• 대한의용생체공학회:의공학회지
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• 제27권4호
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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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• 제30권sup1호
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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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• 제25권3호
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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.

• 대한방사선기술학회지:방사선기술과학
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• 제39권1호
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• pp.59-69
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• 2016

Computed tomographic angiography (CTA)의 (조영제 집적 정점시간에 영향을 미치는 특성 인자를 분석하여: analyzing factors influencing on the integrated bolus peak timing in contrast-enhanced) 개인별 정점 시간을 계량적(Systems analysis)으로 산정해 검사에 직접 적용함으로써 예비검사(monitoring scan)에 의한 불필요한 방사선 피폭을 예방하는데 목적이 있다. CTA의 예비검사(monitoring scan)을 통해 얻은 조영제 집적 정점시간과 개인별 측정치들 간의 상관관계분석을 통해 영향인자를 파악한 다음, 다중선형회귀분석에 의한 회귀식으로 적정시간을 산출하였다. 결과로는 CTA의 평균 방사선 노출량은 $716.53mGy{\cdot}cm$였고, 예비검사(monitoring scan) 15.52 mGy (2 ~ 34 mGy)로 나타났다. 장기별 변환요소(conversion factor)를 적용한 결과, 전체 선량은 평균 1.5 mSv였고, 예비검사 선량은 0.23 mSv로 나타났다. 특성인자의 측정치와 조영제 정점시간의 상관관계분석 결과, 남성은 심박동수에서, 여성은 심박동수와 최저혈압, 혈당에서 음의 상관관계를 보였으며, 통계적으로 매우 유의하였다(p<.01). 회귀분석결과, 남성은 심박동수가 한 단계 증가할 때마다 -0.160배로, 여성은 최저혈압과 심박동수, 혈당에 따라 각각 -0.004, -0.174, -0.006배로 유의하게 감소하였다. 실측한 조영제 정점시간과 회귀식에 의해 산출된 정점시간의 일치도 검사에서 남여 대상자 모두에서 일치도가 매우 높았다. 본 연구에서는 검사 전에 환자 개인별 조영제 집적 정점시간을 산정하여 적용하면 예비검사를 생략함으로써 불필요한 방사선피폭을 예방할 수 있을 것으로 사료된다.

• 지질공학
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• 제3권3호
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• pp.231-239
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• 1993

본 연구에서는 지층속도가 이방성의 일종인 횡적등방성을 갖는 지역에서의 시추공 간 탄성파 주시자료를 역산하여 속도 이상대를 규명하는 연구를 시행하였다. 등방성 및 횡적등방성이 모형지층에 대해 파선추적법으로 합성 탄성파 주시를 구한 후, 이 주시자료에 대해 이방성을 고려한 ART 역산법과 이방성을 고려하지 않은 일반적인 ART 연산법에 의해 속도 분포를 구해본 결과, 이방성을 고려한 ART법에 의하면 이방성 및 등방성 지층의 속도분포가 잘 결정되었으며 일반적 ART법에 의하면 등방성 지층의 속도는 잘 결정되나 이방성 지층의 속도에는 오차가 많이 발생하였다. 따라서 지층의 이방성 또는 횡적등방성에 대한 사전 정보가 없을 때에는 이방성을 고려한 ART법을 적용하는 것이 좋을 것이다.

• Imaging Science in Dentistry
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• 제34권2호
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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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1687-1692
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• 2004

CT 사진을 이용하여 살아있는 사람의 비강 형상을 얻고 RP 를 이용하여 모형을 만들고 이 모형 으로 정교한 비강 유로 모형을 제작하였고, 호흡을 정확하게 모사하는 펌프를 만들었다. 사람의 호흡 데이터를 이용하여 캠을 제작하고 대형 피스 톤 펌프를 만들어 사람의 호흡을 정확 하게 모사 하였다. 이를 이용하여 생리적 주기를 갖는 비강 내 유동에 대한 결과를 획득하고 기존의 일정유량 하의 실험결과와 비교 분석하였다.

• Imaging Science in Dentistry
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• 제46권4호
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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.

• 한국임상수의학회지
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• 제31권4호
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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.

• 한국임상수의학회지
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• 제35권2호
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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.