• Journal of the Korean Society of Radiology
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• v.82 no.6
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• pp.1556-1564
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• 2021

Purpose This study aimed to apply MR elastography (MRE) to achieve in vivo evaluation of the elastic properties of thigh muscles and validate the feasibility of quantifying the elasticity of normal thigh muscles using MRE. Materials and Methods This prospective study included 10 volunteer subjects [mean age, 32.5 years, (range, 23-45 years)] who reported normal activities of daily living and underwent both T2-weighted axial images and MRE of thigh muscles on the same day. A sequence with a motion-encoding gradient was used in the MRE to map the propagating shear waves in the muscle. Elastic properties were quantified as the shear modulus of the following four thigh muscles at rest; the vastus medialis, vastus lateralis, adductor magnus, and biceps femoris. Results The mean shear modulus was 0.98 ± 0.32 kPa and 1.00 ± 0.33 kPa for the vastus medialis, 1.10 ± 0.46 kPa and 1.07 ± 0.43 kPa for the vastus lateralis, 0.91 ± 0.41 kPa and 0.93 ± 0.47 kPa for the adductor magnus, and 0.99 ± 0.37 kPa and 0.94 ± 0.32 kPa for the biceps femoris, with reader 1 and 2, respectively. No significant difference was observed in the shear modulus based on sex (p < 0.05). Aging consistently showed a statistically significant negative correlation (p < 0.05) with the shear modulus of the thigh muscles, except for the vastus medialis (p = 0.194 for reader 1 and p = 0.355 for reader 2). Conclusion MRE is a quantitative technique used to measure the elastic properties of individual muscles with excellent inter-observer agreement. Age was consistently significantly negatively correlated with the shear stiffness of muscles, except for the vastus medialis.

• Journal of the Korean Society of Radiology
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• v.81 no.6
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• pp.1412-1423
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• 2020

Purpose Some patients with neonatal seizures show diffuse, symmetric diffusion-restricted lesions in the cerebral white matter. The aim of this study was to describe clinical and imaging findings of patients with neonatal seizures who had diffuse, symmetric diffusion-restricted lesions without any structural or metabolic etiology. Materials and Methods A total of 56 neonates aged less than 1 week underwent brain magnetic resonance imaging (MRI) for evaluation of seizures from November 2008 to February 2017. After excluding 43 patients, 13 patients showed diffuse white matter abnormality on diffusion-weighted imaging. Initial and follow-up clinical and MRI findings were analyzed retrospectively. Results All 13 patients were born at full term. Among the ten patients who underwent a stool test for viruses, six were positive for rotavirus and one for astrovirus. MRI revealed diffuse, symmetric diffusion-restricted lesions distributed along the cerebral white matter, thalami, and midbrain variably. Conclusion Diffuse, symmetric diffusion-restricted lesions involving the cerebral white matter can be seen in patients with neonatal seizures without any structural or metabolic etiology. Rotavirus is commonly but not exclusively detected in these patients. Nevertheless, viral infection-associated encephalopathy should be considered for patients with characteristic clinical and MRI findings.

• Archives of Plastic Surgery
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• v.34 no.5
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• pp.663-666
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• 2007

Purpose: Autologous fat injection into the facial area is a frequently used technique in aesthetic plastic surgery for augmentation of the soft tissue. Fat injection is a very safe procedure because of the advantage of being autologous tissue. Minimal foreign body reaction or infections are noted after fat injection. However, there may be some complications including those as severe as blindness. There have been some case reports on visual disturbances after autologous fat injection reported in the literature. Methods: A 21-year-old female patient underwent autologous fat injection into left eyebrow area to correct depression of soft tissue. Immediately after injection of autologous fat, she complained sudden visual loss on the left eye. She had come to our emergency room and ophthalmologic evaluation showed that the patient could only recognize hand motion. There was no abnormality of the optic nerve on magnetic resonance imaging. Suspecting an ischemic optic neuritis from fat embolism of the central retinal artery, the patient was treated conservatively with occular massage, antiglaucomatic agent, anti-inflammatory drugs and antibiotics. Visual field examination showed visual defect of half the lower hemisphere. Results: While maintaining antiglaucomatic agents and non steroidal anti inflammatory drugs, fundoscopic examination showed no abnormalities on the second day of admission. Visual field examination showed an improvement on the fourth day along with decreased eyeball pain. Significant improvement of vision was noted and the patient was discharged on the fifth day of admission. The patient was followed-up 2 days afterwards with improved vision and visual field defect. Conclusion: We describe an unusual case of sudden unilateral visual disturbance following autologous fat injection into periorbital area.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.2
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• pp.105-118
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• 2008

Shotcrete is one of the main support materials in tunnelling. Its bonding state on excavated rock surfaces controls the safety of the tunnel: De-bonding of shotcrete from an excavated surface decreases the safety of the tunnel. Meanwhile, the bonding state of shotcrete is affected by blasting during excavation at tunnel face as well as bench cut. Generally, the bonding state of shotcrete can be classified as void, de-bonded, or fully bonded. In this study, the state of the back-surface of shotcrete is investigated using impact-echo (IE) techniques. Numerical simulation of IE technique is performed with ABAQUS. Signals obtained from the IE simulations were analyzed at time, frequency, and time-frequency domains, respectively. Using an integrated active signal processing technique coupled with a Short-Time Fourier Transform (STFT) analysis, the bonding state of the shotcrete can be evaluated accurately. As the bonding state worsens, the amplitude of the first peak past the maximum amplitude in the time domain waveform and the maximum energy of the autospectral density are increasing. The resonance frequency becomes detectable and calculable and the contour in time-frequency domain has a long tail parallel to the time axis. Signal characteristics with respect to ground condition were obtained in case of fully bonded condition. As the ground condition worsens, the length of a long tail parallel to the time axis is lengthened and the contour is located in low frequency range under 10 kHz.

• Journal of Chest Surgery
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• v.37 no.3
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• pp.286-291
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• 2004

Mediastinum is a very rare primary site of liposarcoma. In general, wide surgical excision with adequate resection margin is the treatment of choice for lipesarcoma. We experienced a case of liposarcoma in a 24 year-old male who complained of dyspnea and chest discomfort. Symptoms had been developed a month before admission, and the intensity had been gradually increased. He visited another general hospital, and there he received left closed thoracostomy because hemothorax was suspected. Afterwards, he was transferred to our hospital without a specific diagnosis, on review of outside chest computed tomography film, mass shadow was detected in the mediastinum. For the further evaluation, we checked the chest sonography and chest magnetic resonance imaging. MRI showed 10 cm sized mass contacted with pulmonary artery trunk and left main pulmonary artery. The radiologist strongly suggested sarcoma. On the 4th day after admission, we performed emergent exploratory left thoracotomy for hematoma evacuation because mediastinal shifting progressed and heart rate was increased. Biopsy confirmed that the evacuated materials were extraskeletal myxoid chondresarcoma, so we performed extrapleural left pneumonectomy including diaphragm and a part of the pericardium. The final pathologic diagnosis was myxoid/round cell liposarcoma. He was discharged without complication and systemic chemotherapy was scheduled to begin 2 month later. During chemotherapy, local recurrence and peritoneal metastasis developed, and he died 10 month after the surgical excision. We report this case with reviewal of literature.

• Journal of the Korean Society of Radiology
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• v.5 no.5
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• pp.289-294
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• 2011

The aim of this study is to evaluate the differences of ejection fraction of left ventricle through the quantitative analysis of diastolic and systolic volumes according to slices selected using cardiac MR imaging. A total of 12 volunteers (7 normal, 1 myocardium bridge, and 4 arrhythmia) underwent cardiac MRI on a MR scanner(Magnetom Trio, Siemens, Germany). Ejection fractions for quantitative analysis were calculated at single slice of center of left ventricle, 3, 5, and 6-7 slices extending from the center of left ventricle. Average values were analyzed for evaluating differences of ejection fraction according to the number of slices selected. Mean value of normal person of ejection fraction were 67.14% at single slice of center of left ventricle, 66.24% at 3 slices, 65.63% at 5 slices, and 65.29% at 6-7 slices. While ejection fraction obtained from a patient with 61.74% at single slice of center of left ventricle, 60.92% at 3 slices, 60.89% at 5 slices, and 61.89% at 6-7 slices. There was no significant differences by the number of slices selected. This study demonstrates that ejection fraction obtained from single slice of center of left ventricle may represent a optimum parameter for cardiac function, instead of the value calculated on the variable slices selected.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.11
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• pp.1217-1223
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• 2007

Advanced microwave absorbers for wide oblique incidence angles are required in many applications including wireless communication or vehicle identification in ITS(Intelligent Transport System) where 5.8 GHz DSRC(Dedicated Short Range Communication) system is applied. In this study, two-layered microwave absorber(with a laminate structure of dielectric/magnetic composites) has been designed for the achievement of low reflection coefficient over wide incidence angles at 5.8 GHz. Iron flake particles are used as the filler in the absorbing layer, and the magnetic composite sheet exhibits high magnetic loss due to ferromagnetic resonance in gigahertz frequencies. The surface layer of low dielectric constant containing small amount of carbon black is used as the impedance transformer. On the basis of transmission line theory, the reflection loss has been calculated for the two-layer structure with variation of incident angles for both TE(Transverse Electric) and TM(Transverse Magnetic) polarizations. At the optimum thickness of the composite layers, a low value of reflection loss(less than -10 dB) has been predicted for wide incidence angles up to $55^{\circ}$ which is in good agreement with the measured value determined by free-space measurement.

• Journal of Chest Surgery
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• v.30 no.5
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• pp.493-500
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• 1997

We performed this study to evaluate hepatic venous drainage in atrial isomerism by MR and the clinical significance of anomalous hepatic venous return in total cavopulmonary shunt operation. Numbers and locations of hepatic veins in twenty-two patients with isomerism(thirteen with right isomerism and nine with left isom rism) were evaluated by MR. Operative procedure of hepatic veins and postoperative arterial oxygen saturation were compared with hepatic vein connection in six patients after total cavopulmonary shunt operation. Among nine patients with left isomerism, hepatic venous return was totally anomalous via a single opening in eight, and via two separate openings in one. Among thirteen patients with right isomerism, partial anomalous hepatic venous connection directly to the atrium was seen in four. One showed total anomalous hepatic venous connection to atrium through one opening. Total cavopulmonary shunt operation was performed in 6 patients. Hepatic veins were connected to pulmonary arteries in four patients who had one atrial opening of hepatic vein andlor IVC, or two ipsilateral atrial opening of hepatic veins and IVC. In conclusion, hepatic vein drainage to atrium is variable in atrial isomerism. MR is useful for evaluation of hepatic vein drainage in atrial isomerism and surgical pla ning.

• Nutrition Research and Practice
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• v.8 no.5
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• pp.509-515
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• 2014

BACKGROUND/OBJECTIVES: The root of Vitis amurensis Ruprecht, a sort of wild-growing grape, has been used in oriental medicine for treatment of skin ailments; however, its dermatological activity is not sufficiently understood. The aim of this study was to investigate tyrosinase inhibitory and anti-melanogenic activities of V. amurensis Ruprecht root methanol extract (VARM) in B16F10 mouse melanoma cells and to attempt to isolate and identify the active compound issued from VARM. MATERIALS/METHODS: Anti-melanogenic activity of VARM was analyzed in ${\alpha}$-melanocyte stimulating hormone (MSH)-stimulated B16F10 cells through evaluation of antioxidative activity as well as inhibited tyrosinase activity and melanin contents compared with those of kojic acid and arbutin. After anti-melanogenic analysis of VARM, serial fractionation, nuclear magnetic resonance (NMR), and thin layer chromatorgraphy (TLC) were applied for identification of active compounds contained in VARM. RESULTS: VARM significantly inhibited oxidative stress and tyrosinase activity and attenuated ${\alpha}$-MSH-induced melanin production in B16F10 cells. For isolation of active compounds, VARM was fractionated using a series of organic solvents, including dichloromethane ($CH_2Cl_2$), ethyl acetate (EtOAc), and n-butanol (n-BuOH). Among fractions showing anti-melanogenic activity, the CH2Cl2 fraction induced the most potent attenuation of melanogenesis without cytotoxicity and the major compound in the $CH_2Cl_2$ fraction was identified as betulinic acid. Betulinic acid isolated from the $CH_2Cl_2$ fraction of VARM significantly attenuated ${\alpha}$-MSH-induced melanogenesis in a dose dependent manner, which was stronger than that of arbutin used as a positive control. CONCLUSIONS: These results indicate that VARM inhibits oxidative stress, tyrosinase activity, and ${\alpha}$-MSH-induced melanogenesis in B16F10 cells, due primarily to the active compound, betulinic acid, in the $CH_2Cl_2$ fraction.

• Progress in Medical Physics
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• v.28 no.4
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• pp.190-196
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• 2017

For the $ViewRay^{(R)}$ system (ViewRay Inc., Cleveland, OH, USA) which is representative of magnetic resonance (MR) guided radiotherapy machine, it is important to evaluate effectiveness of AAPM's TG-51 protocol and the effect of the magnetic field on absolute dosimetry. In order to measure the absolute dose, MR-compatible chamber and water phantom system manufactured in this study were used. The materials of the water phantom system were plastic of polymethyl methacrylate (PMMA) and non-ferrous materials. Due to the inherent feature of the $ViewRay^{(R)}$, all Co-60 sources are not located at gantry angle of $0^{\circ}$ while being located at gantry angle of $90^{\circ}$. For this reason, absolute dosimetry was performed based on the measurements in solid water phantom (SWP) and water which determine the SWP to water correction factor. For evaluation of output constancy with gantry angle, measurements were made with ionization chamber inserted in cylindrical water-equivalent phantom. For measured doses in water, the values of dose deviation according to a reference dose of 200 cGy for Head 1, Head 2 and Head 3 were -0.27%, -0.45% and -0.22%, respectively. For measured doses in SWP, the values of dose deviation according to a reference dose of 200 cGy for Head 1, Head 2 and Head 3 were -1.91%, -2.07% and -1.84%, respectively. All values of dose measured in SWP tended to be less than those measured in water by -1.63%. With the reference gantry angles of $0^{\circ}$ and $90^{\circ}$, the maximum values of deviation for Head 1, Head 2 and Head 3 were 0.48%, 1.06% and 0.40%, respectively. The measurement agreement is within the range of results obtainable for conventional treatment machines. The low strength of the magnetic field does not affect dose measurements. Using the SWP to water correction factor, absolute doses for $ViewRay^{(R)}$ system can be measured.