• Journal of Biomedical Engineering Research
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• v.27 no.4
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• pp.189-196
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• 2006

Micro computed tomography (micro-CT) has been used for in vivo animal study owing to its noninvasive and high spatial resolution capability. However, the sizes of existing detectors for micro-CT systems are too small to obtain whole-body images of a small animal object with $\sim$10 micron resolution and a part of its bones or other organs should be extracted. So, we have introduced the zoom-in micro-tomography technique which can obtain high-resolution images of a local region of an live animal object without extracting samples. In order to verify our zoom-in technique, we performed in vivo animal bone study. We prepared some SD (Sprague-Dawley) rats for making osteoporosis models. They were divided into control and ovariectomized groups. Again, the ovariectomized group is divided into two groups fed with normal food and with calcium-free food. And we took 3D tomographic images of their femurs with 20 micron resolution using our zoom-in tomography technique and observed the bone changes for 12 weeks. We selected ROI (region of interest) of a femur image and applied 2D FDT (fuzzy distance transform) to measure the trabecular bone thickness. The measured results showed obvious bone changes and big differences between control and ovariectomized groups. However, we found that the reliability of the measurement depended on the selection of ROI in a bone image for thickness calculation. So, we extended the method to 3D FDT technique. We selected 3D VOI (volume of interest) in the obtained 3D tomographic images and applied 3D FDT algorithm. The results showed that the 3D technique could give more accurate and reliable measurement.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup1
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• pp.68-72
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• 2001

Objective : The goal of this study was to document the influence of the treatment modality(surgery versus endovascular treatment) on the development of chronic shunt-dependent hydrocephalus in a series of 296 patients treated after aneurysmal subarachnoid hemorrhage(SAH). Methods : The following parameters were retrospectively analyzed for association with chronic shunt-dependent hydrocephalus : 1) Age and Sex, 2) Hunt and Hess grade, 3) Fisher computed tomographic grade, 4) aneurysm location, and 5) treatment modality(surgery versus endovascular treatment). Results : Thirty-six of 251 patients(14.3%) who survived the SAH and its neurological and/or medical sequelae underwent definitive shunting for treatment of chronic hydrocephalus. The rate of shunt dependency was positively correlated with a higher age, a higher Hunt and Hess grade, a higher Fisher computed tomographic grade, and aneurysms arising at the anterior communicating artery(p<0.05). Conclusion : The results of the present study indicate that the treatment modality used does not affect the risk of the later development of chronic shunt-dependent hydrocephalus(surgery, 16.2% [25 of 154] ; endovascular treatment, 11.3% [11 of 97] ; p=0.45).

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.25 no.3
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• pp.240-250
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• 2022

Purpose: This study aimed to examine the advantages and usefulness of transient elastography (Fibroscan^®) in diagnosing non-alcoholic steatohepatitis in children and adolescents compared to those of abdominal computed tomography and liver ultrasonography. Methods: Forty-six children and adolescent participants aged between 6 and 16 years who underwent transient elastography (Fibroscan^®) as well as liver ultrasonography or abdominal computed tomography were included. Thirty-nine participants underwent liver ultrasonography and 11 underwent computed tomography. The physical measurements, blood test results, presence of metabolic syndrome, and the degree of liver steatosis and liver fibrosis were analyzed, and their correlations with transient elastography (Fibroscan^®), abdominal computed tomography, and liver ultrasonography, as well as the correlations between examinations, were analyzed. Results: Thirty-six participants (78.3%) were boys, and the mean age was 12.29±2.57 years, with a mean body mass index of 27.88±4.28. In the 46 participants, the mean values for aspartate aminotransferase, alanine aminotransferase, and total bilirubin were 89.87±118.69 IU/L, 138.54±141.79 IU/L, and 0.77±0.61 mg/dL, respectively. Although transient elastography (Fibroscan^®) and abdominal computed tomography grading had a statistically significant positive correlation with aspartate aminotransferase and alanine aminotransferase values, the correlations between the results of grading performed by transient elastography (Fibroscan^®), abdominal computed tomography, and liver ultrasonography were not statistically. Conclusion: We confirmed that each examination was correlated with the results of some blood tests, suggesting the usefulness and possibility of diagnosis and treatment of steatohepatitis mediated by transient elastography (Fibroscan^®) in the department of pediatrics.

• Journal of radiological science and technology
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• v.39 no.1
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• pp.59-69
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• 2016

The objective of this study was to analyze the factors influencing integrated bolus peak timing in contrast-enhanced computed tomographic angiography (CTA) and to determine a method of calculating personal peak time. The optimal time was calculated by performing multiple linear regression analysis, after finding the influence factors through correlation analysis between integrated peak time of contrast medium and personal measured value by monitoring CTA scans. The radiation exposure dose in CTA was $716.53mGy{\cdot}cm$ and the radiation exposure dose in monitoring scan was 15.52 mGy (2 - 34 mGy). The results were statistically significant (p < .01). Regression analysis revealed, a -0.160 times decrease with a one-step increase in heart rate in male, and -0.004, -0.174, and 0.006 times decrease with one-step in DBP, heart rate, and blood sugar, respectively, in female. In a consistency test of peak time by calculating measured peak time and peak time by using the regression equation, the consistency was determined to be very high for male and female. This study could prevent unnecessary dose exposure by encouraging in clinic calculation of personal integrated peak time of contrast medium prior to examination.

• The Journal of Engineering Geology
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• v.3 no.3
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• pp.231-239
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• 1993

This paper presents a result on the determination of velocity distribution by a tomographic inversion of crosshole seismic traveltimes in transversely isotropic(aniso tropic) media. The crosshole traveltimes used in this study are synthetic ones computed by ray tracing for some models having isotropic and transversely isotropic velocity distributions. The traveltimes are inverted by a general ART and ansotropic ART which considers the transversely isotropic effect during inver sion. The aniotropic ART gives accurate velodty distributions of transversely isotropic and isotropic models, while the isotropic ART determines accurate velocities only for the isotropic model but inaccurate for the transversely isotropic one. Therefore, the anisotropic ART may be used in case where no information is known on the isotropy or transverse isotropy of a survey area.

• Imaging Science in Dentistry
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• v.34 no.2
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• pp.91-97
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• 2004

Purpose : This study was performed to evaluate the diagnostic value of both planar and SPECT imagings by comparing the results with the clinical and other imaging modalities findings. Materials and Methods: A total of 578 joints with TMJ complaints were examined using planar scintigraphy and SPECT. The planar scintigraphy and SPECT findings were analyzed and compared to the clinical findings of pain, clicking, crepitus and limitation of mouth opening. Moreover we compared the accuracy of the planar scintigraphy and SPECT methods with the one of the panoramic, transcranial, tomographic and MR imaging methods. Results: The planar scintigraphy and SPECT methods showed a high sensitivity of 0.76-0.84 and low specificity of 0.25-0.45 toward the clinical findings: pain, clicking, crepitus and mouth opening restriction. Simple radionuclide uptake ratio was high in each group of patients with pain, crepitus, limitation of mouth opening (p < 0.05) complaints, in each group with positive bone changes on panoramic, transcranial or tomographic images, and in disc displaced group. Conclusion: Although both planar and SPECT imagings have limited specificity, these techniques are sensitive for detection of internal derangement of the TMJ.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1687-1692
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• 2004

Airflow in the nasal cavity of a normal Korean adult is investigated experimentally by tomographic PIV measurement. Knowledge of airflow characteristics in nasal cavities is essential to understand the physiology and pathology aspects of nasal breathing. Several studies have utilized physical models of the healthy nasal cavity to investigate the relationship between nasal anatomy and airflow. All of these researches on nasal airflow are under the condition of constant flow-rate. In this study, nasal cavity flow with the physiological period is investigated by tomographic PIV, for the first time. A pumping system that can produce the periodic flow is created. Thanks to a new method for the model casting by a combination of the rapid prototyping and curing of clear silicone, a transparent rectangular box containing the complex nasal cavity can be made for PIV. The CBC PIV algorithm is used for analysis. Phase-averaged mean and RMS velocity distributions are obtained for inspirational and expiration nasal airflows. The comparison with the constant flow case is appreciated. There exist many flow patterns depending on each phase.

• Imaging Science in Dentistry
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• v.46 no.4
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• pp.245-249
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• 2016

Purpose: This study was designed to evaluate differences in the required visibility of anatomic structures according to the diagnostic tasks of implant planning and periapical diagnosis. Materials and Methods: Images of a real skull phantom were acquired under 24 combinations of different exposure conditions in a cone-beam computed tomography scanner (60, 70, 80, 90, 100, and 110 kV and 4, 6, 8, and 10 mA). Five radiologists evaluated the visibility of anatomic structures and the image quality for diagnostic tasks using a 6-point scale. results: The visibility of the periodontal ligament space showed the closest association with the ability to use an image for periapical diagnosis in both jaws. The visibility of the sinus floor and canal wall showed the closest association with the ability to use an image for implant planning. Variations in tube voltage were associated with significant differences in image quality for all diagnostic tasks. However, tube current did not show significant associations with the ability to use an image for implant planning. conclusion: The required visibility of anatomic structures varied depending on the diagnostic task. Tube voltage was a more important exposure parameter for image quality than tube current. Different settings should be used for optimization and image quality evaluation depending on the diagnostic task.

• Journal of Veterinary Clinics
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• v.31 no.4
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• pp.329-332
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• 2014

A dog (Chihuahua, 2-year-old, intact female) was referred to us because of cluster seizure. She had history of falling from height few days before presentation. Brain computed tomography (CT) results demonstrated fracture line on right temporal bone and hypodense, edematous changes of the adjacent brain parenchyma on right cerebral parenchyma. Based on history, clinical signs, and diagnostic imaging findings, this patient was diagnosed to traumatic brain injury. After diagnosis, the patient was well controlled with anti-inflammatory drug and anti-epileptic drugs. When 30, 480, and 1260 days after initial brain CT examination, we performed serial brain CT rechecks. This case report describes serial clinical and brain CT findings after traumatic brain injury.

• Journal of Veterinary Clinics
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• v.35 no.2
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• pp.53-56
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• 2018

Computed tomography (CT) findings of hepatic adenoma in veterinary medicine are variable and unlike in human medicine, not defined clearly. A 12-year-old neutered male Shih Tzu presented after a seizure, with weight loss, salivation, and cachexia. An abdominal mass was identified on radiography, and ultrasonographic images showed a mixed echo pattern with marked vascularity. CT showed that the mass originated from caudate lobe, was heterogeneously hypoattenuated compared with the hepatic parenchyma, and had irregular margins. Contrast enhanced CT showed that the mass enhanced like the surrounding liver parenchyma. However, it contained unenhanced areas and enhanced vessels were observed in the arterial phase at the periphery of the mass. The margins of mass were more enhanced in the venous phase than the arterial phase and the hypoattenuating regions within the mass were not enhanced. Greater enhancing in the venous phase is seen with adenomas; however, the heterogeneous enhancement pattern, especially the marginal vascular enhancement and internal hypoattenuating regions, is seen with malignancy. Although this is a single case of hepatic adenoma, the atypical enhanced pattern of this case can provide useful information to predict the malignancy of primary liver tumor.