• Title, Summary, Keyword: MRI

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Value of Repeat Brain MRI in Children with Focal Epilepsy and Negative Findings on Initial MRI

  • Jeon, Tae Yeon;Kim, Ji Hye;Lee, Jeehun;Yoo, So-Young;Hwang, Sook Min;Lee, Munhyang
    • Korean Journal of Radiology
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    • v.18 no.4
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    • pp.729-738
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    • 2017
  • Objective: To evaluate the value of repeat brain magnetic resonance imaging (MRI) in identifying potential epileptogenic lesions in children with initial MRI-negative focal epilepsy. Materials and Methods: Our Institutional Review Board approved this retrospective study and waived the requirement for informed consent. During a 15-year period, 257 children (148 boys and 109 girls) with initial MRI-negative focal epilepsy were included. After re-evaluating both initial and repeat MRIs, positive results at repeat MRI were classified into potential epileptogenic lesions (malformation of cortical development and hippocampal sclerosis) and other abnormalities. Contributing factors for improved lesion conspicuity of the initially overlooked potential epileptogenic lesions were analyzed and classified into lesion factors and imaging factors. Results: Repeat MRI was positive in 21% (55/257) and negative in 79% cases (202/257). Of the positive results, potential epileptogenic lesions comprised 49% (27/55) and other abnormalities comprised 11% of the cases (28/257). Potential epileptogenic lesions included focal cortical dysplasia (n = 11), hippocampal sclerosis (n = 10), polymicrogyria (n = 2), heterotopic gray matter (n = 2), microlissencephaly (n = 1), and cortical tumor (n = 1). Of these, seven patients underwent surgical resection. Contributing factors for new diagnoses were classified as imaging factors alone (n = 6), lesion factors alone (n = 2), both (n = 18), and neither (n = 1). Conclusion: Repeat MRI revealed positive results in 21% of the children with initial MRI-negative focal epilepsy, with 50% of the positive results considered as potential epileptogenic lesions. Enhanced MRI techniques or considering the chronological changes of lesions on MRI may improve the diagnostic yield for identification of potential epileptogenic lesions on repeat MRI.

Retrospective Review of Magnetic Resonance Imaging of the Lumbosacral Spine: Are We Overinvestigating?

  • Khanduja, Suchit;Loomba, Vivek;Salama-Hannah, Joseph;Upadhyay, Aman;Khanduja, Neha;Chauhan, Gaurav
    • Neurospine
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    • v.15 no.4
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    • pp.383-387
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    • 2018
  • Objective: Lower back pain (LBP) is a worldwide health problem, and magnetic resonance imaging (MRI) is a common modality used to aid in its diagnosis. Although specific guidelines for assessing the necessity of MRI usage exist, the use of MRI as the initial imaging method for LBP seems to be more common than necessary in general practice. Methods: We conducted a retrospective chart review of 313 patients who had undergone MRI of the lumbosacral spine during 2014-2015. We recorded and compared various factors, including age, sex, body mass index, current smoking status, race, symptoms, MRI findings, and progression to surgery within the next year. All rates were compared according to whether the MRI results showed radiographically significant findings (MRI-positive) or not (MRI-negative) using the chi-square or Fisher exact tests (if the expected cell count was <5). All analyses were performed using SAS version 9.4. Results: There were no statistically significant differences in the rates of each symptom between the MRI-positive and MRI-negative groups, which accounted for 58.5% (183 of 313) and 41.5% (130 of 313) of the MRIs, respectively. The difference in the rate of surgery in the next year (18% among MRI-positive patients and 8.5% among MRI-negative patients) was found to be statistically significant (p<0.05). Conclusion: Based on our findings, 41.5% of patients underwent lumbar MRI unnecessarily and 81% of patients with positive MRIs did not have surgery within the next year. Further physician training is needed to avoid unnecessary investigations and expenditures.

Usefulness Evaluation 'Ankle Stress View Compared with MRI scan' of Subacute Ankle Sprain (아급성기 발목염좌에 대한 Stress View와 MRI검사 대비 유용성 평가)

  • Ahn, Byeoung-Ju
    • Journal of the Korean Society of Radiology
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    • v.5 no.4
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    • pp.201-205
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    • 2011
  • Subacute Ankle Sprain patients, 3 tests have been acknowledge for diagnostic precision and thus most commonly used to test their soft tissues, muscles, and ligaments: ankle stress-valgus test, anterior-draw test, and MRI scan. Although not much different from the rest two in its diagnostic value, MRI costs patients some money and time. Also, we have reached the conclusion through an experiment with a group of patients in a certain hospital that the rest two methods is as efficient and useful as MRI in diagnosing ankle joint patients.

Functional Magnetic Resonance Imaging with Arterial Spin Labeling: Techniques and Potential Clinical and Research Applications

  • Kim, Ju Ho;Choi, Dae Seob;Park, Sung Eun;Choi, Ho Cheol;Kim, Seong Hu
    • Investigative Magnetic Resonance Imaging
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    • v.21 no.2
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    • pp.91-96
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    • 2017
  • Purpose: To describe technical methods for functional magnetic resonance imaging (fMRI) study with arterial spin labeling (ASL) compared to blood oxygenation level-dependent (BOLD) technique and discuss the potential of ASL for research and clinical practice. Materials and Methods: Task-based (n = 1) and resting-state fMRI (rs-fMRI) (n = 20) were performed using ASL and BOLD techniques. Results of both techniques were compared. Results: For task-based fMRI with finger-tapping, the primary motor cortex of the contralateral frontal lobe and the ipsilateral cerebellum were activated by both BOLD and ASL fMRI. For rs-fMRI of sensorimotor network, functional connectivity showed similar results between BOLD and ASL. Conclusion: ASL technique has potential application in clinical and research fields because all brain perfusion imaging, CBF measurement, and rs-fMRI study can be performed in a single acquisition.

Current Status of MRI Distribution, Prevailing Charges and Analysis of Its Performance (MRI 분포와 관행수가 현황 및 촬영실적 분석)

  • 문옥륜;장원기;이상이;김철웅;최경혜
    • 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.

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A New Medical Lead for Various MRI Systems (다양한 MRI 시스템에서 사용가능한 의료용 리드선)

  • Kim, Hongjoon;Yoo, Hyoungsuk
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.3
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    • pp.429-432
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    • 2015
  • Radio Frequency (RF) coils in Magnetic Resonance Imaging (MRI) systems interact with a patient's tissues, resulting in the absorption of RF energy by the tissues. The presence of an electrically conducting medical implant may concentrate the RF energy and causes tissue heating near the implant devices. Here we present a novel design for a medical lead to reduce this undesired heating. Specific Absorption Rate (SAR), an indicator of heating, was calculated. Remcom XFdtd software was used to calculate the peak SAR distribution (1g and 10 g) 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 MRI), 128 MHz (3 T MRI) and 300 MHz (7 T MRI) using a model of an MR birdcage body coil. Our results demonstrate that, our proposed design of adding nails to the medical lead can significantly reduce the SAR for different MRI systems.

Cost Benefit Analysis of CT and MRI Using the AHP (AHP를 이용한 CT 및 MRI의 비용편익분석)

  • Cho Keun-Tae;Kim Sung-Jo;Kim Sung-Min;Kim Yong-U;Kim Sung-Je;Cho Yong-Gon
    • 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.

Magnetic Resonance Imaging in Thorax (흉부의 자기공명영상)

  • Choi, Byoung Wook
    • Tuberculosis and Respiratory Diseases
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    • v.56 no.6
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    • pp.571-584
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    • 2004
  • Magnetic Resonance Imaging (MRI) is one of the most advanced imaging techniques in clinical and research medicine. However, clinical application of MRI to the lung or thorax has been limited due to various drawbacks. Low signal intensity of the lung and cardiac and respiratory movements are the most serious problems with MRI in thorax. Nevertheless, MRI is superior to CT in some selected patients with thoracic diseases. The role of clinical MRI in thoracic disease has been widened with improvement of MR equipments and development of new pulse sequences. Otherwise, functional assessment of lung by MRI has been studied for the last decade. These include perfusion MRI with or without contrast enhancement and ventilation MRI with oxygen-enhancement or hyperpolarized noble gas, $^3He$ and $^{129}Xe$.

Diagnostic Value of MRI in Schwannoma (신경초종 진단에 있어 자기공명영상촬영(MRI)의 진단적 가치)

  • Kim, Jeung Il;Kim, Um Ji;Moon, Tae Yong;Lee, In Sook;Song, You Seon;Choi, Kyung Un
    • 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.

The Effects of MRI on Mouse Embryos During Fetal Stage

  • Nakamura, Takashi;Ryu, Myung-Sun;Sakazaki, Takahiko;Itokawa, Yuka;Maenaka, Toshihiro;Masubuchi, Takashi;Sekimoto, Hiroyuki;Kanehara, Masayuki;Kang, Young-Nam;Gu, Yeun-Hwa
    • 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.