• Journal of Korean Neurosurgical Society
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• 제46권6호
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• pp.522-527
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• 2009

Objective : Atlantal arch defects are rare. Few cadaveric and imaging studies have been reported on the variations of such anomalies. Our goal in this study was to examine the incidence and review the clinical implications of this anomaly. Methods : A retrospective review of 1,153 neck or cervical spine computed tomography (CT) scans was performed to identify patients with atlantal arch defects. Neck CT scans were performed in 650 patients and cervical spine CT scans were performed in 503 patients. Posterior arch defects of the atlas were grouped in accordance with the classification of Currarino et al. In patients exhibiting this anomaly, special attention was given to defining associated anomalies and neurological findings. Results : Atlantal arch defects were found in 11 (11/1153, 0.95%) of the 1,153 patients. The type A posterior arch defect was found in nine patients and the type B posterior arch defect was found in two patients. No type C, D, or E defects were observed. One patient with a type A posterior arch defect had an anterior atlantal-arch midline cleft (1/1153, 0.087%). Associated cervical spine anomalies observed included one $C_{6-7}$ fusion and two atlantal assimilations. None of the reviewed patients had neurological deficits because of atlantal arch anomalies. Conclusion : Most congenital anomalies of the atlantal arch are found incidentally during investigation of neck mass, neck pain, radiculopathy, and after trauma.

• Tuberculosis and Respiratory Diseases
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• 제56권2호
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• pp.127-143
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• 2004

Computed tomography (CT) plays an important supplementary role in the evaluation of patients with heart disease. CT can be used to evaluate the aorta, pulmonary artery, pulmonary vein, cardiac chambers, coronary artery, valves and systemic veins (superior vena cava, inferior vena cava and hepatic veins). The "Learning Objectives" describe the normal anatomy and typical pathological conditions seen on axial scans and reformatted images from CT in patients with heart disease, focusing focus on frequent, fatal, and rare but characteristic diseases encountered in routine practice.

• The Journal of Korean Medicine
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• 제18권2호
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• pp.33-42
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• 1997

The authors studied the natural evaluation of lumbar soft disc herniation in 20 patients with lumbar radiculopathy that was successfully treated with conservative theraphy only. The first computed tomography (CT) examination was performed during the acute phase of the radiculopathy, and the second performed from 3 to 24 months after healing. The initial CT allowed classification of the herniations according to size: ten were considered small. ten medium. Comparison with follow-up scans showed that 18 of Herniations decreased between 0 and 25%, two decreased between 75 and 100%.

• Journal of Korean Neurosurgical Society
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• 제59권5호
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• pp.466-470
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• 2016

Objective : To determine imaging features that may separate adamantinomatous and papillary variants of craniopharyngiomas given that tumors with adamantinomatous signature features are associated with higher recurrence rates, morbidity, and mortality. We specifically reviewed calcification on CT, T1 bright signal intensity, and cystic change on T2 weighted images for differentiating these two types. Methods : We retrospectively reviewed the MRI and CT studies in 38 consecutive patients with pathologically proven craniopharyngiomas between January 2004 and February 2014 for the presence of calcification on CT scans, bright signal intensity on T1 weighted images, and cystic change on T2 weighted images. Results : Of the 38 craniopharyngiomas, 30 were adamantinomatous type and 8 were papillary type. On CT scans, calcification was present in 25 of 38 tumors. All calcified tumors were adamantinomatous type. Twenty four of 38 tumors had bright signal intensity on T1 weighted images. Of these 24 tumors, 22 (91.7%) were adamantinomatous and 2 were papillary type. Cystic change on T2 weighted images was noted in 37 of 38 tumors; only 1 tumor with papillary type did not show cystic change. Conclusion : T1 bright signal intensity and calcification on CT scans uniformly favor the adamantinomatous type over papillary type of craniopharyngioma in children. However, these findings are more variable in adults where calcification and T1 bright signal intensity occur in 70.6% and 58.8% respectively of adult adamantinomatous types of craniopharyngiomas.

• Archives of Craniofacial Surgery
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• 제22권4호
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• pp.193-198
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• 2021

Background: Nasal bone fractures are frequently encountered in clinical practice. Although fracture reduction is simple and correction requires a short operative time, low patient satisfaction and relatively high complication rates remain issues for many surgeons. These challenges may result from inaccuracies in fracture recognition and assessment or inappropriate surgical planning. Findings from immediate postoperative computed tomography (CT) scans and those performed at 4 to 6 weeks postoperatively were compared to evaluate the accuracy and outcomes of nasal fracture reduction. Methods: This retrospective study included patients diagnosed with nasal bone fractures at our department who underwent closed reduction surgery. Patients who did not undergo additional CT scans were excluded from the study. Clinical examinations, patient records, and radiographic images were evaluated in 20 patients with nasal bone fractures. Results: CT findings from immediately after surgery and a 1month follow-up were compared in 20 patients. Satisfactory nasal projection and aesthetically acceptable results were observed in patients with accurate correction or mild overcorrection, while undercorrection was associated with unfavorable results. Conclusion: Closed reduction surgery for correcting nasal bone fractures usually provides acceptable outcomes with relatively few complications. If available, immediate postoperative CT scans are recommended to guide surgeons in the choice of whether to perform secondary adjustments if the initial results are unsatisfactory. Based on photogrammetric data, nasal bone reduction with accurate correction or mild overcorrection achieved acceptable and stable outcomes at 1 month postoperatively. Therefore, when upward dislocation is observed on postoperative CT, one can simply observe without a subsequent intervention.

• Journal of Chest Surgery
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• 제26권3호
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• pp.209-213
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• 1993

The pathogenesis of the primary spontaneous pneumothorax is the rupture of subpleural bleb or bullae and subsequent sudden collapse of the affected lung. Mostly, the bullae or blebs are present bilaterally, but detecting the number, size, and location of the causating foci by plain chest film is quite difficult . We have performed chest CT scans for detecting the bullous lesions in 33 cases of primary spontaneous pneumothorax, and compared the results with surgical findings.1. Seventy-four blebs were identified in the chest CT scan, and 100 blebs or bullae were detected surgically [ Sensitivity was 0.74 ].2. Diagnosis rate was 80% [40/50] at right upper lobe, 75.7% [28/37] at left upper lobe, 55.6% at right lower lobe, and 25.0% at left lower lobe, respectively.3. Blebs or bullae smaller than 1 cm of its diameter were detected by 57.1% [24/42] of sensitivity, and in the cases of size larger than 1 cm, it revealed 86.2% [50/58] of sensitivity respectively.4. Of the 45 cases, 7 cases were false negative [15.6%], most of these were ruptured or small size [< 0.5 cm]. 5. One case was false positive, which was irregular adhesion at the apex of the lung.6. We could detect blebs or bullae with preoperative CT scans in 84.4% [38/45] of total patients. In conclusion, chest CT scan is a very advantageous diagnostic tool for proper management and preventing recurrence of primary spontaneous pneumothorax patient.

• Imaging Science in Dentistry
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• 제36권3호
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• pp.151-155
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• 2006

Purpose : Stroke is one of the leading causes of death in Korea. Atherosclerotic disease in the carotid artery bifurcation is the most common cause of stroke. The carotid artery calcification is easily appreciated by CT (Computed tomography). CT is often taken in a dental hospital for the diagnosis of inflammation, injury, cyst or tumor on maxillofacial region. However, there was no report of carotid artery calcification on CT in dental patients. This study was to determine the prevalence of carotid artery calcification on CT in dental patients. Materials and Methods : The presence of carotid artery calcification was evaluated by an experienced radiologist on CT scans of 287 patients (166 males, 121 females, average age 42, range 6 to 86 years) and the medical history of the patient and the interpretation of CT were reviewed. Results : Carotid artery calcification was detected on CT scans of 57 patients (19.8%; 35 males, 22 females). All the male patients with carotid artery calcification were older than 50, and all the female patients with carotid artery calcification were older than 60. Among the 57 patients, 10 had Diabetes mellitus, 20 had cardiovascular disease, 3 had history of stroke and 3 underwent radiation therapy for head and neck cancer. Carotid artery calcification was not included in the interpretation of CT of dental patients except one patient. Conclusion : The prevalence of carotid artery calcification on CT of dental patients was about 20% in this study. Carotid artery calcification should be included in the interpretation of CT of dental patients.

• Journal of Biomedical Engineering Research
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• 제35권5호
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• pp.151-159
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• 2014

Computed tomography (CT) is one of the most widely used medical imaging modality. However, substantial x-ray dose exposed to the human subject during the CT scan is a great concern. Region-of-interest (ROI) CT is considered to be a possible solution for its potential to reduce the x-ray dose to the human subject. In most of ROI-CT scans, the ROI is set to a circular shape whose diameter is often considerably smaller than the full field-of-view (FOV). However, an arbitrarily shaped ROI is very desirable to reduce the x-ray dose more than the circularly shaped ROI can do. We propose a new method to make a non-circular convex-shaped ROI along with the image reconstruction method. To make a ROI with an arbitrary convex shape, dynamic collimations are necessary to minimize the x-ray dose at each angle of view. In addition to the dynamic collimation, we get the ROI projection data with slightly lower sampling rate in the view direction to further reduce the x-ray dose. We reconstruct images from the ROI projection data in the compressed sensing (CS) framework assisted by the exterior projection data acquired from the pilot scan to set the ROI. To validate the proposed method, we used the experimental micro-CT projection data after truncating them to simulate the dynamic collimation. The reconstructed ROI images showed little errors as compared to the images reconstructed from the full-FOV scan data as well as little artifacts inside the ROI. We expect the proposed method can significantly reduce the x-ray dose in CT scans if the dynamic collimation is realized in real CT machines.

• Imaging Science in Dentistry
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• 제32권2호
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• pp.89-97
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• 2002

Purpose: The objective of this study is to find the differentiating characteristics of ameloblastomas and odontogenic keratocysts of the jaw by analyzing computed tomography (CT) images of the lesions, clarify radiological characteristics associated with jaw lesions, and to make a diagnsis based on these findings. Materials and Methods : Test subjects were chosen among the patients who were diagnosed as having an odontogenic keratocyst or ameloblastoma at the Yonsei University Dental Hospital from January 1996 to December 2000 and had CT scans taken preoperatively. The subject pool was comprised of 51 cases of odontogenic keratocyst and 37 cases of ameloblastoma. The following measures were used for image analysis of the lesion: the anatomic location, CT pattern, mesiodistal width, buccolingual width, the ratios between mesiodistal width and buccolingual width, height, CT number, homogeneity of radiodensity, the appearance of a sclerotic rim, continuity of adjacent cortical bone, and displacement and resorption of adjacent teeth. Results: Comparing the CT patten, mesiodistal width, buccolingual width, height, CT number, homogeneity, appearance of sclerotic rim, continuity of adjacent cortical bone, there were statistically significant differences between ameloblastoma and odontogenic keratocyst test subjects (p<0.05). Comparing the ratios between mesiodistal width and buccolingual width, displacement and resorption of adjacent teeth, there were no statistically significant differences (p>0.05). Conclusion: We compared odontogenic keratocysts and ameloblastomas in CT scans. They occurred most frequently in the posterior to the ramus of the mandible. The findings of patterns of the CT images showed that size and border of lesions were more aggressive in ameloblastomas than in odontogenic keratocysts. The internal contents represented an increased attenuation area (IAA) in odontopenic keratocyst. Odontogenic keratocysts were shown to have higher CT numbers than ameloblastomas.

• Journal of Biomedical Engineering Research
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• 제44권5호
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• pp.303-314
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• 2023

This study aimed to assess the practical feasibility of advanced deformable image registration (DIR) algorithms in radiotherapy by employing two distinct datasets. The first dataset included 14 4D lung CT scans and 31 head and neck CT scans. In the 4D lung CT dataset, we employed the DIR algorithm to register organs at risk and tumors based on respiratory phases. The second dataset comprised pre-, mid-, and post-treatment CT images of the head and neck region, along with organ at risk and tumor delineations. These images underwent registration using the DIR algorithm, and Dice similarity coefficients (DSCs) were compared. In the 4D lung CT dataset, registration accuracy was evaluated for the spinal cord, lung, lung nodules, esophagus, and tumors. The average DSCs for the non-learning-based SyN and NiftyReg algorithms were 0.92±0.07 and 0.88±0.09, respectively. Deep learning methods, namely Voxelmorph, Cyclemorph, and Transmorph, achieved average DSCs of 0.90±0.07, 0.91±0.04, and 0.89±0.05, respectively. For the head and neck CT dataset, the average DSCs for SyN and NiftyReg were 0.82±0.04 and 0.79±0.05, respectively, while Voxelmorph, Cyclemorph, and Transmorph showed average DSCs of 0.80±0.08, 0.78±0.11, and 0.78±0.09, respectively. Additionally, the deep learning DIR algorithms demonstrated faster transformation times compared to other models, including commercial and conventional mathematical algorithms (Voxelmorph: 0.36 sec/images, Cyclemorph: 0.3 sec/images, Transmorph: 5.1 sec/images, SyN: 140 sec/images, NiftyReg: 40.2 sec/images). In conclusion, this study highlights the varying clinical applicability of deep learning-based DIR methods in different anatomical regions. While challenges were encountered in head and neck CT registrations, 4D lung CT registrations exhibited favorable results, indicating the potential for clinical implementation. Further research and development in DIR algorithms tailored to specific anatomical regions are warranted to improve the overall clinical utility of these methods.