The purpose of this study was to aid in the use of the digital images by edge-detect interpolation for direct digital periapical images using edge-deted interpolation. This study was performed by image processing of 20 digital periapical images; pixel replication, linear non-interpolation, linear interpolation, and edge-sensitive interpolation. The obtained results were as follows ; 1. Pixel replication showed blocking artifact and serious image distortion. 2. Linear interpolation showed smoothing effect on the edge. 3. Edge-sensitive interpolation overcame the smoothing effect on the edge and showed better image.
Artifacts

The dissection in forensic case is basically similar to any other sutopsy, with variations according to the nature of the death and the needs of the particular investigation. There are a number of manuals devoted to the performance of an autopsy and here only an outline of the technique to examining abdominal organs and described some postmortem artefacts. There are many facets of the autopsy, and there are a number of associated matters. Thus procedure of the autopsy is properly operated according to the circumstances.
Artifacts ; Autopsy*

PURPOSE: Among RF pulses, a sinc pulse is typically used for slice selection due to its frequency-selective feature. When a sinc pulse is implemented in practice, it needs to be apodized to avoid truncation artifacts at the expense of broadening the transition region of the excited-band profile. Here a sinc pulse tailored by a new apodization function is proposed that produces a sharper transition region with well suppression of truncation artifacts in comparison with conventional tailored sinc pulses. A multiband pulse designed using this newly apodized sinc pulse is also suggested inheriting the better performance of the newly apodized sinc pulse. MATERIALS AND METHODS: A new apodization function is introduced to taper a sinc pulse, playing a role to slightly shift the first zero-crossing of a tailored sinc pulse from the peak of the main lobe and thereby producing a narrower bandwidth as well as a sharper pass-band in the excitation profile. The newly apodized sinc pulse was also utilized to design a multiband pulse which inherits the performance of its constituent. Performances of the proposed sinc pulse and the multiband pulse generated with it were demonstrated by Bloch simulation and phantom imaging. RESULTS: In both simulations and experiments, the newly apodized sinc pulse yielded a narrower bandwidth and a sharper transition of the pass-band profile with a desirable degree of side-lobe suppression than the commonly used Hanning-windowed sinc pulse. The multiband pulse designed using the newly apodized sinc pulse also showed the better performance in multi-slice excitation than the one designed with the Hanning-windowed sinc pulse. CONCLUSION: The new tailored sinc pulse proposed here provides a better performance in slice (or slab) selection than conventional tailored sinc pulses. Thanks to the availability of analytical expression, it can also be utilized for multiband pulse design with great flexibility and readiness in implementation, transferring its better performance.
Artifacts ; Pliability

PURPOSE: We analyzed factors related to quality of photographs taken at neuroangiographic suites to optimize exposure condition. MATERIALS AND METHODS: We used a camera (EOS-300D, Canon Inc., Tokyo) with a standard- (EF-S 18-55 mm F3.5-5.6 USM, Canon Inc., Tokyo) and a macro-lens (EF 100 mm f/2.8 Macro USM, Canon Inc., Tokyo). Photographs were taken at a light-booth (1000 lux) and 2 neuroangiographic suites (988 and 856 lux) under ordinary intensity of illumination. We took photographs of a test chart (ColorChecker, X-rite, Michigan) and Kodak Q-13 Grey Scale Card at different values of aperture and shutter speed with fixed ISO of 400 and assessed the quality of photographs by Blade Pro (V1.1, Image group, Seoul). We analyzed photographs of a device at 1/25-1/80 shutter speed and F12 - 20 apertures and compared the result and also made visual assessment. RESULTS: Photographs of test chart and Grey Scale Card revealed that the best images chosen by Blade Pro were distributed in scattered range of quality which could help understand the range of optimum exposure condition but was not suitable for practical usage. We obtained reasonable quality photograph at shutter speed of 1/40 and aperture of F16 that can be used in 3 places. CONCLUSION: The most appropriate exposure condition when taking photographs in neuroangiographic suites could be explored. To get an optimal image in limited illumination, it is mandatory to select a fast enough shutter speed to avoid motion artifacts and a sufficient aperture to actualize the subject depth.
Artifacts ; Lighting

No abstract available.
Artifacts* ; Electrocardiography* ; Thyroidectomy*

PURPOSE: DIR image is relatively free from susceptibility artifacts therefore, DIR image can make it possible to reliably measure cortical thickness/volume. One drawback of the DIR acquisition is the long scan time to acquire the fully sampled 3D data set. To solve this problem, we applied a parallel imaging method (GRAPPA) and verify the reliability of using the volumetric study. MATERIALS AND METHODS: Six healthy volunteers (3 males and 3 females; age 25.33+/-2.25 years) underwent MRI using the 3D DIR sequence at a 3.0T Siemens Tim Trio MRI scanner. GRAPPA simulation was performed from the fully sampled data set for reduction factor 2. Data reconstruction was performed using MATLAB R2009b. Freesurfer v.4.3.0 was used to evaluate the cortical thickness of the entire brain, and to extract white matter information from the DIR image, Analyze 9.0 was used. The global cortical thickness estimated from the reconstructed image was compared with reference image by using a T-test in SPSS. RESULTS: Although reduced SNR and blurring are observed from the reconstructed image, in terms of segmentation the effect was not so significant. The volumetric result was validated that there were no significant differences in many cortical regions. CONCLUSION: This study was performed with DIR image for a volumetric MRI study. To solve the long scan time of 3D DIR imaging, we applied GRAPPA algorithm. According to the results, fast imaging can be done with reduction factor 2 with little loss of image quality at 3.0T.
Artifacts ; Brain ; Humans ; Male

PURPOSE: DIR image is relatively free from susceptibility artifacts therefore, DIR image can make it possible to reliably measure cortical thickness/volume. One drawback of the DIR acquisition is the long scan time to acquire the fully sampled 3D data set. To solve this problem, we applied a parallel imaging method (GRAPPA) and verify the reliability of using the volumetric study. MATERIALS AND METHODS: Six healthy volunteers (3 males and 3 females; age 25.33+/-2.25 years) underwent MRI using the 3D DIR sequence at a 3.0T Siemens Tim Trio MRI scanner. GRAPPA simulation was performed from the fully sampled data set for reduction factor 2. Data reconstruction was performed using MATLAB R2009b. Freesurfer v.4.3.0 was used to evaluate the cortical thickness of the entire brain, and to extract white matter information from the DIR image, Analyze 9.0 was used. The global cortical thickness estimated from the reconstructed image was compared with reference image by using a T-test in SPSS. RESULTS: Although reduced SNR and blurring are observed from the reconstructed image, in terms of segmentation the effect was not so significant. The volumetric result was validated that there were no significant differences in many cortical regions. CONCLUSION: This study was performed with DIR image for a volumetric MRI study. To solve the long scan time of 3D DIR imaging, we applied GRAPPA algorithm. According to the results, fast imaging can be done with reduction factor 2 with little loss of image quality at 3.0T.
Artifacts ; Brain ; Humans ; Male

Independent Component Analysis (ICA) is a signal processing algorithm to separate independent sources from unknown mixed signals and can be applied to separate artifacts and independent neural sources from EEG recordings. This study was designed to extract individual components of eyeball movements from scalp EEG. Digital EEG signals were recorded using the international 10-20 system during eye closure, eye opening, and blinking. 18 EEG tracings using bipolar montage were analyzed by ICA algorithm into 18 independent components. Each of the components was reviewed, selected, and reconstructed into an original montage. Among 18 components, two components which were thought to represent eyeball movements were obtained. Each of the components was inversely projected into the original bipolar montage. This inverse projection showed separated vertical and horizontal eyeball movements components. These results suggest that the ICA analysis of EEG can separate vertical and horizontal eyeball movements and may be applied to separate other EEG artifacts and source signals from unknown mixed sources recordings of EEG.
Artifacts ; Blinking ; Electroencephalography ; Scalp

Magnetic resonance imaging with its superior soft tissue contrast resolution and absence of beam hardening artifacts, combined with its ability to perform multiplanar imaging, is now effective tool in diagnostic imagings. Magnetic resonance is primarily a phenomenon that involves atomic nuclei. It provides totally new clinical informations with no known hazards through the use of very weak interactions with endogenous stable magnetic atomic nuclei. This article briefly summarized the basic mechanism of generation and detection of the signals and general sorts of tissue properties which can influence the signals and thereby give rise to tissue contrast. It also describes how the machine-operating parameters can be used to manipulate the tissue contrast observed in the image.
Artifacts ; Magnetic Resonance Imaging*

This paper introduces the basic theory and arithmetic of Independent Component Analysis which is a novel technology developed for Blind Source Separation. The Fast ICA arithmetic is applied as an example in analysis and separation of artifacts in clinical multiple channel EEG. The experiment results testify that by using ICA method artifacts in EEG such as EOG and power line interference can be separated and removed effectively.
Algorithms ; Artifacts ; Electroencephalography ; methods