1.Effect of variable scanning protocolson the pre-implant site evaluation of the mandiblein reformatted computed tomography.
Journal of Korean Academy of Oral and Maxillofacial Radiology 1999;29(1):21-32
PURPOSE: To evaluate the effect of variable scanning protocols of computed tomography for evaluation of pre-implant site of the mandible through the comparison of the reformatted cross-sectional images of helical CT scans obtained with various imaging parameters versus those of conventional CT scans. MATERIALS AND METHODS: A dry mandible was imaged using conventional nonoverlapped CT scans with 1 mm slice thickness and helical CT scans with 1 mm slice thickness and pitches of 1.0, 1.5, 2.0, 2.5 and 3.0. All helical images were reconstructed at reconstruction interval of 1 mm. DentaScan reformatted images were obtained to allow standardized visualization of cross-sectional images of the mandible. The reformatted images were reviewed and measured separately by 4 dental radiologists. The image qualities of continuity of cortical outline, trabecular bone structure and visibility of the mandibular canal were evaluated and the distance between anatomic structures were measured by 4 dental radiologists. RESULTS: On image qualities of continuity of cortical outline, trabecular bone structure and visibility of the mandibular canal and in horizontal measurement, there was no statistically significant difference among conventional and helical scans with pitches of 1.0, 1.5 and 2.0. In vertical measurement, there was no statistically significant difference among the conventional and all imaging parameters of helical CT scans with pitches of 1.0, 1.5, 2.0, 2.5 and 3.0. CONCLUSION: The images of helical CT scans with 1 mm slice thickness and pitches of 1.0, 1.5 and 2.0 are as good as those of conventional CT scans with 1 mm slice thickness for evaluation of pre-dental implant site of the mandible. Considering the radiation dose and patient comfort, helical CT scans with 1 mm slice thickness and pitch of 2.0 is recommended for evaluation of pre-implant site of the mandible.
Dental Implants
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Humans
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Mandible
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Tomography, Spiral Computed
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Tomography, X-Ray Computed
2.Clinical usefulness of facial soft tissues thickness measurement using 3D computed tomographic images.
Ho Gul JEONG ; Kee Deog KIM ; Seung Ho HAN ; Kyung Seok HU ; Jae Bum LEE ; Hyok PARK ; Seong Ho CHOI ; Chong Kwan KIM ; Chang Seo PARK
Korean Journal of Oral and Maxillofacial Radiology 2006;36(2):89-94
PURPOSE: To evaluate clinical usefulness of facial soft tissue thickness measurement using 3D computed tomographic images. MATERIALS AND METHODS: One cadaver that had sound facial soft tissues was chosen for the study. The cadaver was scanned with a Helical CT under following scanning protocols about slice thickness and table speed; 3 mm and 3 mm/sec, 5 mm and 5 mm/sec, 7 mm and 7 mm/sec. The acquired data were reconstructed 1.5, 2.5, 3.5 mm reconstruction interval respectively and the images were transferred to a personal computer. Using a program developed to measure facial soft tissue thickness in 3D image, the facial soft tissue thickness was measured. After the ten-time repeation of the measurement for ten times, repeated measure analysis of variance (ANOVA) was adopted to compare and analyze the measurements using the three scanning protocols. Comparison according to the areas was analyzed by Mann-Whitney test. RESULTS: There were no statistically significant intraobserver differences in the measurements of the facial soft tissue thickness using the three scanning protocols (p>0.05). There were no statistically significant differences between measurements in the 3 mm slice thickness and those in the 5 mm, 7 mm slice thickness (p>0.05). There were statistical differences in the 14 of the total 30 measured points in the 5 mm slice thickness and 22 in the 7mm slice thickness. CONCLUSION: The facial soft tissue thickness measurement using 3D images of 7 mm slice thickness is acceptable clinically, but those of 5 mm slice thickness is recommended for the more accurate measurement.
Cadaver
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Imaging, Three-Dimensional
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Microcomputers
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Tomography, Spiral Computed
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Tomography, X-Ray Computed
3.Congenital Bronchial Atresia.
Yo Won CHOI ; Ho Joo YOON ; Dong Ho SHIN ; Sung Soo PARK
Tuberculosis and Respiratory Diseases 2004;56(4):343-347
Congenital bronchial atresia is a rare anomaly, which results from a congenital focal obliteration of a proximal segmental or subsegmental bronchus, with normal development of the distal structures. The short atretic segment leads to the accumulation of mucus within the distal bronchi, forming a bronchocele and air trapping of the alveoli supplied by these bronchi. The diagnostic CT features include the presence of a branching opacity and the bronchocele, which radiate from the hilum and are surrounded by an area of hyperlucency.
Bronchi
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Bronchial Diseases
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Mucus
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Tomography, Spiral Computed
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Tomography, X-Ray Computed
4.Measurement of facial soft tissues thickness using 3D computed tomographic images.
Ho Gul JEONG ; Kee Deog KIM ; Seung Ho HAN ; Dong Won SHIN ; Kyung Seok HU ; Jae Bum LEE ; Hyok PARK ; Chang Seo PARK
Korean Journal of Oral and Maxillofacial Radiology 2006;36(1):49-54
PURPOSE: To evaluate accuracy and reliability of program to measure facial soft tissue thickness using 3D computed tomographic images by comparing with direct measurement. MATERIALS AND METHODS: One cadaver was scanned with a Helical CT with 3 mm slice thickness and 3 mm/sec table speed. The acquired data was reconstructed with 1.5 mm reconstruction interval and the images were transferred to a personal computer. The facial soft tissue thickness were measured using a program developed newly in 3D image. For direct measurement, the cadaver was cut with a bone cutter and then a ruler was placed above the cut side, The procedure was followed by taking pictures of the facial soft tissues with a high-resolution digital camera. Then the measurements were done in the photographic images and repeated for ten times. A repeated measure analysis of variance was adopted to compare and analyze the measurements resulting from the two different methods. Comparison according to the areas was analyzed by Mann-Whitney test. RESULTS: There were no statistically significant differences between the direct measurements and those using the 3D images (p>0.05). There were statistical differences in the measurements on 17 points but all the points except 2 points showed a mean difference of 0.5 mm or less. CONCLUSION: The developed software program to measure the facial soft tissue thickness using 3D images was so accurate that it allows to measure facial soft tissues thickness more easily in forensic science and anthropology.
Anthropology
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Cadaver
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Forensic Sciences
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Imaging, Three-Dimensional
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Microcomputers
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Tomography, Spiral Computed
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Tomography, X-Ray Computed
5.Three-dimensional image analysis of the skull using variable CT scanning protocols-effect of slice thickness on measurement in the three-dimensional CT images.
Ho Gul JEONG ; Kee Deog KIM ; Hyok PARK ; Dong Ook KIM ; Haijo JEONG ; Hee Joung KIM ; Sun Kook YOO ; Yong Oock KIM ; Chang Seo PARK
Korean Journal of Oral and Maxillofacial Radiology 2004;34(3):151-157
PURPOSE: To evaluate the quantitative accuracy of three-dimensional (3D) images by means of comparing distance measurements on the 3D images with direct measurements of dry human skull according to slice thickness and scanning modes. MATERIALS AND METHODS: An observer directly measured the distance of 21 line items between 12 orthodontic landmarks on the skull surface using a digital vernier caliper and each was repeated five times. The dry human skull was scanned with a Helical CT with various slice thickness (3, 5, 7 mm) and acquisition modes (Conventional and Helical). The same observer measured corresponding distance of the same items on reconstructed 3D images with the internal program of V-works 4.0 TM (Cybermed Inc., Seoul, Korea). The quantitative accuracy of distance measurements were statistically evaluated with Wilcoxons' two-sample test. RESULTS: 11 line items in Conventional 3 mm, 8 in Helical 3 mm, 11 in Conventional 5 mm, 10 in Helical 5 mm, 5 in Conventional 7 mm and 9 in Helical 7 mm showed no statistically significant difference. Average difference between direct measurements and measurements on 3D CT images was within 2 mm in 19 line items of Conventional 3 mm, 20 of Helical 3 mm, 15 of Conventional 5 mm, 18 of Helical 5 mm, 11 of Conventional 7 mm and 16 of Helical 7 mm. CONCLUSION: Considering image quality and patient's exposure time, scanning protocol of Helical 5 mm is recommended for 3D image analysis of the skull in CT.
Cephalometry
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Humans
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Imaging, Three-Dimensional*
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Seoul
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Skull*
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Tomography, Spiral Computed
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Tomography, X-Ray Computed*
6.Reduction of Metal Artifact around Titanium Alloy-based Pedicle Screws on CT Scan Images: An Approach using a Digital Image Enhancement Technique
Jin Sup YEOM ; Moon Sang CHUNG ; Choon Ki LEE ; Whoan Jeang KIM ; Won Sik CHOY ; Jong Won KANG ; Yeong Ho KIM ; Nam Kug KIM ; Jae Bum LEE
Journal of Korean Society of Spine Surgery 2002;9(4):280-288
STUDY DESIGN: A study on the development of an algorithm to enhance computed tomographic images. OBJECTIVE: The purpose of this study was to develop an approach to reduce the metal artifact that appears around pedicle screws, and thus to facilitate the evaluation of pedicle screw positions on CT scan images. SUMMARY OF LITERATURE REVIEW: Metal artifact caused by pedicle screws significantly reduces the interpretability of computed tomography images. MATERIALS AND METHODS: We describe the development of an algorithm that processes CT scan images on a personal computer using a digital image enhancement technique. The algorithm improves CT images by transforming image pixel values using a proper transformation curve that takes into account the characteristic distribution pattern of metal artifact caused by pedicle screws made of titanium alloys. We implemented this algorithm in a program that reconstructs the resulting images in arbitrary planes and in axial, coronal, and sagittal planes. The software was tested with spiral CT scan images of 38 patients containing 190 pedicle screws. RESULTS: In all test cases, our algorithm generated images with less metal artifact, better soft tissue visualization and clearer screw outlines than conventional bone setting. In addition, images reconstructed in arbitrary planes increase the convenience and confidence of localizing screw positions. CONCLUSIONS: The algorithm effectively decreases metal artifact and improved pedicle screw localization.
Alloys
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Artifacts
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Humans
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Image Enhancement
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Microcomputers
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Titanium
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Tomography, Spiral Computed
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Tomography, X-Ray Computed
7.MDCT Application in the Vascular System
Journal of the Korean Medical Association 2007;50(1):25-32
Helical CT has improved with faster gantry rotation, more powerful X-ray tubes, and improved interpolation algorithms; however, the greatest advance has been made by the recent introduction of multi detector-row computed tomography (MDCT) scanners. Fundamental advantages of MDCT include substantially shorter acquisition times, retrospective creation of thinner or thicker sections from the same raw data, and improved threedimensional (3-D) rendering with diminished helical artifacts. While these features will likely be important to many applications of CT scanning, the greatest impact has been on CT angiography. The advantages of MDCT over single detector-row CT scanners when imaging the vascular system can be broken down into three fundamental improvements, that is, speed (faster scan time), distance (longer coverage), and section thickness (better resolution). This article will focus on how the MDCT technology has substantially improved imaging of the vascular system, including pulmonary artery, aorta and extremity vessels.
Angiography
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Aorta
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Artifacts
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Extremities
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Pulmonary Artery
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Retrospective Studies
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Tomography, Spiral Computed
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Tomography, X-Ray Computed
8.Central Lucency of Pelvic Phleboliths: Comparison of Plain Radiographs and Noncontrast Helical CT
Journal of the Korean Radiological Society 2000;43(1):81-85
PURPOSE: Central lucency of pelvic phleboliths is frequently observed on plain pelvic radiographs. When it is also present on noncontrast helical CT images, pelvic phleboliths may be easily diagnosed, with no suspicion of distal ureteral calculi. The objective of this study was to determine the frequency with which this phenome-non is seen on plain radiographs and noncontrast helical CT images.
Consensus
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Humans
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Radiography
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Renal Colic
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Tomography, Spiral Computed
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Tomography, X-Ray Computed
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Ureteral Calculi
9.Inflammatory Pseudotumor of the Spleen: A Case Report
Mee Eun KIM ; Hae wook PYUN ; Mi Ran KIM ; Hee Jin KIM ; Il Gee LEE ; Kyoung Rac SON
Journal of the Korean Radiological Society 2001;44(6):711-714
Inflammatory pseudotumor is a rare benign lesion consisting of inflammatory cells and fibroblastic stroma, and is reported to have occurred. in various organs. Splenic involvement, however, is extremely rare. We report the spiral CT findings of pathologically proven inflammatory pseudotumor of the spleen. The CT scan shows delayed enhancement with central, stellate, low attenuation.
Fibroblasts
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Granuloma, Plasma Cell
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Spleen
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Tomography, Spiral Computed
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Tomography, X-Ray Computed
10.The Factors Related to Local Recurrence after Radiofrequency Thermal Ablation of Hepatic Malignancies : Assessment of Spiral CT Findings
Woo Kyeong JEONG ; Hyunchul RHIM ; Yongsoo KIM ; Byung Hee KOH ; On Koo CHO ; Heung Seok SEO ; Kyung Bin JOO
Journal of the Korean Radiological Society 2002;46(5):473-478
PURPOSE: To determine the factors that are related to local recurrence after Radiofrequency thermal ablation (RFTA) of hepatic tumors. MATERIALS AND METHODS: We selected 30 patients with 51 hepatic nodules less than 5 cm in diameter (HCC, n=33; metastasis, n=18) who underwent RF thermal ablation between May 1999 and April 2000. Ablation was defined as 'complete'if immediately post-procedual CT showed that a nodule's margin was completely covered by ablation. Every three months, follow-up CT scans were examined for signs of local recurrence, and a nodule was assessed in terms of its size, the histologic diagnosis, adjacent vessels, perfect ablation (a safety margin of more than 5mm beyond the tumor margin), and whether hyperemia was observed after ablation. Finally, a group in which there was local recurrence (group A, n=15) and another showing no recurrence (group B, n=36) were compared. RESULTS: Mean nodule size in group A and group B was 3.26 and 2.24 cm, respectively. Local recurrence was noted in 7 of 33 HCC nodules (21.2%), and in 8 of 18 (44.4%) which were metastatic. There was recurrence in 9 of 31 nodules with adjacent vessels (29.0%), and in 6 of 20 (30%) without adjacent vessels. In two of 17 perfectly ablated nodules (11.8%) there was local recurrence, but this was observed in 13 of 34 imperfectly ablated nodules (38.2%). Finally, local recurrence was seen in 14 of 36 nodules showing hyperemia (38.9%) but in one of 15 (6.7%) without hyperemia. Using chi-square analysis, it was thus shown that with regard to local recurrence, tumor size, perfect ablation and peritumoral hyperemia were statistically significant factors (p<0.05). CONCLUSION: Local recurrence after RF thermal ablation of hepatic tumors clearly increases in nodules which are larger. The degree to which ablation is perfect, and the presence of peritumoral hyperemia, may be factors related to the local recurrence observed after RFTA.
Diagnosis
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Follow-Up Studies
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Humans
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Hyperemia
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Neoplasm Metastasis
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Recurrence
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Tomography, Spiral Computed
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Tomography, X-Ray Computed