As computer programs for cephalometric analysis were developed in diagnosis & treatment planning, digital imaging of film-based cephalograms came to be needed. When a digital camera is used, a problem encountered is the image distortion produced according to the focal length, which causes errors in indentifying landmarks. In addition, changes in the image size and compression ratio will inevitably produce a low quality image, causing errors in identifying landmarks. Hence, we have found the focal length producing the least image distortion when digital imaging the film-based cephalograms and the minimal digital camera setting which helps to identify the correct landmarks using the COOLPIX4500 digital camera (Nikon, Japan). The results were as follows: The image distortion was minimized at a focal length of 16.4mm (79.4mm when converted into a 35mm film camera) when digital imaging the film-based cephalograms. When wide imaging, with a focal length of under 16.4mm, barrel distortion was found and when tele imaging, with a focal length of over 16.4mm, pincushion distortion was found. The minimal digital camera setting was 2272 X 1704 pixel at normal (1/8) compression from which we can identify the correct landmarks at the same level as tracing the film-based cephalograms manually. As a result, when digital imaging the film-based cephalograms, using a COOLPIX4500 digital camera (Nikon, Japan), the focal length should be 16.4mm, the pixel image size over 2272 X 1704, and the compression ratio over normal (1/8).
Diagnosis

OBJECTIVES: This study aims to find differences that reflect the magnitude of health disparities in wage workers in Korea according to income index(personal income, household income, equivalized income) by gender. METHODS: Data was obtained from the 11th wave of Korean Labor and Income Panel Survey in 2008. This study analyzed 4,205 subjects(2,570 males and 1,635 females) aged 19-65 years. To compare the health effects of each income index by gender, unconditional multiple logistic regression, health-related behaviors, and working conditions were used. The unconditional multiple logistic regression was adjusted by socio-demographic characteristics. All statistics were estimated using SAS survey procedures. RESULTS: According to unconditional multiple logistic regression, significant differences in ORs between men and women were observed in this study for those wage workers who self-rated their health status to be poor. This was consistent between each income index. Men had an OR of 1.76 (95% CI, 1.28~2.43) by personal income, 1.70 (95%CI, 1.25~2.32) by household income and 1.69 (95% CI, 1.23~2.31) by equivalized income. Women had an 2.09 (95% CI, 1.47~2.97) by household income and OR of 1.95 (95% CI, 1.36~2.79) by equivalized income, but personal income did not have a significant effect on OR for women. CONCLUSIONS: The study of occupational and environmental medicine should consider that each income index has different effects on the self-rated health status according to gender. Household income index and equivalized income index would represent a health status for women.
Aged ; Electrolytes ; Environmental Medicine ; Family Characteristics ; Female ; Humans ; Korea ; Logistic Models ; Male ; Phenothiazines ; Salaries and Fringe Benefits ; Socioeconomic Factors

BACKGROUND: Alendronate (AL), a drug for inhibiting osteoclast-mediated bone-resorption, was intercalated into an inorganic drug delivery nanovehicle, layered double hydroxide (LDH), to form a new nanohybrid, AL-LDH, with 1:1 heterostructure along the crystallographic C-axis. Based on the intercalation reaction strategy, the present AL-LDH drug delivery system (DDS) was realized with an enhanced drug efficacy of AL, which was confirmed by the improved proliferation and osteogenic differentiation of osteoblast-like cells (MG63). METHODS: The AL-LDH nanohybrid was synthesized by conventional ion-exchange reaction and characterized by powder X-ray diffraction (PXRD), high-resolution transmission electron microscopy (HR-TEM), and Fourier transform infrared (FT-IR) spectroscopy. Additionally, in vitro efficacy tests, such as cell proliferation and alkaline phosphatase (ALP) activity, were analyzed. RESULTS: The AL was successfully intercalated into LDH via ion-exchange reaction, and thus prepared AL-LDH DDS was X-ray single phasic and chemically well defined. The accumulated AL content in MG63 cells treated with the AL-LDH DDS nanoparticles was determined to be 10.6-fold higher than that within those treated with the intact AL after incubation for 1 hour, suggesting that intercellular permeation of AL was facilitated thanks to the hybridization with drug delivery vehicle, LDH. Furthermore, both in vitro proliferation level and ALP activity of MG63 treated with the present hybrid drug, AL-LDH, were found to be much more enhanced than those treated with the intact AL. This is surely due to the fact that LDH could deliver AL drug very efficiently, although LDH itself does not show any effect on proliferation and osteogenic differentiation of MG63 cells. CONCLUSION: The present AL-LDH could be considered as a promising DDS for improving efficacy of AL.
Alendronate ; Alkaline Phosphatase ; Cell Proliferation ; Drug Delivery Systems ; Fourier Analysis ; In Vitro Techniques ; Microscopy, Electron, Transmission ; Nanoparticles ; Spectrum Analysis ; X-Ray Diffraction

PURPOSE: The purpose of this study was to observe and analyze the effect of Methotrexate-Layered Double Hydroxide (LDH) hybrids on growth inhibition and the apoptosis of human osteosarcoma cell lines (SaOS-2, MG-63) and normal fibroblasts. MATERIALS AND METHODS: FITC-LDH hybrids were added to the cells and incubated for 2, 4, 6, and 8 hours. The samples were examined by fluorescence microscopy. SaOS-2 and MG-63 cells, and a normal fibroblast cell line (Detroit 551) were treated with 500 g/mL MTX and 500 g/mL MTX-LDH hybrids for 24, 48, 72, and 96 hours, respectively. The proliferation was measured by using the MTT assay. Apoptosis was determined by DNA fragmentation analysis. RESULTS: The hybrids with LDH entered the cells effectively in a time- and dose-dependent manner. The proliferation of SaOS-2 cells in a culture treated with 500 g/mL of MTX-LDH hybrids for 24 hours was significantly inhibited (37% more) compared to those treated with MTX. MG-63 cell growth was inhibited 20% more than SaOS-2 cell growth. However, the difference in the degrees of inhibition of cells treated with MTXLDH hybrid or with MTX alone reduced with time. DNA ladders appeared in cells treated with 500 g/mL MTX-LDH hybrid for 24 hours but not in those treated with MTX and LDH alone. CONCLUSIONS: The results of this study suggest that MTX-LDH hybrid more effectively enters cells and inhibits their proliferation than MTX alone.
Apoptosis ; Cell Line* ; DNA ; DNA Fragmentation ; Fibroblasts ; Humans ; Microscopy, Fluorescence ; Osteosarcoma*

PURPOSE: The purposes of this study were to develop an intraoperative navigation system as the first step toward image-guided surgery and robotic surgery, and to evaluate its accuracy. MATERIALS AND METHODS: The navigation system was composed of an optical tracking system (Polaris, Northern Digital) and a personal computer. The registration error and target localization error of fiducial registration and surface registration were measured using a phantom. Each of the errors was measured 30 times, and the average values and the standard deviations were calculated. RESULTS: The registration error was 0.84 +/- 0.28 mm at fiducial registration and 0.81 +/- 0.21 mm at surface registration. The target localization error was 1.54 +/- 0.34 mm at fiducial registration and 1.46 +/- 0.32 mm at surface registration. CONCLUSION: We have developed an intraoperative navigation system using an optical tracker, and could assure ourselves that its accuracy is adequate for many orthopaedic surgeries. However, it still requires improvement in the accuracy and development of specific software and instruments for various operations.
Microcomputers ; Surgery, Computer-Assisted

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 ; Artifacts* ; Humans ; Image Enhancement* ; Microcomputers ; Titanium* ; Tomography, Spiral Computed ; Tomography, X-Ray Computed*

STUDY DESIGN: The study involved the development and accuracy testing of an intra-operative navigation system. OBJECTIVES: This study was undertaken to develop a navigation system using a robot arm-type three-dimensional digitizer. And, to apply the developed system to pedicle screw insertion, and to evaluate its accuracy. SUMMARY OF LITERATURE REVIEW: To the best of our knowledge, no navigation system has been developed using a robot armtype three-dimensional digitizer. MATERIALS AND METHODS: We have developed a navigator using a three-dimensional digitizer (Microscribe 3-D G2, Immersion, USA) supported by a personal computer. Four types of patient-to-image registration techniques were implemented. During navigation, the central axis of the robot arm's stylus and arm extension can be displayed over multi-planar and three-dimensional images, which are reconstructed from axial CT scan images. Registration errors and target localization errors of the navigation system were evaluated using a phantom made from a plastic lumbo-sacral bone model. The accuracy of pedicle screw insertion was also evaluated by placing 18 pedicle screws in such bone models. RESULTS: The registration error was 0.78 +/- 0.27 mm at fiducial registration and 0.76 +/- 0.24 mm at hybrid registration, and the target localization error was 1.34 +/- 0.32 mm at fiducial registration and 1.28 +/- 0.29 mm at hybrid registration. Of the 18 screws placed in the plastic bone models, one (6%) screw breached the pedicle wall. CONCLUSIONS: We have developed a robot arm-type three-dimensional digitizer-based navigation system for pedicle screw insertion, and found that its accuracy is equal or slightly better than that of optical tracker-based navigators.
Arm ; Axis, Cervical Vertebra ; Feasibility Studies* ; Imaging, Three-Dimensional ; Immersion ; Microcomputers ; Plastics ; Tomography, X-Ray Computed

PURPOSE: This research aims at developing a simulation system for training of the correct placement of isometric points in arthroscopic reconstruction of anterior cruciate ligaments, using personal computer-based software and rapid prototyping knee models. MATERIALS AND METHODS: CT scan images of the knee joints of thirteen patients were used. Simulation software was developed on V-works(Clinic3D Inc.), a three-dimensional medical imaging system. Rapid prototyping models were made of hardened starch with a 0.178 mm slice thickness. RESULTS: In the first phase, trainee surgeons can study the positions of the bony attachments of healthy anterior cruciate ligaments, and compare their multiplanar reformatting images and a three-dimensional computer model of the bones. In the second phase, trainee sur-geons can place isometric points on the three-dimensional computer models and compare the results with the points set by a supervis-ing surgeon. Finally, rapid prototyping models, which are almost identical to the actual bones, are produced to allow the trainees to observe the isometric points marked on the models. CONCLUSION: Our system can provide a patient-specific simulation environment for beginners at arthroscopic anterior cruciate ligament reconstruction. It can be used as an educational and training tool for locating the isometric point of the anterior cruciate ligament during an operation.
Anterior Cruciate Ligament Reconstruction ; Anterior Cruciate Ligament* ; Computer Simulation* ; Diagnostic Imaging ; Humans ; Knee ; Knee Joint ; Starch ; Tomography, X-Ray Computed

PURPOSE: To analyze the results of radiologic and clinical outcomes after pedicle subtraction osteotomy in iatrogenic flat back syndrome. MATERIALS AND METHODS: We reviewed 12 surgical cases of iatrogenic flat back syndrome from January 1998 to July 2001 with a follow-up of more than 12 months. All cases were females and an average age was 59.8 years (48-66 years). An average follow-up period was20.4 months (12-37 months). Initial diagnosis were as follows: lumbar degenerative kyphosis, in 5 cases; spinal stenosis, in 5 cases; spondylolisthesis, in 2 cases. For clinical evaluation, 10-point pain scale and 5-point scale for activity level, cosmesis and subjective satisfaction were used. Lumbar lordotic angles and sagittal vertical axis (SVA) were measured. RESULTS: In radiologic results, an average lumbar lordotic angle at preoperative, postoperative and the last follow-up were 5.13+/-21.69 degree, -31.33+/-16.32 degree, -27.50+/-16.73 degree respectively. And average SVA at preoperative, postoperative and the last follow-up were 8.46+/-6.04 cm, 0.62+/-2.24 cm, 2.82+/-2.81 cm respectively. In clinical results, preoperative pain (6), activity (2) and cosmesis (1.8) were improved to 3.2, 3 and 3.2respectively at the last follow-up. Subjective satisfaction was 3.9. CONCLUSION: Pedicle subtraction osteotomy seemed to be very useful surgical option for improvement of clinical results through recovering of lumbar lordotic angle and sagittal balance in cases of iatrogenic flat back syndrome.
Axis, Cervical Vertebra ; Diagnosis ; Female ; Follow-Up Studies ; Humans ; Kyphosis ; Osteotomy* ; Spinal Stenosis ; Spondylolisthesis

Aims: Hundreds of uropathogenic Escherichia coli (UPEC) lineages with diverse virulence-associated traits have been reported worldwide. However, the complex interactions between the bacterial traits and host factors remain largely unexplored. This study was aimed to determine the distribution of virulence-associated traits, phylogenetic background and antimicrobial resistance profiles of the UPEC isolates in relation to the host factors. Methodology and results: Polymerase chain reactions (PCRs) were conducted to determine the prevalence of 32 virulence genes (VGs), eight pathogenicity island (PAI) markers and phylogroups of 105 UPEC isolates. The antimicrobial susceptibility testing was performed using the disc diffusion method. Results suggest that the virulenceassociated traits and antimicrobial resistance profiles of the UPEC strains were associated with phylogenetic background, host age and gender. Most of the virulence-associated traits tested were distributed prevalently in phylogroup B2, age group 40-59 and male gender, including papC, papG II_III, papG allele III, sfa/focDE, yfcV, hlyA, cnf1, cdtB, malX, PAI I536, PAI II536, PAI ICFT073, PAI IICFT073 and PAI IIJ96. Besides, higher rates of multidrug resistance (MDR) were significantly associated with non-phylogroup B2 (25/38; 65.8%; p<0.05) and age group 60-79 (29/42; 69.0%; p<0.05) but not with male gender (14/25; 56.0%; p=0.527). The UPEC strains collected from males and age 60-79 were significantly resistant to cefuroxime, cefotaxime and ceftazidime (all p<0.05). Conclusion, significance and impact of study Research findings elucidate the key molecular characteristics of the UPEC strains in relation to the host age and gender.