• Korean Management Science Review
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• v.21 no.2
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• pp.93-109
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• 2004

The imports of used medical equipment such as CT. MRI have been rapidly increased every year. How to manage those medical equipment has been one of critical issues in the government sector. In this study, we demonstrate how benefit/cost analysis using the Analytic Hierarchy Process (AHP) can be applied to the comparison of used CT/MRI and new CT/MRI. The final results show that the new CT/MRI is more attractive than the used CT/MRI.

• Progress in Medical Physics
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• v.31 no.3
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• pp.35-53
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• 2020

The authors congratulate the cerebrations for the 30 years of the Korean Society of Medical Physics (http://www.ksmp.or.kr/). The paper is published to recognize the anniversary. Geon-Ho Jahng invited Professor Z. H. Cho to join to submit this manuscript because he has been one of the leaders in the field of magnetic resonance imaging (MRI) during the last 40 years. In this review, we describe the development and clinical histories of MRI internationally and domestically. We also discuss diffusion and perfusion MRI, molecular imaging using MRI and MR spectroscopy (MRS), and the hybrid systems, such as positron emission tomography-MRI (PET-MRI), MR-guided focused ultrasound surgery (MRgFUS), and MRI-guided linear accelerators (MRI-LINACs). In each part, we discuss the historical evolution of the developments, technical developments, and clinical applications.

• Korean Journal of Radiology
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• v.22 no.1
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• pp.9-22
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• 2021

Diffusion-weighted (DW) magnetic resonance imaging (MRI) is a rapid, unenhanced imaging technique that measures the motion of water molecules within tissues and provides information regarding the cell density and tissue microstructure. DW MRI has demonstrated the potential to improve the specificity of breast MRI, facilitate the evaluation of tumor response to neoadjuvant chemotherapy and can be employed in unenhanced MRI screening. However, standardization of the acquisition and interpretation of DW MRI is challenging. Recently, the European Society of Breast Radiology issued a consensus statement, which described the acquisition parameters and interpretation of DW MRI. The current article describes the basic principles, standardized acquisition protocols and interpretation guidelines, and the clinical applications of DW MRI in breast imaging.

• Health Policy and Management
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• v.8 no.1
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• pp.155-182
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• 1998

There exists a remarkable differences in use of MRI scanning among income classes. The poor can hardly utilize it. This is because, among high cost technnologies, MRI is the only equipment not covered under health insurance benefits in Korea. This study was designed 1) to reveal the status of nation-wide MRI installation, customary charges and per unit annual scanning performance, and 2) to analyse factors influencing the above variables. The data for this study came from "MRI Prevalence Survey" conducted by the National Federation of Medcial Insurance(NFMI) in 1997, and were analyzed through SAS packages for T-test, analysis of variance and stepwise multiple regression. Data were collected from 188 hospitals equipped with MRI scanners. Major findings are summarized as follows : The number of MRI scanners has increased from 69 in 994 to 158 in 1996(2.3 times) while per unit annual scanning performance has risen by 11.2% from 2,173 cases in 1994 to 2,417 cases in 1996. Such a rapid increase was made possible mainly due to the inclusion of CT scanning under the health insurance benefit package. The customary charges for MRI scanning with or without contrast media, on average, amounted to 484,000 Won and 402,000 Won, respectively, with the percentile increase of 17.8% and 8.1% each during the same time. Korea ranks the third worldwidely in terms of number of MRI installations, 4.8 scanners per one million persons, only next to Japan and United States. Geographical variation of MRI, however, was rather high, 7.91 unit, in Cheju area compared to 1.82 in Kyongnam area. Variations of customary charges of MRI scanning can be explained as much as by 44.8% by both the total amount of claims to NFMI and geographical variable. The charges were more likely to be higher in metropolitan areas like Seoul and in hospitals with a bigger amount of claims. While those of per unit annual scanning performance can be explained as much as by 30.7% by both MRI installation cost and level of MRI-installed organizations. Per capital scannig performance was higher in tertiary hospitals and hospitals equipped with more expensive scanners than hospitals with less expensive scanners. Two measures are called for the remedying the existing excessive abundance in MRI units in korea : One is to set a ceiling of MRI units in an area like a province or a metropolitan district. The other is to establish a committee on introduction of high cost technologies for reviewing its effective use.ctive use.

• The Journal of the Korean bone and joint tumor society
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• v.20 no.2
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• pp.60-65
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• 2014

Purpose: To diagnose soft tissue tumor, such as lipoma and Schwannoma, magnetic resonance imaging (MRI) is sufficient in most cases. However, various characteristics are found in MRI images of Schwannoma, thus other type of tumors are often misdiagnosed as Schwannoma with MRI images. In this study, we evaluate the diagnostic value of specific MRI findings of Schwannoma. Materials and Methods: From January 2002 to May 2013, 104 patients who are suspected as Schwannoma rith MRI images are included in data, and the final diagnosis is confirmed with biopsy. Patients are divided into group 1 and group 2 who are confirmed as Schwannoma and other disease with biopsy, respectively. Results: 92 patients were diagnosed as Schwannoma (group 1) and 12 patients were diagnosed as other disease (group 2). We investigate the diagnostic value of specific MRI findings of Schwannoma. 41 patients of group 1 (45%) and 0 patients of group 2 (0%) showed target sign, 47 patients of group 1 (51%) and 2 patients of group 2 (17%) showed fascicular sign, 44 patients of group 1 (48%) and 5 patients of group 2 (42%) showed fat split sign, 28 patients of group 1 (30%) and 1 patients of group 2(9%) showed nerve entering and exiting sign, and 8 patients of group 1 (9%) and 6 patients of group 2 (50%) showed none of four specific findings on their MRI images. 52 patients of group 1 (57%) and 5 patients of group 2 (42%) have tumors on the pathway of nerve. Target sign could be considered as the best diagnostic value of the sign we investigate (p<0.05). Conclusion: Although specific MRI findings have powerful diagnostic value, patients are often misdiagnosed as Schwannoma with MRI findings. Therefore, if patients who are suspected as Schwannoma based on MRI findings have no target sign on their MRI images, we should consider the possibility of other disease.

• Journal of Radiation Protection and Research
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• v.31 no.2
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• pp.91-96
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• 2006

The effects of Magnetic resonance imaging (MRI) on mouse embryos at the early stage of organogenesis were investigated. Pregnant ICR mice were exposed on day 8 of gestation to MRI at 0.5 T for 0.5 hour to 3 hours. The mortality rates of embryos or fetuses, the incidence of external malformations, fetal body weight and sex ratio were observed at day 18 of gestation. A significant increase in embryonic mortality was observed after exposure to either 0.5 T MRI for 0.5 hour or 2 hours. However, the exposure to MRI for 1 hour or 3 hours did not induce any significant increase in embryonic mortality when compared with control. External malformations such as exencephaly, cleft palate and anomalies of tail were observed in all experimental groups exposed to each MRI. A statistically significant increase of external malformations was observed in all groups treated with 0.5 T MRI for 0.5 hour and 3 hours. The incidence of external malformations in the mice group exposed to 0.5 T MRI for 0.5-hour was found to be higher than those of mice group exposed to 0.5 T MRI for 2 hours. The effects of MRI on the external malformations might not to be dose-dependent. There was no statistically significant difference in fetal body weight and sex ratio among each MRI exposure groups.

• Investigative Magnetic Resonance Imaging
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• v.24 no.3
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• pp.154-161
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• 2020

Purpose: A CT angiography spot sign (CTA-spot) is a significant predictor of the early expansion of an intracerebral hemorrhage (ICH-Ex). Dynamic-susceptibility-contrast magnetic resonance imaging (DSC-MRI) can track the real-time leaking of contrast agents. It may be able to indicate active bleeding, like a CTA-spot. Materials and Methods: From September 2014 to February 2017, we did non-contrast CT, CTA, and DSC-MRI examinations of seven patients with acute ICH. We investigated the time from symptom onset to the first contrast-enhanced imaging. We evaluated the time course of the contrast leak within the ICH at the source image of the DSC-MRI and the volume change of ICH between non-contrast CT and DSC-MRI. We compared the number of slices showing CTA-spots and DSC-MRI leaks. Results: The CTA-spot and DSC-MRI leak-sign were present in four patients, and two patients among those showed ICH-Ex. The time from the symptom onset to CTA or DSC-MRI was shorter for those with a DSC-MRI leak or CTA-spot than for three patients without either (70-130 minutes vs. 135-270 minutes). The leak-sign began earlier, lasted longer, and spread to more slices in the patients with ICH-Ex than in those without ICH-Ex. The number of slices of the DSC-MRI leak and the number of the CTA-spot were well correlated. Conclusion: DSC-MRI can demonstrate the leakage of GBCA within hyperacute ICH, showing the good contrast between hematoma and contrast. The DSC-MRI leakage sign could be related to the hematoma expansion in patients with ICH.

• Korean Journal of Radiology
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• v.20 no.1
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• pp.102-113
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• 2019

Objective: To assess the accuracy and potential bias of computed tomography (CT) ventricular volumetry using semiautomatic three-dimensional (3D) threshold-based segmentation in repaired tetralogy of Fallot, and to compare them to those of two-dimensional (2D) magnetic resonance imaging (MRI). Materials and Methods: This retrospective study evaluated 32 patients with repaired tetralogy of Fallot who had undergone both cardiac CT and MRI within 3 years. For ventricular volumetry, semiautomatic 3D threshold-based segmentation was used in CT, while a manual simplified contouring 2D method was used in MRI. The indexed ventricular volumes were compared between CT and MRI. The indexed ventricular stroke volumes were compared with the indexed arterial stroke volumes measured using phase-contrast MRI. The mean differences and degrees of agreement in the indexed ventricular and stroke volumes were evaluated using Bland-Altman analysis. Results: The indexed end-systolic (ES) volumes showed no significant difference between CT and MRI (p > 0.05), while the indexed end-diastolic (ED) volumes were significantly larger on CT than on MRI (93.6 ± 17.5 mL/m² vs. 87.3 ± 15.5 mL/m² for the left ventricle [p < 0.001] and 177.2 ± 39.5 mL/m² vs. 161.7 ± 33.1 mL/m² for the right ventricle [p < 0.001], respectively). The mean differences between CT and MRI were smaller for the indexed ES volumes (2.0-2.5 mL/m²) than for the indexed ED volumes (6.3-15.5 mL/m²). CT overestimated the stroke volumes by 14-16%. With phase-contrast MRI as a reference, CT (7.2-14.3 mL/m²) showed greater mean differences in the indexed stroke volumes than did MRI (0.8-3.3 mL/m²; p < 0.005). Conclusion: Compared to 2D MRI, CT ventricular volumetry using semiautomatic 3D threshold-based segmentation provides comparable ES volumes, but overestimates the ED and stroke volumes in patients with repaired tetralogy of Fallot.

• The Journal of the Korean bone and joint tumor society
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• v.11 no.1
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• pp.25-31
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• 2005

Purpose: This study was designed to know the usefulness of the MRI to distinguish lipoma and well differentiated liposarcoma (WDL). Materials and methods: 47 lipomatous tumors with MRI were reviewed among the 107 lipomatous tumors operated in our department. MRI examinations and their corresponding pathology reports were compared to determine sensitivity, specificity, diagnostic ability, positive predictable value and negative predictable value. Statistical analysis was performed to know the relationship between malignancy of the tumor (WDL) with the age and gender of the patients, and location, depth, size and the enhancement of tumors in MRI. Results: Among 28 lipoma in MRI examinations, 26 were proved as lipoma in pathology, and only 6 were WDL from 19 suspicious lesions in MRI, and others were proved as lipoma variants mostly. The varieties of lipoma variants were fibrolipoma, angiolipoma, spindle cell lipoma, lipoblastoma and angiomyolipoma. The sensitivity, specificity, diagnostic ability, positive predictable value and negative predictable value of MRI were 100%, 68 %, 72%, 31% and 100% in WDL, and 90%, 89%, 89%, 93% and 84% in lipoma. Among the variants to distinguish WDL and lipoma, the size of tumor and enhancement in MRI were significant statistically (p<0.05). Conclusion: MRI was highly sensitive in detection of WDL and highly specific in detection of simple lipoma. The size of tumor and enhancement in MRI were significant variants to distinguish WDL and lipoma. When MRI finding is non-specific, it is more likely to represent one of lipoma variants.

• Journal of the Korean Society of Radiology
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• v.3 no.4
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• pp.13-21
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• 2009

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.