• Investigative Magnetic Resonance Imaging
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• v.24 no.3
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• pp.141-153
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• 2020

Purpose: Myocardial T1 and T2 relaxation times are affected by technical factors such as cardiovascular magnetic resonance platform/vendor. We aimed to validate T1 and T2 mapping sequences using a phantom; establish reference T1, T2, and extracellular volume (ECV) measurements using two sequences at 3T in normal Koreans; and compare the protocols and evaluate the differences from previously reported measurements. Materials and Methods: Eleven healthy subjects underwent cardiac magnetic resonance imaging (MRI) using 3T MRI equipment (Verio, Siemens, Erlangen, Germany). We did phantom validation before volunteer scanning: T1 mapping with modified look locker inversion recovery (MOLLI) with 5(3)3 and 4(1)3(1)2 sequences, and T2 mapping with gradient echo (GRE) and TrueFISP sequences. We did T1 and T2 mappings on the volunteers with the same sequences. ECV was also calculated with both sequences after gadolinium enhancement. Results: The phantom study showed no significant differences from the gold standard T1 and T2 values in either sequence. Pre-contrast T1 relaxation times of the 4(1)3(1)2 protocol was 1142.27 ± 36.64 ms and of the 5(3)3 was 1266.03 ± 32.86 ms on the volunteer study. T2 relaxation times of GRE were 40.09 ± 2.45 ms and T2 relaxation times of TrueFISP were 38.20 ± 1.64 ms in each. ECV calculation was 24.42% ± 2.41% and 26.11% ± 2.39% in the 4(1)3(1)2 and 5(3)3 protocols, respectively, and showed no differences at any segment or slice between the sequences. We also calculated ECV from the pre-enhancement T1 relaxation time of MOLLI 5(3)3 and the post-enhancement T1 relaxation time of MOLLI 4(1)3(1)2, with no significant differences between the combinations. Conclusion: Using phantom-validated sequences, we reported the normal myocardial T1, T2, and ECV reference values of healthy Koreans at 3T. There were no statistically significant differences between the sequences, although it has limited statistical value due to the small number of subjects studied. ECV showed no significant differences between calculations based on various pre- and post-mapping combinations.

• Journal of Acupuncture Research
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• v.20 no.3
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• pp.194-208
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• 2003

Objective : Recently, many studies have showed the evidences of the effect of acupuncture treatment through scientific methods. We performed electro-acupuncture on Taixi(K3) and observed the change of brain activity using fMRI. Methods : To see the effect of electro-acupuncture stimulation on Taixi(K3), the experiment was carried out on twelve healthy volunteers, using the gradient echo sequence with the 3.0T whole-body fMRI system(ISOL). After the needle insertion on K3, 2 Hz of electric stimulation was given for 30 seconds, repeated five times, with 30 seconds' intervals. Result & Conclusions : Unilateral electro-acupuncture stimulation on K3 increased the brain activity in Brodman Area 8, 6, 9, 13, 21, 22, 38, 40, 43, 2, 5, 10, 20, 24, 32, 34, 37, 39, 41, 42. and decreased the brain activity in Brodman Area 9, 13, 38, 22, 31, 3, 6, 10, 21, 25, 29, 30. Group Averaged Brain activity induced by Unilateral Electro-acupuncture Stimulation on K3 was increased in Brodman Area 10, 22, 42, 43, 44 and was decreased inn Brodman Area 6 and pyrogen test of Bee venom. Bilateral electro-acupuncture stimulation on k3 increased the brain activity in Brodman Area 22, 3, 19, 4, 13, 17, 21, 41, 42, 2, 5, 6, 7, 18, 23, 29, 30, 31, 40 and decreased the brain activity in Brodman Area 18, 6, 39, 4, 13, 2, 10, 19, 36, 40, 45, 46, 47. Group Averaged Brain activity induced by Bilateral Electro-acupuncture Stimulation on K3 was increased in Brodman Area 22, 13, 4, 3, 29, 38, 43 and was decreased in Brodman Area 18, 3, 19, 22, 39. Motor Stimulation activated Brodmann Area 6, 43, 18.

• Investigative Magnetic Resonance Imaging
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• v.19 no.1
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• pp.31-36
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• 2015

Purpose: To compare the depiction of brain metastases on contrast-enhanced images with 7.0 tesla (T) and at 1.5T MRI. Materials and Methods: Four consecutive patients with brain metastases were scanned on 7.0T whole-body scanner and 1.5T MRI. A 3D T1-weighted gradient echo sequence (3D T1-GRE) at 1.5T (voxel size = $0.9{\times}0.9{\times}1.5mm^3$ after double-dose, gadoterate meglumine, Gd-DOTA) was compared to a 7.0T 3D T1-GRE sequence (voxel size = $0.4{\times}0.4{\times}0.8mm^3$, single-dose Gd-DOTA) in four patients after a 5 minute delay. The number of contrast-enhancing metastases in MPRAGE images was compared in each patient by two radiologists in consensus. We measured contrast ratio of enhancing brain metastases and white matter in 1.5T and 7.0T. Results: In all four patients 7.0T 3D T1-GRE images after single-dose Gd-DOTA and 1.5T after double-dose Gd-DOTA depicted 11 brain metastases equally. In the quantitative analysis of contrast ratios of enhancing brain metastases and white matter, the 1.5T 3D T1-GRE after double-dose showed an increased contrast ratio compared to 7.0T 3D T1-GRE after single-dose ($0.961{\pm}0.571$ versus $0.885{\pm}0.494$; n = 11 metastases). But this difference was not statistically significant (P = 0.711). Conclusion: Our preliminary results indicate that 7.0T single-dose Gd-enhanced images were not different to 1.5T double-dose Gd-enhanced images for the detection of brain metastases.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.876-880
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• 1999

The surfactant self-diffusion coefficients of mixed micellar solutions of ionic and nonionic surfactants have been measured by the NMR pulsed field gradient spin echo(FT-PGSE) method. In addition, the line widths of $^1H$ NMR signal have been monitored. The system investgated are $C_{12}EO_5/SDS/D_2O$, $C_{12}EO_5/DTAC/D_2O$, and $C_{12}EO_8/SDS/D_2O$. In the sample series, the molar ratios of $D_2O$ to surfactant(ionic+nonionic) were kept constant while the surfactant mixing ratio was varied. For the $C_{12}EO_5$ system, the surfactant self-diffusion coefficient indicates minimum when the surfactant mixing ratio is about 20% ionic surfactant. The observed decrease in self-diffusion coefficients as nonionic surfactant was replaced by ionic surfactant is interpreted to mainly be due to an increased micelle-micelle repulsion. The increase in self-diffusion coefficients occurring at higher fraction of ionic surfactant is shown to be due to a decrease in micelle size. For the $C_{12}EO_8$ system, the effect of the surfactant mixing ratio is much weaker which can be understood by considering the molecular geometry and large headgroup area. The proton NMR line widths correlate well with the self-diffusion coefficients and broadening of the alkyl chain methylene signals is found when the self-diffusion coefficients is low.

• The Korean Journal of Nuclear Medicine
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• v.37 no.3
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• pp.162-170
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• 2003

The probabilistic anatomical maps are used to localize the functional neuro-images and morphological variability. The quantitative indicator is very important to inquire the anatomical position of an activated legion because functional image data has the low-resolution nature and no inherent anatomical information. Although previously developed MNI probabilistic anatomical map was enough to localize the data, it was not suitable for the Korean brains because of the morphological difference between Occidental and Oriental. In this study, we develop a probabilistic anatomical map for Korean normal brain. Normal 75 blains of T1-weighted spoiled gradient echo magnetic resonance images were acquired on a 1.5-T GESIGNA scanner. Then, a standard brain is selected in the group through a clinician searches a brain of the average property in the Talairach coordinate system. With the standard brain, an anatomist delineates 89 regions of interest (ROI) parcellating cortical and subcortical areas. The parcellated ROIs of the standard are warped and overlapped into each brain by maximizing intensity similarity. And every brain is automatically labeledwith the registered ROIs. Each of the same-labeled region is linearly normalize to the standard brain, and the occurrence of each legion is counted. Finally, 89 probabilistic ROI volumes are generated. This paper presents a probabilistic anatomical map for localizing the functional and structural analysis of Korean normal brain. In the future, we'll develop the group specific probabilistic anatomical maps of OCD and schizophrenia disease.

• Investigative Magnetic Resonance Imaging
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• v.20 no.2
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• pp.105-113
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• 2016

Purpose: Susceptibility vessel sign (SVS) on gradient echo image, which is caused by MR signal loss due to arterial thrombosis, has been reported in acute middle cerebral artery (MCA) infarction. However, the reported sensitivity and diagnostic accuracy of SVS have been variable. Susceptibility-weighted imaging (SWI) is a newly developed MR sequence. Recent studies have found that SWI may be useful in the field of cerebrovascular diseases, especially for detecting the presence of prominent veins, microbleeds and the SVS. The purpose of this study was to evaluate the diagnostic values of SWI for the detection of hyperacute MCA occlusion. Materials and Methods: Sixty-nine patients (37 males, 32 females; 46-89 years old [mean, 69.1]) with acute stroke involving the MCA territory underwent MR imaging within 6 hours after the symptom onset. MR examination included T2, FLAIR (fluid-attenuated inversion recovery), DWI, SWI, PWI (perfusion-weighted imaging), contrast-enhanced MR angiography (MRA) and contrast-enhanced T1. Of these patients, 28 patients also underwent digital subtraction angiography (DSA) within 2 hours after MR examination. Presence or absence of SVS on SWI was assessed without knowledge of clinical, DSA and other MR imaging findings. Results: On MRA or DSA, 34 patients (49.3%) showed MCA occlusion. Of these patients, SVS was detected in 30 (88.2%) on SWI. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of SWI were 88.2%, 97.1%, 96.8%, 89.5% and 92.8%, respectively. Conclusion: SWI was sensitive, specific and accurate for the detection of hyperacute MCA occlusion.

• Korean Journal of Ecology and Environment
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• v.54 no.4
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• pp.384-389
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• 2021

This study was conducted on October 23, 2020 at the Cheongpyeong Reservoir located in Seorakmyeon, Gapyeong-gun, Gyeonggi-do, and analyzed the horizontal and vertical distribution patterns of fish based on data obtained using fishfinder. The total surface area of fishfinder survey conducted was 782,853 m², and where the water depth (WD) ranges from 10 m to 12 m is widest which 31.7% of total surface area. As a result of the heat map analysis, fish density was highest at right bank under the Gapyeong-bridge, but there was no specific pattern in horizontal distribution of fish. As a result of vertical distribution of fish analysis, 86.6% of fishes are observed at below 6 m of the fish depth (FD, distance from water surface to fish). As a result of the relative height (RH, water depth-distance from bottom to fish ratio) analysis, there was a tendency that fishes are distributed in near surface area more as the WD increased. This tendency could have various reasons such as water temperature gradient along the water depth, and further studies are required for detailed explanation.

• Investigative Magnetic Resonance Imaging
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• v.8 no.1
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• pp.32-41
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• 2004

Purpose : To measure the NMR relaxation properties of MnPC, to observe the characteristics of liver enhancement patterns on MR images in experimentally implanted rabbit VX2 tumor model, and to estimate the possibility of tissue specific contrast agent for MnPC in comparison with the hepatobiliary agent. Materials and Methods : Phthalocyanine (PC) was chelated with paramagnetic ions, manganese (Mn). 2.01 g (5.2 mmol) of phthalocyanine was mixed with 0.37 g (1.4 nlmol) of Mn chloride at $310^{\circ}C$ for 36 hours and then purified by chromatography ($CHCl_3:\;CH_3OH=98:2$, volume ratio) to obtain 1.04 g $(46\%)$ of MnPC (molecular weight = 2000 daltons). The T1/T2 relaxivity (R1/R2) for MnPC were determined at a 1.5 T (64 MHz) MR spectrometer. VX2 tumor model was experimentally implanted in the liver parenchyma of rabbits. All MR studies were performed on 1.5 T. The human extremity radio frequency coil of a bird cage type was employed. MR images were acquired at 17 to 24 days after VX2 carcinoma implantation.4 mmol/kg MnPC and 0.01 mmol/kg Mn-DPDP were injected via the ear vein of rabbits. T1-weighted images were obtained with spin-echo (TR/TE=516/14 msec) and fast multiplanar spoiled gradient recalled (TR/TE : 80/4 msec, $60^{\circ}$ flip angle) pulse sequence. Fast spin-echo (TR/TE=1200/85 msec) was used to obtain the T2-weighted images. Results : The value of T1/T2 relaxivity (R1/R2) of MnPC was $7.28\;mM^{-1}S^{-1}$ and $55.56\;mM^{-1}S^{-1}$ respectively at 1.5 T (64 MHz). Because the T2 relaxivity of MnPC that bonded strongly, covalently manganese with phthalocyanine was very high, the signal intensity of liver parenchyma was decreased on postcontrast T2-weighted images and we could easily distinguish the VX2 carcinoma within the liver parenchyma. When MnPC was administrated intravenously, the tumor margin delineation was more remarkable than Mn-DPDP-enhanced images. The enhancement of liver parenchyma with MnPC persisted at relatively high levels over at least one hour after injection of the contrast agents. Conclusion : The hepatic uptake and biliary excretion of MnPC, which are similar to Mn-DPDP, suggest that this agent is a new liver-specific agent. Also, MnPC seems to be used as a dual contrast agent (T1 and T2) with high T2 relaxivity. However, it is warranted that MnPC needs further investigation as a potential contrast agent for MR imaging of the liver. That is, further characterizations of MnPC are needed in vivo and in vitro before clinical trials. The diagnostic potential of MnPC will also have to be examined more in the animal models of additional types.

• Investigative Magnetic Resonance Imaging
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• v.22 no.1
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• pp.1-9
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• 2018

Purpose: This study was designed to optimize the flip angle (FA) and scan timing of the hepatobiliary phase (HBP) using the 3D T1-weighted, gradient-echo (GRE) imaging with controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique on gadoxetic acid-enhanced 3T liver MR imaging. Materials and Methods: Sixty-two patients who underwent gadoxetic acid-enhanced 3T liver MR imaging were included in this study. Four 3D T1-weighted GRE imaging studies using the CAIPIRINHA technique and FAs of $9^{\circ}$ and $13^{\circ}$ were acquired during HBP at 15 and 20 min after intravenous injection of gadoxetic acid. Two abdominal radiologists, who were blinded to the FA and the timing of image acquisition, assessed the sharpness of liver edge, hepatic vessel clarity, lesion conspicuity, artifact severity, and overall image quality using a five-point scale. Quantitative analysis was performed by another radiologist to estimate the relative liver enhancement (RLE) and the signal-to-noise ratio (SNR). Statistical analyses were performed using the Wilcoxon signed rank test and one-way analysis of variance. Results: The scores of the HBP with an FA of $13^{\circ}$ during the same delayed time were significantly higher than those of the HBP with an FA of $9^{\circ}$ in all the assessment items (P < 0.01). In terms of the delay time, images at the same FA obtained with a 20-min-HBP showed better quality than those obtained with a 15-min-HBP. There was no significant difference in qualitative scores between the 20-min-HBP and the 15-min-HBP images in the non-liver cirrhosis (LC) group except for the hepatic vessel clarity score with $9^{\circ}$ FA. In the quantitative analysis, a statistically significant difference was found in the degree of RLE in the four HBP images (P = 0.012). However, in the subgroup analysis, no significant difference in RLE was found in the four HBP images in either the LC or the non-LC groups. The SNR did not differ significantly in the four HBP images. In the subgroup analysis, 20-min-HBP imaging with a $13^{\circ}$ FA showed the highest SNR value in the LC-group, whereas 15-min-HBP imaging with a $13^{\circ}$ FA showed the best value of SNR in the non-LC group. Conclusion: The use of a moderately high FA improves the image quality and lesion conspicuity on 3D, T1-weighted GRE imaging using the CAIPIRINHA technique on gadoxetic acid, 3T liver MR imaging. In patients with normal liver function, the 15-min-HBP with a $13^{\circ}$ FA represents a feasible option without a significant decrease in image quality.

• Investigative Magnetic Resonance Imaging
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• v.7 no.1
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• pp.22-30
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• 2003

Purpose : The efficacy of magnetic resonance imaging for evaluating coronary artery disease has been reported. In this study, we evaluated the usefulness of breath-hold segmented K-space cine MR imaging for evaluating the patency of coronary artery bypass grafts (CABG). Materials and Method s : Thirty eight patients with a total of 92 CABGs (36 internal thoracic arteries and 56 saphenous vein grafts) were evaluated using segmented K-space cardiac-gated fast gradient echo sequence (2D-FASTCARD) MR imaging. MR magnitude images were evaluated from the hard copies by two independent observers. A graft was defined as patent if it was seen as a bright small round area on at least two consecutive images throughout the cardiac cycle at a position consistent with the expected location for that graft. Results : MR images were obtained successfully for 23 patients (61%). The sagittal planes were most helpful in visualizing the cross-section of sapheneous vein bypass graft to left circumflex artery branch, whereas the transverse planes were used for identification of internal mammary artery grafts to left anterior descending coronary artery or its branch and identification of saphenous vein grafts to right coronary artery. Forty five grafts were visible using this MR technique, while the grafts were not visible on seven saphenous vein grafts and two internal mammary artery grafts. In two patients showing symptoms of myocardial ischemia, one or two bypass grafts were not visible. Imaging, perpendicular plane to a CABG was important to visualize the flow inside the CABG with maximum sensitivity. Conclusion : Evaluation of patency of the bypass graft was clinically feasible by 2D-FASTCARD MR imaging, whereas any invisible bypass grafts should be further studied by contrast-enhanced MR angiography or by conventional angiography for confirmation of abnormalities.