• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4891-4895
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• 2010

RF coil is an important component of the Magnetic Resonance Imaging (MRI) system and the performance of RF coil is one of major factors for high SNR images. Sensitivity and RF field uniformity are parameters for evaluating RF coil performance. Since the B1 field is induced by RF coil, MR signal is strongly affected by RF coil structure and arrangement. In receiving MR signal, the RF coil sensitivity to MR Signal is also determined by the induced B1 field of RF coil. Therefore, the spatial distribution of B1 field must be verified. In this work, we performed computer simulation of the basic RF coil structures using Matlab and verified their sensitivity and uniformity through their B1 field distribution. This work will be useful for the advanced multi-channel RF coil design.

• Proceedings of the Korea Contents Association Conference
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• 2017.05a
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• pp.107-108
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• 2017

3차원 위상대조도 기법의 단점인 긴 검사시간으로 인해 임상적 유용성이 떨어진다. 본 논문은 시간매개변수인 병렬영상기법(Grappa) 변경에 따른 혈류정보의 정량적 평가를 통해 차이점을 알아보고 임상적 활용정도를 평가하였다. 자체 제작한 혈류팬텀을 통해 실험하였으며, Grappa을 5번 변경하여 실험하였다. 연구결과, Grappa를 적용하지 않았을 경우 혈류속도는 평균 9.42로 총 4단계를 적용한 혈류속도 차이율은 각각(1.4, 1.5, 0.4, 1.5%)이었으며 flow와 WSS도 각각(1.4, 1.6, 0.8, 25%), (2.1, 1.4, 1.1, 0.8%)이었다. 통계적으로도 유의하지 않아 Grappa를 적용하지 않은 검사법과 혈류정보가 동일하였다.(P>0.05) 긴 검사 시간으로 인해 임상적 활용이 떨어지는 짧은 검사시간을 요하는 소아환자나 중등도 환자 또는 폐쇄공포증 환자에게 시간을 단축한 3차원 위상대조도 기법을 사용하여 단점을 보완한다면 임상적 활용가치가 높아질 것이라 사료된다.

• Investigative Magnetic Resonance Imaging
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• v.15 no.2
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• pp.102-109
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• 2011

Purpose : To retrospectively evaluate the usefulness of diffusion-weighted images, ADC maps and conventional MR images for determination of brain tumor consistency. Materials and Methods : Twenty-three patients with brain tumor underwent MR examinations with T1, T2 and diffusion-weighted images. Regions of interest (ROIs) were drawn in the tumors, and the measured signal intensities (SI) were normalized with the contralateral side. We evaluated the correlation between SI ratios from various images and tumor consistency assessed at surgery. In three patients with both cystic and solid components, each component was evaluated independently. Qualitatively observed SIs were also correlated with tumor consistency. Results : Statistical analysis revealed significant correlation between tumor consistency and ADC ratio (r = -0.586, p = 0.002), SI ratios on T2-weighted images (r = -0.497, p = 0.010), and observed SIs on T2-weighted images (r = -0.461, p = 0.018). The relative ratio of ADC value correlated with tumor consistency most strongly. Conclusion : The measured ratio of ADC, SI ratio and observed SI grade on T2-weighted images can provide valuable information about the consistency of brain tumor.

• Journal of radiological science and technology
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• v.41 no.3
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• pp.193-199
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• 2018

The purpose of this study was to evaluate the convenience and image quality of patients with acute lumbar pain patients at a general hospital in Daejeon using ancillary devices for postural changes and correction. The results of the study are summarized as follows. First, the Turbo S pin Echo technique(TS E) using ancillary equipment has the highest image evaluation rating with an average score of 4.440, which is highly valuable on a diagnosis. Second, the average score for patient the questionnaire 'When using ancillary equipment, I feel that my body is calibrated to side without bias.' was shown as 4.440, which is very useful for the correction of the patient's body when using ancillary equipment. Finally, Breath Hold technique(BH) is very effective in shortening test time of acute lumbar pain patients, because it can reduce test time 86.4% faster than Turbo Spin Echo technique(TSE). The results of the study showed that the use of ancillary equipment to perform the test through the side lying postures helped to reduce the pain and control the patient's breathing, and the diagnostic value of the image was high.

• Investigative Magnetic Resonance Imaging
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• v.6 no.2
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• pp.120-128
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• 2002

Purpose : To demonstrate that the relaxographic method provides additional information such as the distribution of relaxation times and water content which are poentially applicable to clinical medicine. Materials and Methods : First, the computer simulation was performed with the generated relaxation data to verify the accuracy and reliabilility of the relaxographic method (CONTINI). Secondly, in or der to see how well the CONTIN quantifies and resolves the two different ${T_1}$ environments, we calculated the oil to water peak area ratios and identified peak positions of ${T_1}-distribution$ curve of the phantom solutions, which consist of four centrifugal tubes (10 ml) filled with the compounds of 0, 10, 20, 30% of corn oil and distilled water, using CONTIN. Finally, inversion recovery MR images for a volunteer are acquired for each TI ranged from 40 to 1160 msec with TR/TE=2200/20 msec. From the 3 different ROIs (GM, WM, CSF), CONTIN analysis was performed to obtain the ${T_1}$-distribution curves, which gave peak positions and peak area of each ROI location. Results : The simulation result shows that the errors of peak positions were less in the higher peak (centered ${T_1}=600$ msec) than in the lower peak (centered ${T_1}=150$ msec) for all SNR but the errors of peak areas were larger in the higher peak than in the lower peak. The CONTIN analysis of the measured relaxation data of phantoms revealed two peaks between 20 and 60 msec and between 500 and 700 msec. The analysis gives the peak area ratio as oil 10%: oil 20%: oil 30% = 1:1.3:1.9, which is different from the exact ratio, 1:2:3. For human brain, in ROI 3 (CSF), only one component of -distributions was observed whereas in ROI 1(GM) and in ROI 2 (WM) we observed two components of ${T_1}-distribution$. For the WM and CSF there was great agreement between the observed ${T_1}-relaxation$ times and the reported values. Conclusion : we demonstrated that the relaxographic method provided additional information such as the distribution of relaxation times and water content, which were not available in the routine relaxometry and ${T_1}/{T_2}$ mapping techniques. In addition, these additional information provided by relaxographic analysis may have clinical importance.

• Investigative Magnetic Resonance Imaging
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• v.16 no.2
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• pp.159-168
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• 2012

The proximity of thoracic aortic aneurysm to the left subclavian artery (LSA) has made the coverage of LSA during thoracic endovascular aortic repair (TEVAR) be essential. Despite controversy concerning the safety of LSA coverage and the indications for LSA revascularizations, the cerebral hemodynamic change after LSA coverage has not been demonstrated. We prospectively examined two patients who would undergo TEVAR with LSA coverage by using 2D cine phase contrast MR imaging. After LSA coverage, the left subclavian steal was properly compensated by the increased flow volumes of both carotid arteries and right vertebral artery, which is the major collateral supply. The total brain supply after TEVAR did not lessen, which showed good correlation with uneventful clinical outcome. Therefore, 2D phase contrast MR imaging can be recommended as a useful technique to evaluate the hemodynamic change of the LSA coverage during TEVAR and to triage the candidate for LSA revascularization.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.961-968
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• 2022

Rotator cuff tears are a leading cause of shoulder pain in adults. Due to the increase in social activities, the number of patients complaining of shoulder pain is increasing, and interest in shoulder diseases is also increasing. With the development of ultrasound equipment, the sensitivity and specificity of diagnosis are high, and it is used to diagnose rotator cuff tears in musculoskeletal disease. Ultrasound is recognized as a complementary method to MRI examination in rotator cuff tears. Therefore, this study aimed to find out the diagnostic usefulness of ultrasound and MRI examinations in the diagnosis of shoulder rotator cuff tears.A retrospective analysis was performed on 262 patients who were diagnosed with final rotator cuff damage by arthroscopy after completing ultrasound and MRI examinations. Sensitivity, feature, positive predictive value, image predictive value, and touch were disassembled for the test results. In addition, the degree of clavicular tear was scored and recorded in 5 stages. Ultrasound examination was similar to MRI examination results for both full-thickness and partial tears, and there was no statistically significant difference. Partial tear test results showed higher positive predictive value and accuracy than MRI test. In conclusion, ultrasound can be fully utilized as a screening test for rotator cuff disease, and it is thought that it will be selected and used clinically according to the patient's constitution and situation.

• Journal of the Korean Society of Radiology
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• v.84 no.1
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• pp.51-74
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• 2023

Multiple myeloma, which is a proliferative disease of plasma cells that originate from a single clone, is the second most common hematologic malignancy following non-Hodgkin lymphoma. In the past, its diagnosis was made based on clinical findings (so-called "CRAB") and a skeletal survey using radiographs. However, since the implementation of the International Myeloma Working Group's revised guideline regarding the radiologic diagnosis of multiple myeloma, whole-body (WB) MRI has emerged to play a central role in the early diagnosis of multiple myeloma. Diffusion-weighted imaging and fat quantification using Dixon methods enable treatment response assessment by MRI. In keeping with the trend, a multi-institutional and multidisciplinary consensus for standardized image acquisition and reporting known as the Myeloma Response Assessment and Diagnostic System (MY-RADS) has recently been proposed. This review aims to describe the clinical application of WB-MRI based on MY-RADS in multiple myeloma, discuss its limitations, and suggest future directions for improvement.

• Investigative Magnetic Resonance Imaging
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• v.13 no.2
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• pp.190-194
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• 2009

Generalized lymphangiomatosis is a rare congenital malformation of the lymphatics. CT and MR scan have been used to evaluate lymphangiomas, which appear as large multicystic fluid-filled masses. CT and MR Imaging findings are often helpful in distinguishing lymphangiomas from various vascular disorders. We report the findings of CT, MRI and bone scan in a patient with generalized cystic lymphangiomatosis. Whole body 3.0-T MR scan using STIR sequence with a larger FOV could detect the additional lesions that were not seen at other imaging modalities. We believe that whole body 3.0 T MR imaging is a good modality to evaluate the extent of the disease and following up the patients with the generalized cystic lymphangiomatosis.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.1 no.2
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• pp.78-85
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• 2008

Purpose: The findings of preoperative magnetic resonance imaging (MRI) and ultrasonography (US) examination in the diagnosis of rotator cuff tear were then compared with the findings of arthroscopic examination, and to evaluate the postoperative integrity of rotator cuff using serial US examination. Methods: Between February and May 2008, 29 patients with rotator cuff tear had undergone preoperative US and MRI examination and subsequent arthroscopic examination. And the results of MRI and US were compared with intra-operative results of the arthroscopic examination. We observed the postoperative integrity of rotator cuff using serial (postoperative 2 weeks, 6 weeks, 3 months) US examination. Results: The sensitivity of US and MRI for identifying rotator cuff tear were 100% and 100%. The sensitivity of US and MRI were 95% and 82% in full thickness tear, and 50%, 33% in partial thickness tear, respectively. Overall accuracy of US and MRI were 86%, 69%. Among 22 patients were operated for full thickness tear, intra-operative gap formation was identified in 11 patients (50%, small to medium 2 cases, large to massive 9 cases) which were identified at 2 weeks postoperative US. We could find 5 re-tears (23%, small to medium 1 case, large to massive 4 cases) on 6 weeks postoperative US after passive range of motion (ROM) exercise, and could also find 7 re-tears (32%, small to medium 2 cases, large to massive 5 cases)on 3 months postoperative US after active ROM exercise. Conclusion: Serial US after arthroscopic rotator cuff repair was useful to differentiate intra-operative gap formation from postoperative re-tear. We found 5 retears (23%) at 6 weeks and 7 retears (32%) at 3 months postoperative US, it was useful to make treatment plan during postoperative rehabilitation.