• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.279-282
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• 1997

Bayesian reconstruction methods for emission computed tomography have been a topic of interest in recent years, partly because they allow for the introduction of prior information into the reconstruction problem. Early formulations incorporated priors that imposed simple spatial smoothness constraints on the underlying object using Gibbs priors in the form of four-nearest or eight-nearest neighbors. While these types of priors, known as "membrane" priors, are useful as stabilizers in otherwise unstable ML-EM reconstructions, more sophisticated prior models are needed to model underlying source distributions more accurately. In this work, we investigate whether the "thin plate" model has advantages over the simple Gibbs smoothing priors mentioned above. To test and compare quantitative performance of the reconstruction algorithms, we use Monte Carlo noise trials and calculate bias and variance images of reconstruction estimates. The conclusion is that the thin plate prior outperforms the membrane prior in terms of bias and variance.

• Imaging Science in Dentistry
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• 제45권2호
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• pp.109-115
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• 2015

Central odontogenic fibroma (COF) is a rare benign tumor that accounts for 0.1% of all odontogenic tumors. A case of COF (simple type) of the mandible in a four-year-old boy is described in this report. The patient showed asymptomatic swelling in the right inferior border of the lower jaw for one week. A panoramic radiograph showed a poorly-defined destructive unilocular radiolucent area. Cone-beam computed tomography showed expansion and perforation of the adjacent cortical bone plates. A periosteal reaction with the Codman triangle pattern was clearly visible in the buccal cortex. Since the tumor had destroyed a considerable amount of bone, surgical resection was performed. No recurrence was noted.

• 한국임상수의학회지
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• 제37권6호
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• pp.367-370
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• 2020

Four dogs were incidentally diagnosed as plate-like atelectasis (PLA) by thoracic radiographs. The dogs underwent thoracic computed tomography (CT) examination with various causes. On the lateral radiographs, PLA lesions were observed as a single linear or curvilinear radiopaque area in all four dogs. Although PLA lesions were observed linear structures on dorsal and sagittal reformatted CT images as in the radiographs, it appeared pulmonary opacification or band shape on transverse images. Therefore, care should be taken to differentiate PLA from other pulmonary diseases.

• 대한치과교정학회지
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• 제52권1호
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• pp.75-79
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• 2022

Objective: To investigate remineralizing effect of three fluoride regimens on artificially demineralized enamel around orthodontic bracket by analyzing mineral density (MD) acquired from micro-computed tomography (micro-CT). Methods: Forty-eight bracket bonded bovine incisors were prepared to create demineralized enamel (DE) surface. The samples were divided into four groups according to the fluoride regimen: 1) no fluoridation, 2) 1.23% acidulated phosphate fluoride (APF) gel, 3) fluoridated toothpaste, and 4) 0.05% sodium fluoride mouthwash. Micro-CT was scanned after demineralization (T0), and 2 weeks (T1) and 4 weeks (T2) of fluoridation. Results: APF gel showed highest remineralization of DE during T1-T0 interval among the groups (p < 0.05); followed by toothpaste, mouthwash and no fluoridation. APF gel and toothpaste demonstrated significant increase in MD after 4 weeks of application (p < 0.05). Conclusions: Remineralization effects of three fluoride regimens were depicted through micro-CT analysis, of which APF gel was most effective.

• 대한수의학회지
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• 제61권4호
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• pp.31.1-31.4
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• 2021

A 15-year-old Schnauzer, showing right exophthalmos, was diagnosed as adenocarcinoma originated from the third eyelid gland. On computed tomography, a normal right third eyelid gland was not observed. Instead, a heterogeneous cystic mass invaded the retrobulbar space and displaced the eye globe dorsolaterally. In addition, lysis of the bony nasolacrimal duct was found, which was considered the tumor invasion. These findings indicated that third eyelid gland adenocarcinoma should be considered when a retrobulbar mass is found ventromedial to the globe without observation of the normal third eyelid and accompanies osteolysis of the bony nasolacrimal duct in dogs showing exophthalmos.

• 대한수의학회지
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• 제62권2호
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• pp.17.1-17.5
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• 2022

A 12-year-old castrated male Persian cat presented with abdominal distension and anorexia. The radiography revealed ascites, pleural effusion, and a cranioventral mediastinal mass. Ultrasonography showed a well-defined mass lesion within a thickened ileal segment with a transmural loss of layering and multiple hyperechoic nodules arising from the peritoneum. Computed tomography showed peritoneal thickening with contrast enhancement, a bulky heterogeneous ileal mass, and mesenteric involvement with diffuse nodules. An alimentary lymphoma was confirmed by fine needle aspiration of the small intestinal mass. This report describes the imaging features of lymphoma with peritoneal lymphomatosis in a cat.

• 대한치과교정학회지
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• 제47권5호
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• pp.277-288
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• 2017

Objective: Treating Class II subdivision malocclusion with asymmetry has been a challenge for orthodontists because of the complicated characteristics of asymmetry. This study aimed to explore the characteristics of dental and skeletal asymmetry in Class II subdivision malocclusion, and to assess the relationship between the condyle-glenoid fossa and first molar. Methods: Cone-beam computed tomographic images of 32 patients with Class II subdivision malocclusion were three-dimensionally reconstructed using the Mimics software. Forty-five anatomic landmarks on the reconstructed structures were selected and 27 linear and angular measurements were performed. Paired-samples t-tests were used to compare the average differences between the Class I and Class II sides; Pearson correlation coefficient (r) was used for analyzing the linear association. Results: The faciolingual crown angulation of the mandibular first molar (p < 0.05), sagittal position of the maxillary and mandibular first molars (p < 0.01), condylar head height (p < 0.01), condylar process height (p < 0.05), and angle of the posterior wall of the articular tubercle and coronal position of the glenoid fossa (p < 0.01) were significantly different between the two sides. The morphology and position of the condyle-glenoid fossa significantly correlated with the three-dimensional changes in the first molar. Conclusions: Asymmetry in the sagittal position of the maxillary and mandibular first molars between the two sides and significant lingual inclination of the mandibular first molar on the Class II side were the dental characteristics of Class II subdivision malocclusion. Condylar morphology and glenoid fossa position asymmetries were the major components of skeletal asymmetry and were well correlated with the three-dimensional position of the first molar.

• Imaging Science in Dentistry
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• 제49권4호
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• pp.257-263
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• 2019

Purpose: This study was performed to evaluate the dimensional accuracy of digital dental models constructed from cone-beam computed tomographic (CBCT) scans of polyvinyl siloxane (PVS) impressions and cast scan models. Materials and Methods: A pair of PVS impressions was obtained from 20 subjects and scanned using CBCT (resolution, 0.1 mm). A cast scan model was constructed by scanning the gypsum model using a model scanner. After reconstruction of the digital models, the mesio-distal width of each tooth, inter-canine width, and inter-molar width were measured, and the Bolton ratios were calculated and compared. The 2 models were superimposed and the difference between the models was measured using 3-dimensional analysis. Results: The range of mean error between the cast scan model and the CBCT scan model was -0.15 mm to 0.13 mm in the mesio-distal width of the teeth and 0.03 mm to 0.42 mm in the width analysis. The differences in the Bolton ratios between the cast scan models and CBCT scan models were 0.87 (anterior ratio) and 0.72 (overall ratio), with no significant difference (P>0.05). The mean maxillary and mandibular difference when the cast scan model and the CBCT scan model were superimposed was 53 ㎛. Conclusion: There was no statistically significant difference in most of the measurements. The maximum tooth size difference was 0.15mm, and the average difference in model overlap was 53 ㎛. Digital models produced by scanning impressions at a high resolution using CBCT can be used in clinical practice.

• 한국임상수의학회지
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• 제34권4호
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• pp.295-298
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• 2017

A 6-year-old female Pekingese dog, weighing 3.85 kg was presented with regurgitation, ptyalism, weight loss and anorexia. The dog was cachexic and severely dehydrated. Physical examination of the dog confirmed upper respiratory noise, which was classified as a stridor most apparent on inspiration, respiratory effort with stenotic nares. Upper respiratory signs were thought to be caused by brachycephalic syndrome. On the lateral thoracic radiograph, the caudal one third of the esophagus was visible as a soft tissue band. CT revealed oval-shaped, soft tissue attenuating mass in size of $2.3{\times}1.0{\times}1.1cm$ arising from caudal one third of the esophagus. The mass was protruding from esophageal wall to lumen and irregular margined with heterogenous contrast enhancement. The wall of cardia and fundus was focally thickened. Gastric lymph node was enlarged with contrast enhancing. On histopathologic examination, esophageal mass was confirmed as papillary adenocarcinoma, and the gastric sample showed the same result. In human, adenocarcinoma commonly occur in esophagus and cardia, but it has not been commonly reported in veterinary medicine. This report described computed tomographic features of adenocarcinoma of the esophagocardia region in a Pekingese dog with brachycephalic syndrome.

• Journal of Chest Surgery
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• 제43권2호
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• pp.204-207
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• 2010

68세 남자 환자가 흉통을 주소로 내원하여 시행한 심혈관 조영술에서 삼 혈관 질환이 발견되어 관상동맥 우회술을 계획하였다. 수술 전 검사로 시행한 컴퓨터 단층촬영 혈관 조영술에서 신동맥하 복부 대동맥부터 양측 총장골동맥에 걸친 거미줄 모양의 혈관 내 종괴가 발견되었다. 대동맥내 혈관 내막육종을 의심하고 심폐바이패스를 사용하지 않는 관상동맥 우회술과 함께 신동맥하 복부 대동맥과 양측 총장골동맥을 절제 후 치환하는 수술을 시행하였다. 병리검사 소견에서 대동맥 내 병변은 혈관 내막 육종이 의심되었다. 수술 후 3개월에 시행한 컴퓨터 단층촬영 혈관 조영술에서 잔존 또는 재발의 증거는 없었다.