• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.67-75
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• 1999

The use of composite restorative materials is established due to continuing improvements in the materials and restorative techniques. Composite resins are widely used for the restoration of cervical lesions because of esthetics, good physical properties and working time. There are several types of cavity design for class V composite resin filling, but inappropriate cavity form may affect bonding failure, microleakage and fracture during mastication. Cavity preparations for composite materials should be as conservative as possible. The extent of the preparation is usually determined by the size, shape, and location of the defect. The design of the cavity preparation to receive a composite restoration may vary depending on several factors. In this study, 5 types of class V cavity were prepared on each maxillary central incisor. The types are; 1) V-shape, 2) round(U) shape, 3) box form, 4) box form with incisal bevel and 5) box form with incisal bevel and grooves for axial line angles. After restoration, in order to observe the concentration of stress at bonding surfaces of teeth and restorations, developing a 2-dimensional finite element model of labiopalatal section in tooth, surrounding bone, periodontal ligament and gingiva, based on the measurements by Wheeler, loading force from direction of 45 degrees from lingual side near the incisal edge was applied. This study analysed Von Mises stress with SuperSap finite element analysis program(Algor Interactive System, Inc.). The results were as follows : 1. Stress concentration was prevalent at tooth-resin bonding surface of cervical side on each model. 2. In model 2 without line angle, stress was distributed evenly. 3. Preparing bevel eliminated stress concentration much or less at line angle. 4. Model with round-shape distributed stress concentration more evenly than box-type model with sharp line angle, therefore decreased possibility of fracture. 5. Adding grooves to line angles had no effect of decreasing stress concentration to the area.

• Clinics in Shoulder and Elbow
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• v.15 no.2
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• pp.109-116
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• 2012

Purpose: The aim of this study was to evaluate preoperative ultrasonographic findings and usefulness in ulnar neuropathy around elbow. Materials and Methods: Twenty-two patients with ulnar neuropathy were performed preoperative ultrasonogram. The route, location, thickness of the ulnar nerve and space occupying lesion through longitudinal scan were evaluated. Cross-sectional areas of the ulnar nerve were measured at the level of medial epicondyle and 3 cm proximal and distal to the medial epicondyle through axial scan. Correlations between swelling ratio of ulnar nerve and eletrophysiologic study and preoperative Dellon's assessment were checked. Results: In 21 cases (95.6%) of total 22 cases, diffuse swelling of the ulnar nerve around elbow were identified. 4 cases had space occupying lesions including 3 ganglionic cysts and 1 heterotopic ossification. Cross sectional areas at the level of medial epicondyle were significantly larger than at the level of 3 cm proximal and distal to the medial epicondyle (p<0.05). There were no statistically significant correlations between swelling ratio of ulnar nerve and eletrophysiologic study and preoperative clinical assessment (p>0.05). Conclusion: This study showed that ultrasonography was helpful to detect etiology of ulnar neuropathy around elbow such as space occupying lesion, morphological change or dislocation of ulnar nerve. It could be useful tool for diagnosis and treatment in patients with ulnar neuropathy at elbow.

• Journal of the Korean Society of Radiology
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• v.16 no.1
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• pp.67-75
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• 2022

The aim of this study is to establish a new QC method that can simultaneously evaluate the resolution of the x/y plane and the z-axis by producing a phantom that can reflect exposure and reconstruction parameter of MDCT system. It was used with Aquilion ONE(Cannon Medical System, Otawara, Japan), and the examination was scanned using of 120 kV, 260 mA, and the D-FOV of 300 mm². It produced new SSP phantom modules in which two aluminum plates inclined at 45° to a vertical axis and a transverse axis to evaluate high contrast resolution of x/y plane and z axis. And it changed factors such as the algorithm, distance from gantry iso-center. All images were reconstructed in five steps from 0.6 mm to 10.0 mm slice thickness to measure resolution of x/y plane and z-axis. The image data measured FWHM and FWTM using Profile tool of Aquarius iNtusion Edition ver. 4.4.13 P6 software(Terarecon, California, USA), and analysed SPQI and signal intensity by ImageJ program(v1.53n, National Institutes of Health, USA). It decreased by 4.09~11.99%, 4.12~35.52%, and 4.70~37.64% in slice thickness of 2.5 mm, 5.0 mm, and 10.0 mm for evaluating the high contrast resolution of x/y plane according to distance from gantry iso-center. Therefore, the high contrast resolution of the x/y plane decreased when the distance from the iso-center increased or the slice thickness increased. Additionally, the slice thicknesses of 2.5 mm, 5.0 mm, and 10.0 mm with a high algorithm increased 74.83, 15.18 and 81.25%. The FWHM was almost constant on the measured SSP graph for evaluating the accuracy of slice thickness which represents the resolution of x/y plane and z-axis, but it was measured to be higher than the nominal slice thickness set by user. The FWHM and FWTM of z-axis with axial scan mode tended to increase significantly as the distance increased from gantry iso-center than the helical mode. Particularly, the thinner slice thickness that increased error range compare with the nominal slice thickness. The SPQI increased with thick slice thickness, and that was closer to 90% in the helical scan than the axial scan. In conclusion, by producing a phantom suitable for MDCT detectors and capable of quantitative resolution evaluation, it can be used as a specific method in the management of research quality and management of outdated equipment. Thus, it is expected to contribute greatly to the discrimination of lesions in the field of CT imaging.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.12-16
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• 2012

Purpose : In conventional PET image reconstruction, iterative reconstruction methods such as OSEM (Ordered Subsets Expectation Maximization) have now generally replaced traditional analytic methods such as filtered back-projection. This includes improvements in components of the system model geometry, fully 3D scatter and low noise randoms estimates. SharpIR algorithm is to improve PET image contrast to noise by incorporating information about the PET detector response into the 3D iterative reconstruction algorithm. The aim of this study is evaluation of SharpIR reconstruction method in PET/CT. Materials and Methods: For the measurement of detector response for the spatial resolution, a capillary tube was filled with FDG and scanned at varying distances from the iso-center (5, 10, 15, 20 cm). To measure image quality for contrast recovery, the NEMA IEC body phantom (Data Spectrum Corporation, Hillsborough, NC) with diameters of 1, 13, 17 and 22 for simulating hot and 28 and 37 mm for simulating cold lesions. A solution of 5.4 kBq/mL of $^{18}F$-FDG in water was used as a radioactive background obtaining a lesion of background ratio of 4.0. Images were reconstructed with VUE point HD and VUE point HD using SharpIR reconstruction algorithm. For the clinical evaluation, a whole body FDG scan acquired and to demonstrate contrast recovery, ROIs were drawn on a metabolic hot spot and also on a uniform region of the liver. Images were reconstructed with function of varying iteration number (1~10). Results: The result of increases axial distance from iso-center, full width at half maximum (FWHM) is also increasing in VUE point HD reconstruction image. Even showed an increasing distances constant FWHM. VUE point HD with SharpIR than VUE point HD showed improves contrast recovery in phantom and clinical study. Conclusion: By incorporating more information about the detector system response, the SharpIR algorithm improves the accuracy of underlying model used in VUE point HD. SharpIR algorithm improve spatial resolution for a line source in air, and improves contrast recovery at equivalent noise levels in phantoms and clinical studies. Therefore, SharpIR algorithm can be applied as through a longitudinal study will be useful in clinical.

• Korean Journal of Digital Imaging in Medicine
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• v.16 no.1
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• pp.13-19
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• 2014

Purpose: FLAIR image is beneficial for the diagnosis of various bran diseases including ischemic CVS, brain tumors and infections. However the border between the legion of brain metastasis and surrounding edema may not be clear. Therefore, this study aims to investigate the practical benefits of delayed imaging by comparing the image from a patient with brain metastasis before a contrast enhancement and the image 10 minutes after a contrast enhancement. Materials and methods: Of the 92 people who underwent MRI brain metastases in suspected patients 13 people in three patients there is no video to target the 37 people confirmed cases, and motion artifacts brain metastases in our hospital June-December 2013, 18 people measurement position except for the three incorrect patient (male: 11 people, female: 7 people, average age: 60 years) in the target, test equipment, 3.0T MR System (ACHIEVA Release, Philips, I was 8ChannelSENSE Head Coil use Best, and the Netherlands). TR 11000 ms, TE 125 ms, TI2800 ms, Slice Thickness 5 mm, gap 5 mm, is a Slice number 21, the parameters of the 3D FFE, T2 FLAIR variable that was used to test, TR 8.1 ms, TE 3.7 ms, Slice number 240 I set to. The experiment was conducted by acquiring the FLAIR prior to contrast enhancement (heretofore referred to as Pre FLAIR), and acquiring the 3D FFE CE five minutes after the contrast enhancement, and recomposing the images in an axial plane of S/T 3mm, G 0mm (heretofore referred to as MPR TRA CE). Using the FLAIR 10 minutes after the contrast enhancement (heretofore referred to as Post FLAIR) and Pi-View, a retrospective study was conducted. Using MRIcro on the image of a patient confirmed for his diagnosis, the images before and after the contrast media, as well as the CNR and SNR of the MPR TRA CE images of the lesion and the site absent of lesion were compared and analyzed using a one-way analysis of variance. Results: CNR for Pre FLAIR and Post FLAIR were 34.35 and 60.13, respectively, with MPR TRA CE at 23.77 showing no significant difference (p<0.050). Post-experiment analysis shows a difference between Pre FLAIR and Post FLAIR in terms of CNR (p<0.050), but no difference in CNR between Post FLAIR and MPR TRA CE (p>0.050), indicating that the contrast media had an effect only on Pre FLAIR and Post FLAIR. The SNR for the normal site Pre FLAIR was 106.43, and for the lesion site 140.79. Post FLAIR for the normal site was 107.79, and for the lesion site 167.91. MPR TRA CE for the normal site was 140.23 and for the lesion site 183.19, showing significant difference (p<0.050), and post-experiment analysis shows that there was a difference in SNR only on the lesion sites for Pre FLAIR and Post FLAIR (p<0.050). There was no difference in SNR between the normal site and lesion site for Post FLAIR and MPR TRA CE, indicating no effect from the contrast media (p>0.050). Conclusions: This experiment shows that Post FLAIR has a higher contrast than Pre FLAIR, and a higher SNR for lesions, It was not not statistically significant and MPR TRA CE but CNR came out high. Inspection of post-contrast which is used in a high magnetic field is frequently used images of 3D T1 but, since the signal of the contrast medium and the blood flow is included, this method can be diagnostic accuracy is reduced, it is believed that when used in combination with Post FLAIR, and that can provide video information added to the diagnosis of brain metastases.

• Investigative Magnetic Resonance Imaging
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• v.13 no.1
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• pp.81-87
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• 2009

Purpose : We sought to evaluate enhancement of plaque with gadolinium-based contrast agent by magnetic resonance imaging (MRI) in comparison with histopathology, namely lipid-rich and macrophage-rich components that were two representative characteristics of plaque vulnerability using atherosclerotic rabbit aorta in order to determine which histopathologic component is relevant to the enhancement. Materials and Methods : New Zealand white rabbit (n=4, weight 3.0 to 3.5 kg, all male) was used for animal model of atherosclerosis. Atherosclerotic aortic lesions were induced by high-cholesterol diet and double balloon injury. T1-weight axial images were acquired before and after gadolinium-based contrast agent using a 3-T MRI. MR images and the matched histopathological sections (n=35) were divided into 4 quadrants or 3 (n=130). Enhancement ratio (ER, ER=SIpost/SIpre) on MRI was calculated for each quadrant and compared with histopathology in regard to lipid-rich and macrophage-rich areas. Results : Lipid-rich quadrants were 72 and fibrous quadrants were 58. The number of quadrants which had macrophage-rich areas was 105 and that of quadrants which did not have macrophage-rich areas was 25. ER was significantly higher in lipid-rich quadrants than in fibrous quadrants (mean ER 2.25c$\pm$0.41 vs. 2.72$\pm$0.65, p=0.013). ER poorly correlated with macrophage-rich areas when lipid-component was controlled (correlation coefficient -0.203, p=0.236). Conclusion : Lipid-rich plaques showed stronger enhancement than fibrous plaques using a standard gadolinium-based extracellular contrast agent. Macrophage infiltration did not correlate with degree of enhancement. Further study is warranted that account for optimal time of imaging after contrast injection using various plaque models from early to advanced stages and all possible parameters associated with contrast enhancement.

• Journal of Korean Society of Spine Surgery
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• v.25 no.4
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• pp.147-153
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• 2018

Study Design: Retrospective case series. Objectives: We retrospectively evaluated the clinical efficacy of postganglionic nerve block in symptomatic Schmorl nodules (SNs). Summary of Literature Review: SNs are common lesions that are often asymptomatic. In certain cases, SNs have been reported to cause severe axial back pain, thereby considerably impacting patients' quality of life. No consensus currently exists on the treatment of symptomatic SNs. Materials and Methods: From October 2015 to October 2017, a total of 21 patients with symptomatic SNs diagnosed by magnetic resonance imaging (MRI) that did not respond to conservative treatment after 4 weeks were included in the study. All patients received postganglionic nerve block. We evaluated effective pain relief (improvement of back pain of more than 50% compared with before the intervention) and functional improvements, assessed by visual analogue scale (VAS) and Oswestry Disability Index scores obtained at 4 hours, 4 weeks, 8 weeks, 3 months, and 6 months after the procedure. Results: Symptomatic SNs were more common at the L2-3 level, and the lower end plate was more commonly involved than the upper end plate. Eighteen of the 21 patients (85.7%) showed effective pain relief, and no deterioration was observed within the followup period. Throughout the follow-up period, the VAS remained significantly improved compared to before the procedure (p<0.05). Complications were not reported in any cases. Conclusions: Postganglionic nerve block for symptomatic SNs that do not respond to conservative treatment is a non-invasive modality for pain relief.