• Imaging Science in Dentistry
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• v.34 no.3
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• pp.129-136
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• 2004

Purpose: To evaluate whether cone beam computed tomography can depict the distribution, position, frequency, relative vertical dimension, and the diameter of the lingual foramen and direction of lingual bone canal. Materials and Methods : Cone beam computed tomography of mandible was performed on 25 males and 25 females with no history of any orthodontic treatments or any other dental surgeries. A statistical comparison was done on the mean values of males and females. Results: In the location and distribution of lingual foramina, median lingual foramen was found in all subjects and lateral lingual foramen in 58%. In the lateral lingual foramen, bilateral type was found in 28% and unilateral type in 30%. In the number of lingual foramina, median lingual foramen had two foramina and lateral lingual foramen had one foramen, mostly. In the relative mean vertical dimension of lingual foramina, median lingual foramen was 0.03±0.08, and both lateral lingual foramina was 0.20±0.04. The mean diameter of lingual foramina, median lingual foramen was 0.9mm±0.28, right lateral lingual foramen was 0.92mm±0.23, and left lateral lingual foramen was 0.88mm±0.27. The most frequent direction of the lingual bone canals, median lingual bone canal proceeded in anteroinferior direction and lateral lingual bone canal in anterosuperolateral direction. Conclusion : Cone beam computed tomography can be helpful for surgery and implantation on the mandibular area. Radiologist should be aware of this anatomical feature and its possible implications.

• Imaging Science in Dentistry
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• v.32 no.1
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• pp.27-33
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• 2002

Purpose: To evaluate the influence of threshold value of computed tomography on the accuracy of rapid prototyping (RP) medical model Material and Methods : CT datas of a human dry skull were transferred from CT scanner via compact disk to a personal computer (PC). 3-dimensional image reconstruction on PC by V-works/sup TM/ 3.0 (CyberMed. Inc.) software and RP models fabrication were followed. 2-RP models were produced by threshold value of 500 and 800 selected in surface rendering process. Linear measurements between arbitrary 12 anatomical landmarks on dry skull, 3-D image model, and 2-RP models were done and compared. Thus, the accuracy of 500 RP and 800RP models was respectively evaluated. Results: There was mean difference (% difference) in absolute value of 2.27 mm (2.73%) between linear measurements of dry skull and 500 RP model. There was mean difference (% difference) in absolute value of 1.94 mm (2.52%) between linear measurements of dry skull and 800 RP model. Conclusion: Slight difference of threshold value in rendering process of 3-D modelling made a influence on the accuracy of RP medical model.

• Imaging Science in Dentistry
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• v.47 no.4
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• pp.275-279
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• 2017

Soft tissue calcification is a pathological condition in which calcium and phosphate salts are deposited in the soft tissue organic matrix. This study presents an unusual calcification noted in the cartilaginous portion of the Eustachian tube. A 67-year-old woman presented for dental treatment, specifically for implant placement, and cone-beam computed tomography (CBCT) was performed. The CBCT scan was reviewed by a board-certified oral and maxillofacial radiologist and revealed incidental findings of 2 distinct calcifications in the cartilaginous portion of the Eustachian tube. To the authors' knowledge, no previous study has reported the diagnosis of Eustachian tube calcification using CBCT. This report describes an uncommon variant of Eustachian tube calcification, which has a significant didactic value because such cases are seldom illustrated either in textbooks or in the literature. This case once again underscores the importance of having CBCT scans evaluated by a board-certified oral and maxillofacial radiologist.

• Imaging Science in Dentistry
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• v.32 no.2
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• pp.119-122
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• 2002

Two cases of Eagle's syndrome are reported. The first case involved a 31-year-old man who complained of pain in his throat and pain at preauricular area on turning his head. Panoramic and computed tomography (CT) views showed bilateral stylohyoid ligament ossification. The symptoms were relieved after surgical removal. The second case involved a 56-year-old female whose chief complaints were a continuous dull pain and occasional 'shooting' pain on lower left molar area. During the physical examination, an ossified stylohyoid ligament was palpated at the left submandibular area. Panoramic and CT images showed prominent bilateral stylohyoid ligament ossification. CT scans also showed hypertrophy of left medial and lateral pterygoid muscles. The symptoms were relieved after medication. CT is a useful tool for the examination of ossified stylohyoid ligaments and studying the relationship between Eagle's syndrome and adjacent soft tissue.

• Imaging Science in Dentistry
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• v.54 no.2
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• pp.201-206
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• 2024

This report showed a case of temporomandibular joint (TMJ) ankylosis suspected to be associated with ankylosing spondylitis based on the observation of bony ankylosis of the cervical spine on computed tomography (CT) images. A 53-year-old man presented with a chief complaint of difficulty in opening his mouth. His medical history indicated that in his 20 s, he became aware of the difficulty in moving his neck. CT revealed marked osteoarthritic changes in the right mandibular condyle, suggesting fibrotic TMJ ankylosis. In addition, bony ankylosis of the cervical vertebral body and facet joints from the axis (C2) to C5 in continuity was observed. CT of the entire spine also showed bony deformity of the sacroiliac joints and bony ankylosis. Based on these findings, ankylosing spondylitis was suspected. The possibility of an ankylosing spondylitis complication should be considered in cases of TMJ ankylosis if bony ankylosis of the cervical spine is observed.

• Imaging Science in Dentistry
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• v.33 no.3
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• pp.137-141
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• 2003

Purpose: To evaluate the precision of measurements taken of dental implants in bucco-lingually sectioned views of the maxilla by linear tomograms of the panorama and to assess the visibility of the inferior wall of the maxillary sinus. Materials and Methods : Eighty sites prepared with implants of gutta percha cone in the sockets of the upper premolars and molars of 10 dry skulls were radiographically examined using linear tomograms of panorama, and scanned coronally and axially by computed tomography. The differences in mm between the measurements in bucco-lingually sectioned images of maxillary alveolar bone and the true length and width of the implanted gutta percha cones were compared as mean values (mean) and standard deviations (SD) for each radiographic technique. Linear tomography of panorama was compared with computed tomography for visualization of the relationship between the inferior wall of maxillary sinus and the end of each implant. Results: The deviations between the actual implant length and the measured values taken from the linear tomograms (0.44±0.39 mm) was significantly less than the measured values from the multiplanar reconstructed images of the axially scanned computed tomogram (1.21 ± 0.90 mm). There was statistically significant difference (p < 0.05) between two techniques in the differences between the measurements and true implant length. The relationship of the inferior border of maxillary sinus with end of implant was worse identified with the linear tomogram of panorama (68%) than the multiplanar reconstructed image of axially scanned computed tomogram (99%). Conclusion: We could not find any differences in the accuracy of length measurement between the linear tomogram of panorama and computed tomogram, but computed tomogram allowed for a better visualization of the inferior wall of the maxillary sinus than the linear tomogram.

• Imaging Science in Dentistry
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• v.52 no.2
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• pp.133-140
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• 2022

Purpose: The aim of this review was to systematically analyze the available literature on the correlation between the gray values (GVs) of cone-beam computed tomography (CBCT) and the Hounsfield units (HUs) of computed tomography (CT) for assessing bone mineral density. Materials and Methods: A literature search was carried out in PubMed, Cochrane Library, Google Scholar, Scopus, and LILACS for studies published through September 2021. In vitro, in vivo, and animal studies that analyzed the correlations GVs of CBCT and HUs of CT were included in this review. The review was prepared according to the PRISMA checklist for systematic reviews, and the risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool. A quantitative analysis was performed using a fixed-effects model. Results: The literature search identified a total of 5,955 studies, of which 14 studies were included for the qualitative analysis and 2 studies for the quantitative analysis. A positive correlation was observed between the GVs of CBCT and HUs of CT. Out of the 14 studies, 100% had low risks of bias for the domains of patient selection, index test, and reference standards, while 95% of studies had a low risk of bias for the domain of flow and timing. The fixed-effects meta-analysis performed for Pearson correlation coefficients between CBCT and CT showed a moderate positive correlation (r=0.669; 95% CI, 0.388 to 0.836; P<0.05). Conclusion: The available evidence showed a positive correlation between the GVs of CBCT and HUs of CT.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7C
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• pp.601-609
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• 2012

In this paper, a limited-view CT image reconstruction method was studied to reduce the scan times and the X-ray dose for the patients. To reduce streak artifacts which is caused by insufficient number of views, we introduce a sinogram interpolation method based on image matching. Image matching is achieved using the characteristics of the neighboring views including intensity, gradient and distance between the pixels. Interpolation is performed using the image matching results.. A numerical phantom and Al-acryl phantom were used for evaluating the effectiveness of the proposed interpolation method. The results showed that streak artifacts were reduced in the reconstructed images while the details of the images were preserved. Moreover, maximum 5% improvements in terms of PSNR were observed.

• Tunnel and Underground Space
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• v.29 no.3
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• pp.184-196
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• 2019

This study aims to extract a 3D image of micro-cracks generated by hydraulic fracturing tests, using the deep learning method and X-ray computed tomography images. The pixel-level cracks are difficult to be detected via conventional image processing methods, such as global thresholding, canny edge detection, and the region growing method. Thus, the convolutional neural network-based encoder-decoder network is adapted to extract and analyze the micro-crack quantitatively. The number of training data can be acquired by dividing, rotating, and flipping images and the optimum combination for the image augmentation method is verified. Application of the optimal image augmentation method shows enhanced performance for not only the validation dataset but also the test dataset. In addition, the influence of the original number of training data to the performance of the deep learning-based neural network is confirmed, and it leads to succeed the pixel-level crack detection.

• Journal of Korean Neurosurgical Society
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• v.51 no.5
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• pp.316-319
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• 2012

A 24-year-old man presented with mental change, fever, abdominal pain, tenderness and palpable mass on the lower abdomen. He was a non-Korean engineer and did not accompany a legal guardian, so medical history taking was difficult due to his mental status. Brain magnetic resonance imaging showed multiple rim-enhanced lesions of the brain, and abdominal computed tomography showed huge paraspinal abscess. Chest X-ray and computed tomography showed poorly defined nodular opacities. We initially thought that this patient was infected with toxoplasmosis with typical cerebral image finding and immunoglobulin laboratory finding of cerebrospinal fluid and serum study. The abdominal abscess was confirmed as tuberculosis through the pathologic finding of caseous necrosis. We used anti-tuberculosis medication and anti-toxoplasmosis medication for almost 4 months, and then his clinical state and radiological findings were considerably improved.