• Investigative Magnetic Resonance Imaging
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• v.22 no.4
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• pp.249-253
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• 2018

Superficial siderosis of the central nervous system (CNS) is a progressive and debilitating neurological disease manifesting sensorineural hearing loss, cerebellar ataxia, and pyramidal tract signs. Chronic extravasation of blood into the subarachnoid space results in the accumulation of hemoglobin derivate in the subpial layer of the CNS, which is toxic to the neural tissues. Craniopharyngioma is a benign third ventricle tumor, which rarely presents with tumor bleeding. We report a rare case of superficial siderosis associated with craniopharyngioma with intratumoral hemorrhage in a patient with no history of prior trauma or CNS surgery.

• Journal of Biomedical Engineering Research
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• v.25 no.3
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• pp.183-188
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• 2004

Magnetic resonance current density imaging (MRCDI) is a useful method for measuring electrical current density distribution inside an object. To avoid object rotations during the conventional MRCDI scans, we have reconstructed current density component images by applying a spatial filter to the magnetic field data measured both inside and outside the object. To measure the magnetic field outside the object with MRI, we immersed the object in a water tank. To evaluate accuracy of the current density imaging, we have made a conductivity phantom with a corresponding finite element method model. We have compared the experimentally obtained current density images with the ones calculated by the finite element method. The average errors of the reconstructed current density images were 6.6 ∼ 45.4 ％ when the injected currents were 1 ∼ 24 mA. We expect that the current density component imaging technique can be used in diverse biomedical applications such as electrical therapy system developments and biological electrical safety analysis.

• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.132-138
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• 2007

MR(magnetic resonance) image of moving organ such as heart shows serious distortion of MR image due to motion itself. To eliminate motion artifacts, MRI(magnetic resonance imaging) scan sequences requires a trigger pulse like ECG(electro-cardiography) R-wave. ECG-gating using cardiac cycle synchronizes the MRI sequence acquisition to the R-wave in order to eliminate image motion artifacts. In this paper, we designed ECG/PPG(photo-plethysmography) gating system which is for eliminating motion artifacts due to moving organ. This system uses nonmagnetic carbon electrodes, lead wire and shield case for minimizing RF(radio-frequency) pulse and gradient effect. Also, we developed a ECG circuit for preventing saturation by magnetic field and a finger plethysmography sensor using optic fiber. And then, gating pulse is generated by adaptive filtering based on NLMS(normalized least mean square) algorithm. To evaluate the developed system, we measured and compared MR imaging of heart and neck with and without ECG/PPG gating system. As a result, we could get a clean image to be used in clinically. In conclusion, the designed ECG/PPG gating system could be useful method when we get MR imaging of moving organ like a heart.

• The Journal of Korean Medicine
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• v.17 no.1 s.31
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• pp.171-189
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• 1996

Background and Purpose: The greater part of patients to visit Hospital of Oriental Medicine suffer from cerebrovascular accident(CVA). There is transcranial Doppler(TCD) in the diagnostic method to confirm cerebrovascular accident(CVA). Transcranial Doppler(TCD) is an accurate method of monitoring the blood flow velocities of the cerebral vessels and have been generally used to prevent symptomatic vasospasm and confirm cerebral infarction. So we studied, in the crebrovascular accident(CVA), to estimate whether transcranial Doppler(TCD) is useful to. Methods: Using transcranial doppler(Multigon Model 500M Transcranial Doppler System), we measured the mean and peak velocity and the direction of blood flow in 10 cerebrovascular accident(CVA)'s subjects who had been examined by Computed Tomography(CT) or Magnetic Resonance Imaging (MRI). Results : As an anticipation, in cerebrovascular accident(CVA)'s subject with Cb-infarction, the mean and peak velocity of blood flow fell down remarkably and the direction of blood flow was change or irritable. But didn't find out any signal in lacunar infarction. Also, in case with spontaneous hemorrhage, the velocity and direction of blood flow was change but this signal was short of diagnosis for Cb-hemorrhage. Besides, we found signals about embolism, stenosis, thrombosis and occlusion in cerebrovascular accident(CVA)'s subjects. Conclusion: In Cb-infarction, the result of TCD was equal to diagnosis with Computed Tomography(CT) or Magnetic Resonance Imaging (MRI). But about lacunar infarction or spontaneous hemorrhage, signals of TCD couldn't be found out or was insufficient more than Computed Tomography(CT) or Magnetic Resonance Imaging(MRI). In cerebrovascular accident(CVA)'s subject with embolism, stenosis, thrombosis or occlusion, signals of TCD were found out more than Computed Tomography(CT) or Magnetic Resonance Imaging(MRI). Therefore transcranial doppler(TCD) is necessary method which makes a diagnosis of cerebrovascular accident(CVA), with Computed Tomography(CT) or Magnetic Resonance Imaging(MRI).

• Investigative Magnetic Resonance Imaging
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• v.19 no.1
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• pp.10-18
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• 2015

Background and Purpose: The association between the low emotional regulation and the brain structural change of major depressive disorder (MDD) has been proposed, but the voxel-based morphometry (VBM) studies on female MDD are rare. The purpose of the present study was to show the regional volume changes of gray matter (GM) in female patients with MDD by optimized VBM. Methods: To control subjects homogeneity, twenty female MDD patients and age, sex matched 21 normal controls were included for the VBM analysis. To identify the change of regional gray matter volume (GMV), the optimized VBM was performed with T1 MRIs. The amounts of gray/white matter and intracranial cavity volumes (ICV) were measured. The analysis of covariance (ANCOVA) and partial correlation analyses covariate with age and ICV were applied for VBM. Results: The age and ICV distributions were similar between the two groups. In the ANCOVA, the total GMV of MDD was smaller than that of normal controls. In the VBM, regional GMV was relatively decreased in the limbic system (amygdalae, ambient gyri, hippocampi heads, subiculum, posterior parahippocampal gyri, pulvinar nuclei, dorsal posterior cingulate gyri, and left pregenual cingulate gyrus). The lingual gyri, short insular gyri, right fusiform gyrus, and right inferior frontal gyrus were also showed decreased regional GMV. Conclusion: The results of this study indicate that the female MDD is mainly associated with the structural deficits of the limbic system and limbic system related cortices, which were known to the center of emotions.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.421-430
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• 2000

This paper describes an optimal design method which is applied a weighted least square (WLS) method for Magnetic Resonance Imaging (MRI) system. An optimal design approach is presented for a homogeneity superconducting magnet with the superconducting active shield especially for a magnetic resonance imaging system. The WLS is used to obtain the optimal configurations using the least amount and minimum volume of conductor, exhibiting the smallest level of field inhomogeneity and resulting in the least level of stray field. The proposed model is used to design a multiple-shield configuration for a 1.5 T MRI magnet. The field homogeneity is required less than 5 gauss stray field contour within 4m axially and 3m radially from origin. The designed magnet with the actively magnetic shielding coil out of main coils is analyzed by FEM and theoretical analysis method, investigated the field homogeneity.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.63-71
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• 2008

• Korean Journal of Radiology
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• v.23 no.6
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• pp.625-637
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• 2022

With regard to the indolent clinical characteristics of prostate cancer (PCa), the more selective detection of clinically significant PCa (CSC) has been emphasized in its diagnosis and management. Magnetic resonance imaging (MRI) has advanced technically, and recent international cooperation has provided a standardized imaging and reporting system for prostate MRI. Accordingly, prostate MRI has recently been investigated and utilized as a triage tool before biopsy to guide tissue sampling to increase the detection rate of CSC beyond the staging tool for patients in whom PCa was already confirmed on conventional systematic biopsy. Radiologists must understand the current paradigm shift for better PCa diagnosis and management. This article reviewed the recent literature, demonstrating the diagnostic value of pre-biopsy prostate MRI with targeted biopsy and discussed unsolved issues regarding the paradigm shift in the diagnosis of PCa.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.314-324
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• 1996

A high speed NMR quality evaluation sensor was designed , constructed and tested . The device consists of an NMR spectrometer coupled to a conveyor system. The conveyor was run at speeds ranging from 0 to 250 mm/s. Spectral of avocado fruits and one-dimensional magnetic resonance images of pickled olives were acquired while the samples were moving on a conveyor belt mounted through a 20Tesla NMR magnet with a 20 mm diameter surface coil and a 150 mm diameter imaging coil respectively. Fro a magnetic resonance spectrum analysis, motion through variations in the magnetic field tends to narrow spectral line width just like using sample rotation in high resolution NMR to narrow spectral line width. Spectrum analysis was used to detect the dry weight of avocado fruits using the ratio oil and water resonance peaks. Good correlations maximum r=0.970@ 50 mm/s and minimum r=0.894@250mm/s ) between oil and water resonance peak ratio and dry weight of avocados were observed at speeds ra ging from0 to 250mm/s. For the application of magnetic resonance imaging (MRI) method, the projections were used to distinguish between pitted and non-pitted olives . Effect of fruit position in the coil was tested and coil degree effects were noticed when projects were generated under dynamic conditions. Various belt speeds (up to 250mm/s) were tested and detection results were compared to static measurements. Higher classification errors were occurred at dynamic conditions compared to errors while olives were at rest.

• Journal of Biomedical Engineering Research
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• v.17 no.4
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• pp.525-534
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• 1996

We have developed a fast steady state free precession interferometry (SSFPI) technique which is useful for the fMRl (functional Magnetic Resonance Imaging). As is known, SSFP sequence with a suitable adjustment of Vadient (readeut) allows us to measure precession angle 6 which in tw relates to the field inhomogeneity. Combining the two pulses (known as FID and Echo) in FADE (Fast Acquisition Double Echo) sequence, for example, one can obtain the interference term which is directly related to the precession angle It has been known that a fast high resolution magnetic field mapping is possible by use of the modified FADE sequence or SSFPI, and we have attempted to use the SSFPI technique for the susceptibility-induced fMRl. When the method is applied to the susceptibility effect based functional magnetic resonance imaging (fMRl), it was found that the direct susceptibility effect measurement was possible without perturbations such as the backgrounds and inflow effect. In this paper, simulation results and experimental results obtained with 2.0 Tesla MRI system are presented.