• Investigative Magnetic Resonance Imaging
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• v.5 no.2
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• pp.138-148
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• 2001

Purpose : Within a clinically acceptable time frame, we obtained the high resolution MR images of the human brain, knee, foot and wrist from 3T whole-body MRI system which was equipped with the world first 37 active shield magnet. Materials and Methods : Spin echo (SE) and Fast Spin Echo (FSE) images were obtained from the human brain, knee, foot and wrist of normal subjects using a homemade birdcage and transverse electromagnetic (TEM) resonators operating in quadrature and tuned to 128 MHz. For acquisition of MR images of knee, foot and wrist, we employed a homemade saddle shaped RF coil. Topical common acquisition parameters were as follows: matrix=$512{\times}512$, field of view (FOV) =20 cm, slice thickness = 3 mm, number of excitations (NEX)=1. For T1-weighted MR images, we used TR = 500 ms, TE = 10 or 17.4 ms. For T2-weighted MR images, we used TR=4000 ms, TE = 108 ms. Results : Signal to noise ratio (SNR) of 3T system was measured 2.7 times greater than that of prevalent 1.5T system. MR images obtained from 3T system revealed numerous small venous structures throughout the image plane and provided reasonable delineation between gray and white matter. Conclusion The present results demonstrate that the MR images from 3T system could provide better diagnostic quali\ulcorner of resolution and sensitivity than those of 1.5T system. The elevated SNR observed in the 3T high field magnetic resonance imaging can be utilized to acquire images with a level of resolution approaching the microscopic structural level under in vivo conditions. These images represent a significant advance in our ability to examine small anatomical features with noninvasive imaging methods.

• Journal of the Korean Society of Radiology
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• v.79 no.6
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• pp.348-353
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• 2018

Hepatic pseudolymphoma is a rare benign liver mass that is characterized by proliferation of non-neoplastic lymphocytes extranodally. To the best of our knowledge, only 46 cases have been reported in the English literature. We described the case of a 75-year-old woman with hepatic pseudolymphoma mimicking a hypervascular tumor. After the histological confirmation of the rectal neuroendocrine tumor, CT scan revealed a 1.0 cm-sized, poorly-defined and low-density nodule in the liver. On MRI, the hepatic nodule showed an arterial enhancement and a low-signal intensity on the hepatobiliary phase. On diffusion-weighted imaging, the hepatic nodule showed a high signal intensity on a high b-value. On fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT, it revealed a high standardized uptake value nodule. The US showed the hypoechoic nodule and the US-guided biopsy confirmed the hepatic pseudolymphoma.

• The Journal of the Korea Contents Association
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• v.13 no.2
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• pp.308-313
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• 2013

In this paper, we measured specific absorption rate (SAR) using characteristic variables such as flip angle, repetition time (TR) and echo time (TE) at magnetic resonance imaging. The subject was applied to same scan technique from body weight 10 kg to 90 kg, were measured for the average SAR and the peak SAR values according to the change of parameter. SAR with different body weight levels was not seen a significant change at TE but it increased in the larger flip angle and the shorter TR. SAR value was within the limits of human head acceptable standard and SNR in segmental body weights was not proportional to the increase of body weights. In conclusion, this study can be helpful for diagnosis by using appropriate parameters which obtained the various contrast and SNR.

• Investigative Magnetic Resonance Imaging
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• v.11 no.1
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• pp.1-9
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• 2007

The obstacles for cardiac imaging are motion artifacts due to cardiac motion, respiration, and blood flow, and low signal due to small tissue volume of heart. To overcome these obstacles, fast imaging technique with ECG gating is utilized. Cardiac exam using MRI comprises of morphology, ventricular function, myocardial perfusion, metabolism, and coronary artery morphology. During cardiac morphology evaluation, double and triple inversion recovery techniques are used to depict myocardial fluidity and soft tissue structure such as fat tissue, respectively. By checking the first-pass enhancement of myocardium using contrast-enhanced fast gradient echo technique, myocardial blood flow can be evaluated. In addition, delayed imaging in 10 - 15 minutes can inform myocardial destruction such as chronic myocardial infarction. Ventricular function including regional and global wall motion can be checked by fast gradient echo cine imaging in quantitative way. MRI is acknowledged to be practical for integrated cardiac evaluation technique except coronary angiography. Especially delay imaging is the greatest merit of MRI in myocardial viability evaluation.

• Journal of the Korean Society of Radiology
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• v.83 no.2
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• pp.439-443
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• 2022

Hibernoma is a rare benign tumor of brown adipose tissue. Herein, we report a case of axillary hibernoma in a 53-year-old female and discuss the various radiologic findings. The US revealed a 4.5-cm well-defined oval heterogenous hyperechoic mass in the right axilla with anterior displacement of the axillary vessels. Non-enhanced chest CT showed a 5.0-cm well defined, oval, and low-attenuated mass. MRI demonstrated a 5.5-cm mass with heterogeneous intermediate-to-high signal intensity on T1-and T2-weighted images and irregular enhancement at the peripheral portion. The patient underwent an US-guided core needle biopsy and the final diagnosis was hibernoma.

• Journal of the Korean Society of Radiology
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• v.82 no.5
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• pp.1334-1340
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• 2021

Amyloidosis has been reported to be associated with non-Hodgkin lymphoma. Amyloidosis and lymphoma can be related in two ways: lymphoma-associated systemic amyloidosis and peritumoral amyloidosis with lymphoma. We report a rare case of peritumoral amyloidosis in a patient with head and neck mucosa-associated lymphoid tissue lymphoma. On CT, the oropharyngeal mass showed an irregularly shaped soft-tissue density with multifocal amorphous calcifications and heterogeneous enhancement. On MRI, the mass showed heterogeneous low signal intensity on both T1- and T2-weighted images. On contrast-enhanced MR images, the mass showed good enhancement with several inner non-enhancing foci. Concurrent pathologies, such as peritumoral amyloidosis, should be considered when calcifications are noted in patients with pre-treatment lymphoma.

• Progress in Medical Physics
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• v.13 no.3
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• pp.120-128
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• 2002

To investigate differences between the metabolic ratios of normal controls and brain tumors such as astrocytomas and glioblastoma multiforme (GM) by proton MR spectroscopy (MRS) at 37 high field system. Using 3T MRI/MRS system, localized water-suppressed single-voxel technique in patients with brain tumors was employed to evaluate spectra with peaks of N-acetyl aspartate (NAA), choline-containing compounds (Cho), creatine/phosphocreatine (Cr) and lactate. On the basis of Cr, these peak areas were quantificated as a relative ratio. The variation of metabolites measurements of the designated region in 10 normal volunteers was less than 10%. Normal ranges of NAA/Cr and Cho/Cr ratios were 1.67$\pm$018 and 1.16$\pm$0.15, respectively. NAA/Cr ratio of all tumor tissues was significantly lower than that of the normal tissues (P=0.005). Cho/Cr ratio of glioblastoma multiforme was significantly higher than that of astrocytomas (P=0.001). Lactate was observed in all tumor cases. The present study demonstrated that the neuronal degradation or loss was observed in all tumor tissues. Higher grade of brain tumors was correlated with higher Cho/Cr ratio, indicating a significant dependence of Cho levels on malignancy of gliomas. This results suggest that clinical proton MR spectroscopy could be useful to predict tumor malignancy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.880-890
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• 2010

The intrasvascular ultrasound (IVUS) imaging technique is used to diagnose cerebrovascular diseases such as stroke. Recently, elasticity imaging methods have been investigated to diagnose blood clots attached to blood vessel intima. However, the IVUS imaging technique is an invasive method that requires a transducer to be inserted into blood vessel. In this paper, strain images are obtained of blood clots attached to blood vessel intima with data acquired from outside the blood vessel using a linear array transducer. In order to measure the displacement of blood vessel accurately, experimental data are acquired by steering ultrasound beams so that they can intersect the blood vessel wall at right angles. The acquired rf data are demodulated to the baseband. The resulting complex baseband signals are then processed by an autocorrelation algorithm to compute the blood vessel movement and thereby produce strain image. This proposed method is verified by experiments on a plastic blood vessel mimicking phantom. The efficacy of the proposed method was verified using a home-made blood vessel mimicking phantom. The blood vessel mimicking phantom was constructed by making a 6 mm diameter hollow cylinder inside it to simulate a blood vessel and adhering 2 mm thick soft plaque to the inner wall of the hollow cylinder. The RF data were acquired using a clinical ultrasound scanner (Accuvix XQ, Medison, Seoul. Korea) with a 7.5 MHz linear array transducer by steering ultrasound beams in steps of $1^{\circ}$ from $-40^{\circ}$ to $40^{\circ}$ for a total of 81 angles. Experimental results show that the plaque region near the blood vessel wall is softer than background tissue. Although the imaging region is restricted due to the limited range of angles for which scan lines are perpendicular to the wall, the feasibility of strain imaging is demonstrated.

• Korean Journal of Psychosomatic Medicine
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• v.26 no.2
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• pp.119-126
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• 2018

Objectives : The aim of this study is to investigate correlation between degree of white matter hyperintensities (WMH) and neurocognitive function along with behavioral and psychological symptoms of dementia (BPSD) in Korean patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI). Methods : Participants were 115 elderly subjects diagnosed with Alzheimer's disease or mild cognitive impairment in this retrospective study. WMH in brain MRI were rated with standardized visual rating scales (Fazekas scales) and the subjects were divided into two groups according to Fazekas scale. Cognitive function was evaluated with Korean version of the consortium to establish a registry for Alzheimer's Disease (CERAD-K), and BPSD was evaluated with Korean neuropsychiatric inventory (K-NPI). Independent t-test was performed to analyze the relationship between the degree of WMH and neurocognitive functions & BPSD. Results : Especially, the group with high severity of WMH showed significantly lower language fluency (p<0.05). In addition, the group with high severity of WMH showed significantly higher score in K-NPI. Conclusions : There was a significant association between WMH and neurocognitive test related with executive function. Moreover, WMH seems to affect BPSD severity. Evaluation of WMH would provide useful information in clinical settings.

• Journal of Veterinary Clinics
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• v.32 no.5
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• pp.464-468
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• 2015

A 6-year-old, intact male maltese was presented with hindlimb ataxia of 4 day duration. Physical and neurological examinations revealed a bright, alert, and responsive dog, with no evidence of cranial nerve deficits, conscious proprioceptive deficits. Spinal reflexes of the hind and forelimbs were normal. Patellar, cranial tibial, and withdrawal reflexes were normal. Pain could not be elicited on manipulation of the neck or palpation of the spinal column. Survey radiographs of the vertebral column were unremarkable. Computed tomography (CT) scans in the transverse plane were performed. The results of CT imaging were unremarkable. Magnetic resonance imaging (MRI) in both sagittal and transverse planes was performed. The extent of the lesion was 25 mm in length by 4 mm in thickness. The spinal cord was deviated ventrally and appreared thinner. On T1-weighted and FLAIR images, a discrete hypointense lesion dorsal to the spinal cord was observed at L1-2 which was contiguous with the subarachnoid space. On T2-weighted images, this region was hyperintense, consistent with a fluid-filled structure. The signal intensity of the cysts was equivalent to cerebrospinal fluid (CSF). Surgical treatment involving dorsal laminectomy had successful outcomes.