• The Academic Congress of Korean Shoulder and Elbow Society
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• 2009.11a
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• pp.29-33
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• 2009

단순촬영에서 견관절을 이루는 골격의 형태를 파악하고 MRI에서는 주로 회전근 개 건의 fraying및 파열, 오훼견봉인대의 견봉 부착부위의 fraying, 점액낭염, 활막염, 관절순의 병변, 연골연화와 같은 연부조직의 병변을 관찰한다. 회전근 개 파열의 고식적 MR 진단은 정확도가 93%, 민감도가 84~100%, 특이도가 88~97%, 지방억제 MR 관절강 조영술은 민감도 및 특이도가 90%및 75%에서 100%까지 최근 보고 되고 있다. 단순촬영검사로 충돌중후군의 일반적인 소견을 파악할 수 있고 impingement series에는 견관절 전후면, suprascapular outlet view (SSO), craniocaudal 30 degree tilt view (CC30T), axillary view를 포함한다. 특히 SSO에서 견봉 및 ACJ의 형태 및 골극의 유무를 파악하고, CC30T에서는 견봉 돌출의 정도를 파악할 수 있다. 최근 고해상도의 MDCT로서 얻은 3차원 영상이 충돌증후군의 전반적인 영상 소견을 파악할 수 있고 수술전 평가에 이용되고 있다. MRI 및 MR Arthrography의 영상은 일반적으로 극상건의 주행에 따른 고식적 MR 사위 관상면이 중요하고 사위 시상면에서 견봉돌기의 형태와 대결절에 부착되는 극상건의 파열 유무와 정도를 파악할 수 있다. MR 관절조영술 후 외전 및 외회전후 (ABER view)의 영상도 관절면 쪽으로 부분 파열된 극상건의 진단에 유용하다.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.143-143
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• 2001

목적： 현재 3.0T MRI system은 세계적으로 개발이 진행되고 있는 가운데, 3.0T에서 사용할 수 있는 RF coil의 개발이 시급한 상황이다. 1.0T 및 1.5T MRI 와는 달리 3.0T에서 사용할 수 있는 Body coil 및 그에 따른 High power RF amplifier 제작에 많은 제약이 있다. 작은 용량의 RF amplifier를 이용하여 신체의 부분을 촬영 하고자 한다면, Tx/Rx 가능한 coil을 이용하면 가능할 것이다. 이러한 이유로 본 연구에서는 Tx/Rx 가능한 Quadrature type C-spine RF coil을 설계, 제작하여 3.0T 고자장 자기공명 영상장치에서의 임상진단 활용범위를 확대하였다.

• Journal of the Korean Society of Radiology
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• v.85 no.1
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• pp.252-252
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• 2024

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.37-44
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• 2002

신경계의 MR영상은 하드웨어적인 발달과 초고속 영상 기법으로 기존의 MRI가 제공해 줄 수 있는 해부학적 정보 외에 기능적인 정보인 물의 확산, 뇌 혈류 정보, 뇌의 기능적 지도화와 뇌대사물의 농도를 측정할 수 있게 되었다. 반전회복영상(Inversion Recovery), 확산(diffusion), 관류(profusion), 기능적(functional)영상, 뇌의 3차원 뇌표면 rendering 및 곡면재구성영상의 임상적인 의의를 알아보고자 한다.

• Investigative Magnetic Resonance Imaging
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• v.2 no.1
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• pp.14-30
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• 1998

Manganese is an essential element in the body. It is mainly deposited in the liver and to a lesser degree in the basal ganglia of the brain and eliminated through the bile duct. Rapid turnover of managanese in the body makes it difficult to evaluate the manganese exposure in workers, esecially in those with irregular or intermittent exposure, like welders. Therefore, conventional biomarkers, including blood and urine manganese can provide only a limited information about the long-tern or cumulative exposure to manganese. Introduction of magnetic resonance imaging (MRI) made a progress in the assessment of manganese exposure in the medical conditions related to manganese accumulation, e. g. hepatic failure and long-term total parenteral nutrition. Manganese shortens spin-lattice(T1) relaxation time on MRI due to its paramagnetic property, resulting in high signal intensity (HSI) on T1-weighted image(T1W1) of MRI. Manganese deposition in the brain, therefore, can be visualizedas an HSI in the globus pallidus, the substantia nigra, the putamen and the pituitary. clinical and epidemiologic studies regarding the MRI findings in the cases of occupational and non-occupational manganese exposure were reviewed. relationships between HSI on T1W1 of MRI and age, gender, occupational manganese exposure, and neurological dysfunction were analysed. Relationships betwen biological exposure indices and HSI on MRE werealso reviewed. Literatures were reviewed to establish the relationships between HSI, Manganese deposition in the brain, pathologic findings, and neurological dysfunction. HSI on T1W1 of MRI reflects regional manganese deposition in the brain. This relationship enables an estimation of regional manganese deposition in the brain by analysing MR signal intensity. Manganese deposition in the brain can induce a neuronal loss in the basal ganglia but functional abnormality is supposed to be related to the cumulative exposure of manganese in the brain, use of brain MRI for the assessment of exposure in a group of workers seems to be hardly rationalized, while ti can be a useful adjunct for the evaluation of manganese exposure int he cases with suspected manganese-related health problems.

• The Korean Journal of Nuclear Medicine
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• v.36 no.4
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• pp.232-243
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• 2002

Purpose: We studied whether brain perfusion SPECT is useful in the psychiatric disability evaluation of patients with chronic traumatic brain injury (TBI). Materials and Methods: Sixty-nine patients (M:F=58:11, age $39{\pm}14$ years) who underwent Tc-99m HMPAO brain SPECT, brain MRI and neuropsychological (NP) tests during hospitalization in psychiatric wards for the psychiatric disability evaluation were included; the severity of injury was mild in 31, moderate in 17 and severe in 21. SPECT, MRI, NP tests were peformed $6{\sim}61$ months (mean 23 months) post-injury. Diagnostic accuracy of SPECT and MRI to show hypoperfusion or abnormal signal intensity in patients with cognitive impairment represented by NP test results were compared. Results: Forty-two patients were considered to have cognitive impairment on NP tests and 27 not. Brain SPECT showed 71% sensitivity and 85% specificity, while brain MRI showed 62% sensitivity and 93% specificity (p>0.05, McNemar test). SPECT found more cortical lesions and MRI was superior in detecting white matter lesions. Sensitivity and specificity of 31 mild TBI patients were 45%, 90% for SPECT and 27%, 100% for MRI (p>0.05, McNemar test). Among 41 patients with normal brain MRI, SPECT showed 63% sensitivity (50% for mild TBI) and 88% specificity (85% for malingerers). Conclusion: Brain SPECT has a supplementary role to neuropsychological tests in the psychiatric disability evaluation of chronic TBI patients by detecting more cortical lesions than MRI.

• Investigative Magnetic Resonance Imaging
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• v.11 no.2
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• pp.95-102
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• 2007

Purpose: To acquire high-resolution spiral-scan images at higher magnetic field, high homogeneous magnetic field is needed. Field inhomogeneity mapping and in-vivo shimming are important for rapid imaging such as spiral-scan imaging. The rapid scanning sequences are very susceptible to inhomogeneity. In this paper, we proposed a higher-order shimming method to obtain homogeneous magnetic field. Materials and Methods: To reduce measurement time for field inhomogeneity mapping, simultaneous axial/ sagittal, and coronal acquisitions are done using multi-slice based Fast Spin echo sequence. Acquired field inhomogeneity map is analyzed using the spherical harmonic functions, and shim currents are obtained by the multiplication of the pseudo-inverse of the field pattern with the inhomogeneity map. Results: Since the field inhomogeneity is increasing in proportion to the magnetic field, higher order shimming to reduce the inhomogeneity becomes more important in high field imaging. The shimming technique in which axial, sagittal, and coronal section inhomogeneity maps are obtained in one scan is developed, and the shimming method based on the analysis of spherical harmonics of the imhomogenity map is applied. The proposed technique is applicable to a localized shimming as well. High resolution spiral-scan imaging was successfully obtained with the proposed higher order shimming. Conclusion: Proposed pulse sequence for rapid measurement of inhomogeneity map and higher order shimming based on the inhomogeneity map work very well at 3 Tesla MRI system. With the proposed higher order shimming and localized higher order shimming techniques, high resolution spiral-scan images are successfully obtained at 3 T MRI system.

• Journal of the Korean Society of Radiology
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• v.83 no.3
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• pp.620-631
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• 2022

Purpose This study aimed to investigate the diagnostic performance of features suggestive of nodal metastasis on preoperative MRI in patients with invasive breast cancer. Materials and Methods We retrospectively reviewed the preoperative breast MRI of 192 consecutive patients with surgically proven invasive breast cancer. We analyzed MRI findings of axillary lymph nodes with regard to the size, long/short ratio, cortical thickness, shape and margin of the cortex, loss of hilum, asymmetry, signal intensity (SI) on T2-weighted images (T2WI), degree of enhancement in the early phase, and enhancement kinetics. Receiver operating characteristic (ROC) analysis, chi-square test, t test, and McNemar's test were used for statistical analysis. Results Increased shorter diameter, uneven cortical shape, increased cortical thickness, loss of hilum, asymmetry, irregular cortical margin, and low SI on T2WI were significantly suggestive of metastasis. ROC analysis revealed the cutoff value for the shorter diameter and cortical thickness as 8.05 mm and 2.75 mm, respectively. Increased cortical thickness (> 2.75 mm) and uneven cortical shape showed significantly higher sensitivity than other findings in McNemar's test. Irregular cortical margins showed the highest specificity (100%). Conclusion Cortical thickness > 2.75 mm and uneven cortical shape are more sensitive parameters than other findings, and an irregular cortical margin is the most specific parameter for predicting axillary metastasis in patients with invasive breast cancer.

• Journal of the Korean Society of Radiology
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• v.83 no.5
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• pp.1160-1167
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• 2022

Epipericardial fat necrosis (EPFN) is a relatively rare cause of acute chest pain, with only five pediatric cases having been reported in the English-language medical literature to date. EPFN can be diagnosed based on the clinical symptoms of acute pleuritic chest pain and classic CT features of typically ovoid fatty lesions surrounded by a rim or capsule in the mediastinal or pericardial areas. Previous studies have reported that contrast-enhanced MRI can detect typical fat signal changes in adults with EPFN. We report a pediatric EPFN case diagnosed using gadolinium-enhanced MRI. Thus, contrast-enhanced MRI may be used to confirm EPFN in the differential diagnoses of the causes of acute chest pain.

• Journal of the Korean Society of Radiology
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• v.81 no.5
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• pp.1194-1203
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• 2020

Purpose To evaluate the diagnostic utility of the stalk and the inchworm sign on preoperative MRI for detecting superficial bladder cancers, and to compare the diagnostic performance between the stalk and the inchworm sign. Materials and Methods We retrospectively reviewed 240 patients (505 tumors) who had undergone radical cystectomy. The tumors were classified as follows: superficial or invasive tumors indicated by the stalk or inchworm sign on 3.0 Tesla MRI. We evaluated the diagnostic accuracy of the stalk and inchworm signs, by comparing each finding with the postoperative pathologic T stage. We compared diagnostic performance between them statistically. Results The stalk and inchworm signs showed high specificity (93% and 91%, respectively), positive predictive values (89% and 90%, respectively), and acceptable accuracy (70% and 74%, respectively), but low sensitivity (54% and 61%, respectively) and negative predictive values (60% and 63%, respectively). There was no statistically significant difference between the two signs (p > 0.05). Conclusion Superficial bladder cancers could be differentiated from invasive tumors using the stalk or inchworm sign on MRI.