자기공명영상장치(MRI) 자장세기에 따른 MRI 품질관리 영상검사의 개별항목점수 실태조사

조현혜,백상현,황지영,최원찬,심종훈 대한영상의학회 2012 대한영상의학회지 Vol.67 No.2

Purpose: The purpose of this study is to survey the MRI used in Korea according to the magnetic field strength (MFS), in order to evaluate the failure rate of the MRI quality assurance test, and to analyze the scores of the subsection for phantom and clinical image tests according to MFS. Materials and Methods: For quality assurance test in Korea from Jan 2009 to Dec 2009, 279 MRI were included in this study. The number of MRI was based according to MFS, the type of hospital, production year, and whether or not new or used equipment was from the Korea Institute Accreditation of Medical Image database. The rates of failure in the phantom/clinical image test along with the scores of the subsection, according to MFS, were analyzed. Results: In this study, there were 78 low MFS MRI out of the 279 (28%) MRI. According to MFS, the rate of failure in high contrast spatial resolution of the phantom test was not different. The rate of failure and mean scores in the low contrast object detectability of the phantom test and the mean scores of the brain clinical image test were significantly different according to MFS. Conclusion: The low MFS MRI is constantly being spread due to used equipment in medical facilities. Quality control of low MFS MRI can be important because less than 1 T MRI received significantly lower scores in both phantom and brain clinical image tests. 목적: 자기공명영상장치(MRI)의 분포를 자장세기별로 조사하고, 자장세기별로 품질관리 검사에서 판정의 실태와 팬텀 및 임상영상검사의 개별항목 평가점수에 어떤 상관관계가 있는지 분석하였다. 대상과 방법: 2009년에 한국의료영상품질관리원(이하 영품원)에 정밀검사가 의뢰된 MRI 장비 279대를 대상으로 하였다. 영품원의 자료에서 자장세기별, 의료기관종별, 생산연도, 신품 여부에 따른 국내 MRI 장비의 설치현황을 조사하였다. MRI 자장세기별로 팬텀/임상검사의 부적합 현황과 MRI 팬텀영상검사와 임상영상검사의 항목별 점수를 조사하여 자장세기와의 관계를 분석하였다. 결과: 1 tesla (이하 T) 미만의 저자장 MRI 장비는 78대였다. 공간 분해능의 부적합 빈도는 자장세기에 따라 영향을 받지 않았다. T1 및 T2 강조영상의 대조도 분해능에서 0.3 T 이하의 MRI 장비 49대 중 36(T1) 및 42(T2)대, 1 T 미만의 장비 29대 중 7(T1) 및 18(T2)대가 부적합 판정을 받았고, 1 T 이상 장비는 0(T1) 및 4(T2)대가 부적합 판정을 받아서 통계적으로 유의한 차이를 보였다. 자장세기별로 1 T 미만의 장비와 1 T 이상의 장비는 대조도 분해능의 평균값과 영상정보항목 및 영상대조도 항목점수의 평균값에서 통계적으로 유의한 차이를 보였다. 결론: 저자장 MRI 장비의 사용 빈도가 여전히 높았다. 품질관리 영상검사의 개별항목 평가점수가 1 T 미만의 저자장 장비에서 낮으므로 저자장 장비의 품질관리가 매우 중요하다.

MRI 작동시 발생하는 소음의 특성 및 영향 평가

장희라(Hee-La Jang),송현옥(Hyun-Og Song),김재수(Jae-Soo Kim) 한국생활환경학회 2018 한국생활환경학회지 Vol.25 No.2

Magnetic resonance imaging (MRI) in modern medical science is a method of imaging by putting a person into a device generating a magnetic field to generate high frequency and analyze the signals generated from inside the body. However, MRI causes serious noises while coils move within the device to generate a strong magnetic field. These noises can give serious physical and psychological distress to patients. For this reason, various data are needed to reduce the noises generated from MRI operation; however, South Korea has had almost no relevant research. From this perspective, this study selected four MRI devices with different degrees of a magnetic field, measured noises for each source of MRI operation, and analyzed the waveform, the sound pressure level based on frequency, and the weighted sound level or dB(A). On the basis of these data, MRI operation noises were evaluated with dB(A) and NR to determine how much they affected patients. The MRI operation noises could be divided into four waveforms and most of them were extremely high in the medium-to-high frequency bands, with the exception of the WN noises. When the MRI operation noises were evaluated with dB(A), the NR curve, and PSIL, 0.3T of the magnetic field led to 57.1-64 dB(A), NR 53-62, and 1.98-3.96 m for medium sound, and 4.26-8.31 m for loud sound, with no significant effect on patients. In contrast, 1-3T of the magnetic field led to 74.4-90.9 dB(A) and NR 72-89 for Noise T1, 85.9- 91.7 dB(A) and NR 83-90 for Noise T2, 90.5-28.1 dB(A) and NR 87-98 for Noise D, 79.4-89.8 dB(A) and NR 77- 89 for Noise G, 0.06-0.65 m for medium sound, and 0.12-1.29 m for loud sound in terms of PSIL. Because of patients’ exposure to very serious noises, it is urgent to take measurements then. In particular, 1-3T of the magnetic field, which can affect patients, led to 100-1,000 Hz of grading frequency for the NR curve; therefore, it is essential to lower the noise level of this band with the objective of reducing damages from the exposure to serious noises during an MRI scan.

Analysis of Health Insurance Standards and Utilization of MRI in Korea: Based on Health Insurance Claim Data

Young-Kwon Cho 한국방사선학회 2018 한국방사선학회 논문지 Vol.12 No.7

본 연구는 MRI 건강보험 급여기준 적용 연혁과 건강보험 청구 자료를 바탕으로 MRI 진료 현황(검사 수, 진료금액)을 분석하여 추후 MRI 급여기준 확대 시 참고할 수 있는 기초자료를 제공하기 위해 시행되었다. MRI 검사가 급여로 적용되기 시작한 것은 2005년으로 초기에는 일부 질환에 대해서만 적응증이 제한되었으나, 2010년, 2013년, 2016년, 2018년 급여 대상이 확대되었으며, 보건복지부는 2021년에는 모든 MRI 검사에 대해 건강보험을 적용키로 하였다. 2010년부터 2017년까지 MRI 검사수와 진료금액 변화는 검사수는 2010년 대비 2017년도에 86.7% 증가하였고, 진료금액은 53.5% 증가하였다. 일반적 특성에 따른 MRI 진료 현황은 여성이 남성보다 검사수가 많았고, 연령별로는 70-79세 연령대가 검사수가 가장 많았다. 진료 형태는 외래 검사가 입원검사 보다 많았으며, 의료기관 형태에 따라서는 상급종합병원의 검사수가 가장 많았다. 검사 부위별로는 뇌 MRI 검사수가 가장 높은 비율을 차지하였다. 2013년 12월 심장질환과 크론병에 급여 확대에 따른 진료 현황 변화를 분석한 결과 심장 MRI와 복부 MRI 검사수가 2013년 대비 2014년에 증가 하였다. 하지만 전체 대비 검사수가 차지하는 비율이 낮고 질병명과 연계하지 못한 제한점으로 전체 MRI 검사수 증가에 영향을 주었다고 보기는 어려울 것이다. 우리나라는 건강보험 보장성 강화를 위하여 MRI 급여기준을 지속적으로 확대하고 있다. 건강보험 지속 가능성과 정책 효과 평가를 위해 추후 지속적인 모니터링이 필요할 것이다. This study analyzed the current status of MRI (frequency, amount of treatment) based on the history of application of the MRI health insurance benefit standard and health insurance claim data. MRI examinations began as a health insurance benefit in 2005. In 2005, the indications were restricted for some diseases, but coverage for benefits in 2010, 2013, 2016, and 2018 was expanded. In 2021, the Ministry of Health and Welfare decided to apply health insurance for all MRI examinations. From 2010 to 2017, the number of MRI examinations increased by 86.7% in 2017 compared to 2010, and the amount of treatment increased by 53.5%. According to general characteristics, the number of MRI examinations was higher in women than in men. By age, the number of examinations was the highest among ages 70-79. Outpatient examinations were more frequent than inpatient examinations, and the number of examinations in the tertiary hospitals was the highest among the types of hospitals. The number of brain MRI examinations was the highest in each exam site. In December 2013, the standard of MRI was expanded for heart disease and Crohn's disease, the number of cardiac MRI and abdominal MRI examinations increased in 2014 compared to 2013. However, the number of examinations is small and not associate with the disease, it would be difficult to say that it affected the increase in the total number of MRI examinations. To assess health insurance sustainability and policy effectiveness, monitoring will be necessary.

MRI실의 음향성능 개선 및 방음보호구 착용을 통한 MRI 소음 저감대책

장희라 ( Hee-la Jang ),김재수 ( Jae-soo Kim ) 한국환경기술학회 2018 한국환경기술학회지 Vol.19 No.3

현대 의학에 쓰이는 MRI(Magnetic Resonance Imaging)는 자기장을 발생시켜 각 조직에서 나오는 신호의 차이를 측정하여 영상화 하는 기술로서 최근 그 정확성과 방사선에 노출되지 않아 인체에 무해하다는 장점으로 인해 많이 사용되어지는 검사방법이다. 그러나 이러한 MRI는 강한 자기장을 발생시키기 위해 코일이 움직이는 과정에서 매우 심각한 소음이 발생하게 되며, 이러한 소음으로 인해 검사를 받는 환자들에게 물리적·심리적 고통을 주고 있다. 따라서 MRI 작동소음 저감을 위한 다양한 연구들이 필요하나 국내의 경우 아직까지 이에 대한 연구와 자료들이 매우 부족한 상황이다. 이러한 관점에서 본 연구에서는 MRI작동소음 저감을 위해 MRI실 내부의 흡음요소를 증가시키는 방법과 방음보호구를 착용하는 방법에 따른 소음저감효과를 분석하였다. 연구결과 자기장의 세기 0.3T는 내부 흡음력 증가나 방음보호구 착용 중 한 가지 방법만으로도 60dB(A)이하로 낮아져 별다른 문제가 없었다. 그러나 자기장의 세기가 1∼3T인 경우에는 대부분 60dB(A) 이상으로 나타나 환자들에게 많은 영향을 주기 때문에 적절한 대책이 필요할 것으로 판단된다. 따라서 2가지 방법을 모두 사용하면 자기장의 세기가 3T인 D Source를 제외하고는 38.4∼58.4dB(A)로 나타나 환자에게 영향을 주지 않는 정도로 소음레벨이 낮아졌다. 뿐만 아니라 3T의 D Source의 경우도 64.1∼67.1dB(A)로 나타나 폭로시간이 길지 않을 경우 환자들에게 큰 영향을 미치지는 않을 것으로 판단된다. 따라서 MRI실 내부의 흡음력을 증가시키고 방음보호구를 착용할 경우 MRI진료를 받는 환자들에게 안정적인 진료 환경을 제공할 수 있을 것으로 판단된다. 이러한 소음저감 대책방안은 향후 MRI 작동소음의 저감대책을 수립하는데 유용한 자료로 활용될 수 있을 것으로 사료된다. MRI in modern medical science is a technique of imaging by generating a magnetic field to measure and image variation in signals from each tissue and has recently been applied frequently both because of its accuracy and because it does no harm to the human body without radiation exposure. However, MRI causes serious noises while coils move to generate a strong magnetic field and the noises are giving serious physical and psychological distress to the patients. For this reason, various studies are needed to reduce the noises generated from MRI operation; however, South Korea has had very few relevant studies or data. From this perspective, this study analyzed the effectiveness of the methods of increasing the absorption elements within MRI rooms and wearing hearing protection device in reducing noises generated from MRI operation. As a result of the study, the magnetic field strength of 0.3T was lowered to ≤60dB(A) only by increasing absorbing power within MRI rooms or wearing hearing protection device. However, good measures should be taken for 1-3T of a magnetic field ≥60dB(A), which can significantly affect patients. Applying both methods lowered the noise level so that it had no effect on patients with 38.4-58.4dB(A), with the exception of D Source with 3T for intensity of a magnetic field. Moreover, D Source with 64.1-67.1dB(A) for 3T is expected to have no significant effect on patients if exposure time is not long. It is expected, therefore, that the efforts to increase absorbing power within MRI rooms and wear hearing protection device will provide a stable examination environment to patients getting an MRI scan. This plan for reducing noises is expected to be useful in developing a measure against noises generated from MRI operation.

MRI 보험급여 적용이 진료이용량에 미치는 영향: 한 종합병원의 청구자료를 중심으로

김선희 ( Seon Hee Kim ),김춘배 ( Chun Bae Kim ),조경희 ( Kyung Hee Cho ),강임옥 ( Im Ok Kang ) 한국보건행정학회 2008 보건행정학회지 Vol.18 No.2

As medical insurance had been implemented for Magnetic Resonance Imaging (MRI) from January 1,2005, this study investigated whether there had been any change in the amount of the medical care utilization of patients who undertook MRI before and after the insurance coverage, and was to examine factors affecting the amount of medical care utilization of MRI. Data were collected from patients who undertook MRI before and after the insurance coverage for a year at a general hospital in Kyeonggi-do. Χ2 and t-test were used for the analysis of their general characteristics, the number of MRI, and its medical costs before and after the insurance coverage, and hierarchical multiple regression analysis for the factors affecting the amount of the medical care utilization of MRI. The results of this study were as follows. First, the number of MRI after the insurance coverage was significantly decreased. Second, there was no significant difference in the total medical costs of MRI after the insurance coverage, but a significant difference was found in patient`s share of medical costs. Third, six variables were found to be affecting the amount of the medical care utilization of MRI, and the variables showed to lead the number of MRI decrease after the insurance coverage. These six factors explained 21.4% of the total number of MRI. As MRI had been covered by insurance, the use of MRI a nd patient`s share of the costs were deceased, but the total medical costs were not affected. Reasons for that could be found in that MRI insurance, different from the case of CT insurance coverage, was allowed not to cover some items and the kinds of diseases subjected to the insurance coverage were extremely limited, lowering insurance prescription rate. In addition to that, the average medical cost of MRI was not changed after the insurance coverage. Therefore, as future measures for the MRI insurance coverage, it should be considered to allow insurance coverage to no coverage items and to expand the scope of benefit coverage, or to lower patient`s share of the costs. Furthermore, researches should be done to explore how recipients will act and how suppliers will react if the coverage is expanded, including expanding the scope of coverage and reducing patient`s share of the costs, as well as to conduct research on its economic analysis according to case mix.

한국의 MRI 건강보험 급여기준 및 진료이용에 관한 연구

조영권 ( Young-kwon Cho ) 한국방사선학회 2018 한국방사선학회 논문지 Vol.12 No.7

본 연구는 MRI 건강보험 급여기준 적용 연혁과 건강보험 청구 자료를 바탕으로 MRI 진료 현황(검사 수, 진료금액)을 분석하여 추후 MRI 급여기준 확대 시 참고할 수 있는 기초자료를 제공하기 위해 시행되었다. MRI 검사가 급여로 적용되기 시작한 것은 2005년으로 초기에는 일부 질환에 대해서만 적응증이 제한되었으나, 2010년, 2013년, 2016년, 2018년 급여 대상이 확대되었으며, 보건복지부는 2021년에는 모든 MRI 검사에 대해 건강보험을 적용키로 하였다. 2010년부터 2017년까지 MRI 검사수와 진료금액 변화는 검사수는 2010년 대비 2017년도에 86.7% 증가하였고, 진료금액은 53.5% 증가하였다. 일반적 특성에 따른 MRI 진료 현황은 여성이 남성보다 검사수가 많았고, 연령별로는 70-79세 연령대가 검사수가 가장 많았다. 진료 형태는 외래 검사가 입원검사 보다 많았으며, 의료기관 형태에 따라서는 상급종합병원의 검사수가 가장 많았다. 검사 부위별로는 뇌 MRI 검사수가 가장 높은 비율을 차지하였다. 2013년 12월 심장질환과 크론병에 급여 확대에 따른 진료 현황 변화를 분석한 결과 심장 MRI와 복부 MRI 검사수가 2013년 대비 2014년에 증가 하였다. 하지만 전체 대비 검사수가 차지하는 비율이 낮고 질병명과 연계하지 못한 제한점으로 전체 MRI 검사수 증가에 영향을 주었다고 보기는 어려울 것이다. 우리나라는 건강보험 보장성 강화를 위하여 MRI 급여기준을 지속적으로 확대하고 있다. 건강보험 지속 가능성과 정책 효과 평가를 위해 추후 지속적인 모니터링이 필요할 것이다. This study analyzed the current status of MRI (frequency, amount of treatment) based on the history of application of the MRI health insurance benefit standard and health insurance claim data. MRI examinations began as a health insurance benefit in 2005. In 2005, the indications were restricted for some diseases, but coverage for benefits in 2010, 2013, 2016, and 2018 was expanded. In 2021, the Ministry of Health and Welfare decided to apply health insurance for all MRI examinations. From 2010 to 2017, the number of MRI examinations increased by 86.7% in 2017 compared to 2010, and the amount of treatment increased by 53.5%. According to general characteristics, the number of MRI examinations was higher in women than in men. By age, the number of examinations was the highest among ages 70-79. Outpatient examinations were more frequent than inpatient examinations, and the number of examinations in the tertiary hospitals was the highest among the types of hospitals. The number of brain MRI examinations was the highest in each exam site. In December 2013, the standard of MRI was expanded for heart disease and Crohn's disease, the number of cardiac MRI and abdominal MRI examinations increased in 2014 compared to 2013. However, the number of examinations is small and not associate with the disease, it would be difficult to say that it affected the increase in the total number of MRI examinations. To assess health insurance sustainability and policy effectiveness, monitoring will be necessary.

MRI 영상의 PSNR 평가

강광수 ( Kwangsoo Kang ),이준행 ( Junhaeng Lee ) 한국방사선학회 2009 한국방사선학회 논문지 Vol.3 No.4

MRI System은 각종 여러 가지 Parameter들로 구성되어 있다. 그중 MRI 영상의 화질을 빼놓고 MRI를 논한다는 것은 어려운 일이다. 각종 Parameter들이 개발되고 발전되어오면서 MRI영상에서도 예전 System에서 보여지는 영상과는 비교할 수 없을 정도의 고화질을 출력하고 있다. 그리고 방사선 영상 System이 고식적인 Film방식에서 digital방식으로 전환되어가고 있고 그에 따른 병원의 모든 시스템이 전산화가 되어가고 있다. 방사선 영상의 관리에 있어서 저장 이라는 부분이 아주 중요한 몱을 차지하고 있다. 그 방대한 자료를 Server에 저장하는 방법으로는 압축을 이용 하여 저장하는 방법을 사용하게 된다. 이 때 발생한 문제점은 원본 영상에 비해 압축시 영상의 화질 저하가 발생한다는 것이다. 의료 영상에서는 조그마한 화질저하도 오진의 우려가 있으므로 각별히 주의해야할 사항이다. 본 논문에서는 병원에서 진료중인 영상을 대상으로 각각의 파일 변환과 원본과의 비교, 원본 영상과 진료에 사용되어지는 모니터에서의 MRI 영상의 화질을 PSNR을 이용한 평가와 영상 평가방법에 의한 평가를 하였다. 실험결과 원본과 각종 영상 압축방법을 이용하여 압축한 영상을 비교 분석 하였는데 화질저하가 거의 나타나지 않았다. 하지만 원본영상을 display하는 모니터의 화질 에서 상당한 문제점이 드러났다. 판독용 모니터 와 의료용 모니터에서는 손색없는 고해상도의 영상을 출력해 냈는가 반면 일반 CRT, LCD 모니터에서는 각종 노이즈 , 영상왜곡등 많은 문제점들이 나타났다 The Magnetic Resonance Imaging (MRI) systems consist of various parameters. Among them, the image quality can be arguably the most important part of the systems. As the other components in MRI systems have been developed and evolved, the MRI image quality has been advanced remarkably. And, the radiation imaging system is being converted from the Film to the digital method, which drives the computerization of many hospitals The management of the tremendous radiation images becomes more critical. The data compression is used to store such large data in a network server. When the image files are compressed, the image quality degrades comparing to its original images. Even slight quality degradation of a medical image could cause an erroneous diagnosis, so the images must be handled carefully. This thesis studied the image assessment methods of comparing the quality of the compressed image to its original, and the quality of the original and the displayed images of the MRI systems via PSNR with actual medical images used in hospitals. As a result, no noticeable quality degradation was found comparing the compressed images with various digital compression methods and the original images. However, it was a different story comparing the original images and the displayed images on MRI monitors. Some noise or image distortion was visible using any regular CRT or LCD monitors were used while the special monitors designed for the MRI imaging and medical images displayed high definition images.

자기공명영상진단장치의 이용실태에 관한 조사연구

안상경,경광현,박기정,한상용,용군호,최종학 국립보건연구원 1992 국립보건원보 Vol.29 No.2

리플릿 교육 후 MRI 환자의 이해도 및 만족도 비교분석

박창희,한상현 한국방사선학회 2022 한국방사선학회 논문지 Vol.16 No.2

Recently, the penetration rate of Magnetic Resonance Imaging (MRI) is higher than the average among OECD member countries, and the number of MRI scans is increasing. However, MRI scans take longer than other medical devices, and patient movement must be minimized. Therefore, patient discomfort always follows. When the examination is performed in the discomfort of the patient, it is difficult to perform an accurate examination, and it is difficult to obtain an image of diagnostic value. So, in the past, the patient was asked to read the written guide for the risk and cooperation of MRI, but it was composed of technical terms and difficult-to-understand sentences, so it was difficult to understand. The purpose of this study is to supplement these problems and increase the understanding of MRI scans to help acquire images of diagnostic value. In addition, it is intended to evaluate the excellence of leaflet education by evaluating the understanding and satisfaction of patients. As shown in the results of this study, understanding and satisfaction scores were higher after education than before leaflet education, and it was found that there was a difference in understanding according to academic background. However, there was no difference in the number of MRI scans. That is, there was no difference in the number of inspections due to leaflet education. In the future, leaflet education will be widely used for MRI examination, and it is necessary to study the qualitative evaluation of images after leaflet education in the future. 최근 OECD 가입국 중에 MRI 보급률이 평균보다 높게 보급되고 있고, MRI 검사의 횟수도 증가하고 있다. MRI 검사는 다른 의료장비에 비해 검사시간이 길며, 환자의 움직임이 최소화되어야 한다. 그러므로 환자의 불편이 항상 뒤따른다. 이러한 불편한 환경에서 검사 시 정확한 검사가 어려우며 진단적 가치의 영상획득에는 어려움이 따른다. 기존 MRI 검사 시 MRI의 위험성과 협조를 구하기 위해 글로 되어있는 안내문을 제공 하였으나, 전문용어와 이해하기 어려운 문장들로 구성이 되어있어 이해도가 낮아졌다. 본 연구는 이러한 문제점을 보완하고 MRI 검사의 이해도를 높여 진단적 가치가 있는 영상획득에 도움이 되고자 하였다. 그리고 환자의 이해도와 만족도를 평가하여 리플릿 교육의 우수성을 평가하고자 한다. 본 연구의 결과에서 나타났듯이 리플릿 교육 전보다 교육 후의 이해도와 만족도의 점수는 각각 4.44±0.55 점, 4.85±0.37 점으로 높았으며, 학력에 따라 이해도의 차이는 유의함을 알 수 있었다. 그러나 MRI 검사 횟수는 차이가 없었다. 향후 MRI 검사에서 다양하고 이해하기 쉬운 리플릿 교육이 널리 보급되어 환자의 적극적인 검사 협조로 보다 질 좋은 영상을 획득할 수 있기를 기대한다.

Approximate Subject Specific Pseudo MRI from an Available MRI Dataset for MEG Source Imaging

Gohel, Bakul,Lim, Sanghyun,Kim, Min-Young,Kwon, Hyukchan,Kim, Kiwoong Frontiers Media S.A. 2017 Frontiers in neuroinformatics Vol.11 No.-

<P>Computation of headmodel and sourcemodel from the subject's MRI scan is an essential step for source localization of magnetoencephalography (MEG) (or EEG) sensor signals. In the absence of a real MRI scan, pseudo MRI (i.e., associated headmodel and sourcemodel) is often approximated from an available standard MRI template or pool of MRI scans considering the subject's digitized head surface. In the present study, we approximated two types of pseudo MRI (i.e., associated headmodel and sourcemodel) using an available pool of MRI scans with the focus on MEG source imaging. The first was the first rank pseudo MRI; that is, the MRI scan in the dataset having the lowest objective registration error (ORE) after being registered (rigid body transformation with isotropic scaling) to the subject's digitized head surface. The second was the averaged rank pseudo MRI that is generated by averaging of headmodels and sourcemodels from multiple MRI scans respectively, after being registered to the subject's digitized head surface. Subject level analysis showed that the mean upper bound of source location error for the approximated sourcemodel in reference to the real one was 10 ± 3 mm for the averaged rank pseudo MRI, which was significantly lower than the first rank pseudo MRI approach. Functional group source response in the brain to visual stimulation in the form of event-related power (ERP) at the time latency of peak amplitude showed noticeably identical source distribution for first rank pseudo MRI, averaged rank pseudo MRI, and real MRI. The source localization error for functional peak response was significantly lower for averaged rank pseudo MRI compared to first rank pseudo MRI. We conclude that it is feasible to use approximated pseudo MRI, particularly the averaged rank pseudo MRI, as a substitute for real MRI without losing the generality of the functional group source response.</P>