Effects of different sizes of Hydroxyapatite/beta-Tricalcium phosphate particles on vertical bone augmentation / 대한치과보철학회지

PURPOSE: This study was aimed to evaluate the effect of different sizes of beta-TCP/HA particles on vertical bone augmentation using titanium mesh in the cranium of rabbits. MATERIAL AND METHODS: Six white rabbits weighing 5kg were used. Four circular grooves of 6mm diameter were made by trephine, and five small holes were drilled in the inner surface of each circular gooves. Different sizes of grafts (small 0.3 - 0.5 mm, medium 0.5 - 1.0, large 1.0 - 2.0 mm) were placed respectively in the experimental groups. Titanium mesh (height 3 mm, width 6 mm) was placed. After 8weeks healing period, the rabbits were euthanized, and the specimens were prepared for histological findings. New bone formation and remaining graft area were measured to calculate the ratio of areas occupying the inner space of titanium mesh. Mann-Whitney U-test and Wilcoxon signed rank-test were used for statistical analysis (alpha = .05). RESULTS: The experimental groups with beta-TCP/HA graft showed a significantly higher new bone formation (P = .003). Comparing different sizes of beta-TCP/HA, there was no statistical difference in terms of new bone formation. The vertical bone formation (i.e. new bone and graft area) was significantly greater in beta-TCP/HA groups (P = .001). In comparison between different sizes of beta-TCP/HA, medium size group had significantly greater area than large particle size group (P = .039). CONCLUSION: The use of beta-TCP/HA with titanium mesh showed a higher vertical bone formation, particularly the medium sized beta-TCP/HA particles (0.5 - 1.0 mm) produced better results in vertical bone augmentation.

High-resolution CT Findings of Welders' Pneumoconiosis

PURPOSE: To describe the characteristic HRCT appearance and to evaluate the usefulness of HRCT in patients with welders' pneumoconiosis. MATERIALS AND METHODS: Chest radiographs and high-resolution computed tomography(HRCT) of 45 shipyard welders(male : female=41 : 4 ; age : 36-58 years, mean 47.8) with an occupational history of 4-25(mean 15.8) years were evaluated. Small rounded opacities in chest radiographs were read accordingto the ILO standard films(1980). HRCT were evaluated with micronodules, ground-glass attenuation, and other findings. Serial HRCT scans of seven welders taken 27 months apart were also evalauted. Two of these were still working in that job ; five had not worked as welders for 1-6(mean 4.4) years. RESULTS: HRCT of welders' pneumoconiosis showed poorly marginated centrilobular branching or dot opacities of low attenuation(n=36, 80.0%)with variable profusion and extent and ground-glass attenuation(n=8, 17.8%). HRCT abnormalities were seen in 39 welders(86.7%). It was able to depict micronodules(n=13) and/or ground-glass attenuation(n=3) in 15(68.2%) of 22welders with normal chest radiograph. Serial HRCT revealed no changes in parenchymal abnormalities(n=6) andslightly decreased profusion of micronodules(n=1). There was no HRCT abnormality suggesting gross parenchymal fibrosis. CONCLUSION: HRCT is more sensitive than chest radiography in detecting parenchymal changes in welders' pneumoconiosis, with characteristic poorly-marginated centrilobular branching opacities or dots and ground-glass attenuation. These HRCT appearances may be helpful in differentiating welders' pneumoconiosis from other diffuse lung diseases.

CT Findings of Silicosis

PURPOSE: To describe chest radiographic and CT findings of silicosis, and to compare their findings. MATERIALS AND METHODS: Ten coal miners and six stonemasons were included in this study. All were male and their mean age was 53.1. The mean duration of dust exposure was 15.2 years(range, 5-30 years) in coal miners and 25.3years(range, 15|35 years) in stonemasons. Chest radiographs(n=16), conventional CT scans(n=4), and high resolutionCT(HRCT) scans(n=13) were evaluated. Parenchymal abnormalities were interpreted on the basis of ILO standardfilms(1980) in chest radiographs and on the basis of CAP(College of American Pathologists, 1979) in CT(HRCT)films. RESULTS: Chest radiographs revealed large opacities(n=8), small opacities(n=6), and normal findings(n=2).Type r(n=4) and category 1/1(n=2) were most common for small opacities, while for large opacities, category B(n=4) and category c(n=4) were most common. These small and large opacities were located predominantly in the area of the upper and middle lung. Associated findings were emphysema(n=7), eggshell nodal calcifications(n=3), pneumothorax(n=3), C-P angle blunting(n=4), and pleural thickening(n=1). CT scans revealed micronodules(n=16), nodules(n=3), and progressive massive fibrosis(PMF, n=8). All these lesions were located in the upper and middlelungs, especially in the central portion of the posterior lung. PMF showed diffuse and homogenous(n=3) andpuntate(n=2) calcifications, cavitations(n=5), air bronchograms(n=3), and necrosis(n=1). Peripheral paracicatricalemphysema was associated with PMF(n=8). Other findings were pneumothorax(n=4), emphysema(n=10), hilar andmediastinal nodal enlargement(n=11), bronchial wall thick-enings(n=6), bronchiectasis(n=1), pleuralthickening(n=7), parenchymal fibrosis(n=1), and pulmonary tuberculosis(n=2). CONCLUSION: Small and large opacities in chest radiographs and micronodules, nodules, and PMFs in CT(HRCT) films were located predominately inthe upper and middle lungs, especially in the central portion of the posterior lung in CT films. CT was superiorto plain chest radiographs in the following ways : (1) in the early detection of small opacities, including subpleural micronodules, and in the precise evaluation of their concentration and topography ; (2) in the detection of cavitation or calcification within conglomerate large opacity lesions ; (3) in the detection of hilarand mediastinal nodal enlargements ; and (4) in quantitative assessment of the severity of emphysema.

Injection Method of Contrast Medium in Chest Spiral CT

PURPOSE: Authors studied the injection method of contrast medium in routine chest spiral CT scan to obtain the best image in the mediastinum. MATERIALS AND METHODS: Dynamic static scan had been performed in 5 normal volunteers as a pilot study. In consideration of the result of pilot study, Chest spiral CT was performed in 217 patients by three different methods. We used 100cc nonionic contrast medium. Average attenuation of great vessels in the mediastinum were assessed in various injection methods. Image quality was graded with three levels of score by two radiologists. RESULTS: Peak enhancement time of the great vessels on pilot at dynamic static scan were as follows :52 sec at ascending aorta, 45 sec at pulmonary artery, and 40 sec at SVC. In the study of spiral CT, the highest attenMarion in the great vessels was obtained after injection of 100cc of contrast medium(2cc/sec, with 35-40 second scan delay), althrough artifact from highly enhancing SVC was most common in this method. Image quality were highest in the scans obtained with other methods(3-2-1cc/sec for 10-15-40 seconds, with 40 second scan delay). CONCLUSION: For chest spiral CT, authors recommend that scans should be obtained after infusion of 70--80cc of contrast medium during 35--40sec to obtain maximal vascular enhacement of mediastinum.