영상재구성 전산화 단층촬영에서 촬영조건의 변화가 하악골 술전 임플란트 부위 평가에 미치는 영향

김기덕,박창서 大韓口腔顎顔面 放射線學會 1999 Imaging Science in Dentistry Vol.29 No.1

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 predental 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.(J Korean Oral Maxillofac Radiol 1999:29:21-32)

약관절원판 천공의 방사선학적 연구

김기덕,박창서 大韓口腔顎顔面 放射線學會 1990 Imaging Science in Dentistry Vol.20 No.2

Thirty-nine patients (forty-four joints) who had been diagnosed as having meniscus perforation of the temporomandibular joint by inferior joint space arthrography and had been treated by surgical procedures were evaluated retrospectively. Information of clinical findings, arthrotomographic findings and surgical findings was collected on a standardized form and evaluated. The results were as follows : 1. On the 34 patients of 38 joints which were surgically confirmed perforation of meniscus or its attachments of the temporomandibular joint, there were 29 females and 5 males(5.8:1). The average age was 36 years(range 17 to 70). 2. The common clinical findings of group that had meniscus displacement without reduction and with perforation were pain on the affected joint and limitation of mouth opening. In the group showing meniscus displacement with reduction and with perforation the common clinical findings were pain and clicking on the affected joint. 3. 32 joints(84.2%) were arthrotomographically anterior meniscus displacement without reduction and with perforation, 6 joints(15.8%) showed anterior meniscus displacement with reduction and with perforation. 4. Joints categorized arthrotomographically as having meniscus displacement without reduction and with perforation were less likely to have full translation of the condyle in comparison with the normal or meniscus displacement with reduction and with perforation groups.(p<005) 5. The arthrographic findings of 44 joints having meniscus perforation were compared with surgical findings, there were 6 false positive findings of meniscus perforation, the reliability of arthrographic findings of meniscus perforation was a 86.4% correlation with surgical findings. 6. On the site of perforations of 38 joints which were surgically confirmed perforation of meniscus or its attachments, twenty-three of perforations(60.5%) were in location at the junction of the meniscus and posterior attachment, forteen(36.9%) were located at the posterior attachment and one (2.6%) was at the meniscus itself.

단층촬영 각도의 변화가 하악과두의 골 증식성 병소의 인식에 미치는 영향

김기덕,한상선 大韓口腔顎顔面 放射線學會 1999 Imaging Science in Dentistry Vol.29 No.1

Purpose: To find out the effects that different tomographic angles have on the osteophytic lesion detectability of condyle head by comparison the individualized lateral tomographic image with the various tomographic angled images using SCANORA . Materials & Methods: This study is performed to simulate osteophytic lesions by a series of dentin chips placed at six locations on condyle head. The control angle is 15°and from this angle, tomographic angle were varied with -10°, +10°+20°. All the images with each sized dentin chip were scored by three dental radiologists with the use of confidence levels for presence or absence of the lesion, each examiner viewed one of the images twice. A rating scale from 0 to 2 (0, lesion definitely not present; 1, uncertain if lesion is present; 2, lesion definitely present). Responses were assessed by Tukey's multiple comparison method and kappa value. Results: 1. The lesion size of 0.3mm could not be detected in all the tomographic angles. As the size of the lesion increased the average value of lesion detectability also increased. 2. In the lesion sizes of 0.7mm there was statistically significant difference between the 15°control angle and the altered tomographic angles (p<0.05). In 1.0mm lesion there was no significant difference in the ±10°altered angles (p<0.05), but there was significant difference in the altered angle(p<0.05). In the lesion sizes of 0.3mm and 2.0mm there was no significant difference between the 15°control angle and all the altered angle(p>0.05). 3. In the anteromedial, anterosuperior, anterolateral area there was no significant difference between the 15°control angle and the ±10°altered angle(p>0.05), but in the comparison with the +20°alterd angle there was significant difference(p>0.05). Conclusion: When imaging the lateral tomography of the temporomandibular joint used by SCANORA, it can be considered that in the osteophytic lesion size of 2mm and above, the tomographic angle difference within +20°to the horizontal angle of the condyle, has little effect on the lesion detectability. And in the lesion size of 1mm, the altered angle within ±10°also has little effect on the lesion detectability.

두개골의 3차원 영상 분석을 위한 전산화단층촬영 방법의 비교 : 상층 두께가 3차원 영상의 계측에 미치는 영향

정호걸,김기덕,박혁,김동욱,정해조,김희중,유선국,김용욱,박창서 대한구강악안면방사선학회 2004 Imaging Science in Dentistry Vol.34 No.3

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 Mathods : 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 (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 3mm, 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 7mm 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.

상층두께와 관심영역의 크기 변화가 CT번호에 미치는 영향

이지연,김기덕,박창서 대한구강악안면방사선학회 2001 Imaging Science in Dentistry Vol.31 No.2

Purpose : To evaluate the effect of the slice thickness and the size of region of interest (ROI) on CT number using quantitative CT phantom Materials and Methods : The phantom containing 150 mg/cc, 75 mg/cc and 0 mg/cc calcium hydroxyapatite was scanned with 1,3,5 and 10 mm slice thicknesses by single energy quantitative computed tomography (QCT). CT numbers were measured on center position of the phantom. Shape of ROI was circular and sizes were 1, 3, 5, 11, 16, 21, 26 and 33 mm2. ANOVA and Tukey's multiple comparison method were performed for statistical comparison of CT numbers according to different slice thicknesses. Coefficient of variation of CT number measured in each size of ROI was evaluated in same slice thickness. Results : CT numbers had statistically significant difference according to slice thicknesses (p〈0.05), As the slice thickness increased, CT number also increased. As the density of phantom became lower and the size of ROI became smaller, the coefficient of variation of CT number increased. When the size of ROI was more than 11 mm2 in 1 mm slice thickness, 5 mm2 in 3 mm slice thickness and 3 mm2 in 5 mm slice thickness, the coefficient of variation became consistent. In 10 mm slice thickness, the size of ROI had little effect on the coefficient of variation. Conclusion : CT number had variation according to the slice thickness and the size of ROI although the object was homogeneous. The slice thickness and the size of ROI are critical factors in precision of the CT number measurements.(Korean J Oral Maxillofac Radiol 2001;31:85-91)

악골에 발생한 백악질 및 골화성섬유종의 임상 및 방사선학적 고찰

박창서,김기덕,조은영 大韓口腔顎顔面放射線學會 1997 Imaging Science in Dentistry Vol.27 No.2

The purpose of this study was to know the proper diagnosis and to establish the treatment plan of cementifying and ossifying fibroma in the jaws through the clinical, raiological, and histopathologic considerations. The authors compared and analyzed the clinicoradiologic features of the thirteen cases of cementifying and ossifying fibroma, diagnosed at the Dental college hospital in Yonsei university, Seoul, Korea, during the period from 1980 to 1995. The obtained results were as follows: 1. Cementifying and ossifying fibroma occurred in the mean age, 44 years, ranged from 29 to 65 years and the male to female ratio was approximately 1:5. 2. Swelling was the most common frequent presenting complaints. Other reported symptoms included pain, tooth mobility and asymptom. 3. The frequency of the lesions was twelve cases in the mandible and one case in the maxilla. And eleven of thirteen cases were distributed on the premolar and molar region. 4. Radiologically, eight of thirteen cases were well defined lesions, five cases were relatively well defined lesions. And nine of thirteen cases were mixed lesions, three cases were radiopaque lesions, and only one case was purely radiolucenct lesion. 5. Histologically, seven of thirteen cases were classified ossifying fibroma, four cases were cemento-ossifying fibroma, and two cases were cementifying fibroma.

측두하악관절장애 환자의 자기공명영상에서 관찰되는 악관절 삼출

고지영,김기덕,박창서 대한구강악안면방사선학회 2001 Imaging Science in Dentistry Vol.31 No.2

Purpose : The purpose of this study was to find the relationship among the joint status, pain and effusion in patients with temporomandibular joint disorders. Materials and Methods : Materials included 406 patients (812 joints) with clinical records and bilateral TMJ MRIs in TMJ clinic, Yongdong Severance Hospital. All joints were classified in 4 groups in MR images according to the disc status of joint; normal disc position, disc displacement with reduction (DDcR), early and late stage of disc displacement without reduction (DDsR), and also 2 groups according to the bony status of joint; normal bony structure and osteoarthrosis. MR evidence of joint effusion was categorized in 4 groups according to its amount. To determine the relationship between joint pain and joint effusion, 289 patients with unilateral TMJ symptoms were selected from total materials. Result : Joint effusion was found 8.0% in normal disc position,32.6% in DDcR, and 59.2% in DDsR (83.1% in early state and 23.1% in late stage). Joint effusion was found 39.7% in osteoarthrosis and 35.0% in normal bony structure. Joint effusion was more found in the painful joints (49.8%) than in the painless joints (22.4%) (p 〈 0.001). Joint effusion in the early stage of DDsR only was more found significantly in painful joints (91.9%) than in painless joints (62,1%)(p〈 0.001). Conclusion : MR evidence of joint effusion might be related to disc displacement regardless of the presence of osteoarthrosis, and the early stage of DDsR was found more frequently combined with joint effusion and joint pain.(Korean J Oral Maxillofac Radiol 2001;31:73-84)

3차원 전산화단층촬영 영상을 이용한 얼굴 연조직 두께 계측

정호걸,김기덕,한승호,신동원,허경석,이제범,박혁,박창서 대한구강악안면방사선학회 2006 Imaging Science in Dentistry Vol.37 No.1

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. (Korean J Oral Maxillofac Radiol 2006; 36 : 49-54)

인공치아 이식부위 분석을 위한 다기능 영상체계의 실험적 검사

박창서,김기덕 大韓口腔顎顔面 放射線學會 1998 Imaging Science in Dentistry Vol.28 No.1

The ?? X-ray unit uses the principles of narrow beam radiography and spiral tomography. Starting with a panoramic overview as a scout image, multiple tomographic projections could be selected. This study evaluated the accuracy of spiral tomography in comparison to routine panoramic radiography for dental implant treatment planning. An experimental study was performed on a cadaver mandible to assess the accuracy of panoramic radiography and spiral tomography film images for measurement of metallic spheres. After radiographic images of the metallic spheres on the surgical stent were measured and corrected for a fixed magnification of radiographic images, following results were obtained. 1. In the optimal position of the mandible, the minimal horizontal and vertical distortion was evident in the panoramic radiography images. The mean horizontal and vertical magnification error in anterior sites was 5.25% and 0.75%, respectively. The mean horizontal and vertical magnification error in posterior sites was 0.50% and 1.50%, respectively. 2. In the displaced forward or in an eccentric position of the mandible, the magnification error of the panoramic radiography images increased significantly over the optimal position. Overall, the mean horizontal magnification error of the anterior site in the different positions changed dramatically within a range of -17.25% to 39.00%, compared to the posterior range of -5.25% to 8.50%. However, the mean vertical magnification error stayed with the range of 0.5% to 3.75% for all the mandibular positions.. 3. The magnification effects in the tomographic scans were nearly identical for the anterior and posterior with a range of 2.00% to 5.75% in the horizontal and 4.50% to 5.50% in the vertical dimension, respectively. 4. A statistically significant difference between the anterior and posterior measurements was found in the horizontal measurements of the panoramic radiography images of the displaced forward and backward position of the mandible(P<0.05). Also a significant difference between the optimal panoramic and tomographic projections was found only in the vertical measurement(P<0.05).

전산화단층촬영 단말장치와 개인용 컴퓨터에서 재구성한 두부 3차원 전산화단층영상의 비교

강복희,김기덕,박창서 대한구강악안면방사선학회 2001 Imaging Science in Dentistry Vol.31 No.1

Purpose : To evaluate the usefulness of the reconstructed 3-dimensional image on the personal computer in comparison with that of the CT workstation by quantitative comparison and analysis. Materials and Methods : The spiral CT data obtained from 27 persons were transferred from the CT workstation to a personal computer, and they were reconstructed as 3-dimensional image on the personal computer using V-works 2.OTM. One observer obtained the 14 measurements on the reconstructed 3-dimensional image on both the CT workstation and the personal computer. Paired t-test was used to evaluate the intraobserver difference and the mean value of the each measurement on the CT workstation and the personal computer. Pearson correlation analysis and % incongruence were also performed. Results : I-Gn, N-Gn, N-A, N-Ns, B-A, and G-Op did not show any statistically significant difference (p)0.05), B-O, B-N, Eu-Eu, Zy-Zy, Biw, D-D, Orbrd R, and L had statistically significant difference(p〈0.05), but the mean values of the differences of all measurements were below 2 mm, except for D-D. The value of correlation coefficient γ was greater than 0.95 at I-Gn, N-Gn, N-A, N-Ns, B-A, B-N, G-Op, Eu-Eu, Zy-Zy, and Biw, and it was 0.75 at B-O, 0.78 at D-D, and 0.82 at both Orbrd R and L. The % incongruence was below 4% at I-Gn, N-Gn, N-A, N-Ns, B-A, B-N, G-Op, Eu-Eu, Zy-Zy, and Biw, and 7.18%, 10.78%, 4.97%, 5.89% at B-O, D-D, Orbrd R and L respectively. Conclusion : It can be considered that the utilization of the personal computer has great usefulness in reconstruction of the 3-dimensional image when it comes to the economics, accessibility and convenience, except for thin bones and the landmarks which are difficult to be located.(Korean J Oral Maxillofac Radiol 2001;31:1-7)