and experiment, we used a 36-channel helmet-style phased array coil. At the 3D MRI data acquisition using the spoiled gradient echo sequence, we used the uniform cylindrical phantom that had the same geometry as the one in the FDTD simulation. In the tool box, we can conveniently choose the coil element of interest and we can compare the coil sensitivities element-by-element of the phased array coil. Conclusion: We expect the tool box can be greatly used for developing phased array coils of new geometry or for periodic maintenance of phased array coils in a more accurate and consistent manner.