PURPOSE: Localization using MRI is difficult due to susceptibility induced artifacts caused by metal electrodes. Here we took an advantage of the B0 pattern induced by the metal electrodes by using an oblique-view imaging method. MATERIALS AND METHODS: Metal electrode models with various diameters and susceptibilities were simulated to understand the aspect of field distortion. We set localization criteria for a turbo spin-echo (TSE) sequence usingconventional (90degrees view) and 45degrees oblique-view imaging method through simulation of images with various resolutions and validated the criteria usingphantom images acquired by a 3.0T clinical MRI system. For a gradient-refocused echo (GRE) sequence, which is relatively more sensitive to field inhomogeneity, we used phase images to find the center of electrode. RESULTS: There was least field inhomogeneity along the 45degrees line that penetrated the center of the electrode. Therefore, our criteria for the TSE sequence with 45degrees oblique-view was coincided regardless of susceptibility. And with 45degrees oblique-view angle images, pixel shifts were bidirectional so we can detect the location of electrodes even in low resolution. For the GRE sequence, the 45degrees oblique-view anglemethod madethe lines where field polarity changes become coincident to the Cartesian grid so the localization of the center coordinates was more facilitated. CONCLUSION: We suggested the method for accurate localization of electrode using 45degrees oblique-view angle imaging. It is expected to be a novelmethodto monitoring an electrophysiological brain study and brain neurosurgery.
Artifacts ; Brain ; Electrodes ; Imidazoles ; Magnetic Resonance Imaging ; Magnetic Resonance Spectroscopy ; Magnetics ; Magnets ; Neurosurgery ; Nitro Compounds

PURPOSE: Localization using MRI is difficult due to susceptibility induced artifacts caused by metal electrodes. Here we took an advantage of the B0 pattern induced by the metal electrodes by using an oblique-view imaging method. MATERIALS AND METHODS: Metal electrode models with various diameters and susceptibilities were simulated to understand the aspect of field distortion. We set localization criteria for a turbo spin-echo (TSE) sequence usingconventional (90degrees view) and 45degrees oblique-view imaging method through simulation of images with various resolutions and validated the criteria usingphantom images acquired by a 3.0T clinical MRI system. For a gradient-refocused echo (GRE) sequence, which is relatively more sensitive to field inhomogeneity, we used phase images to find the center of electrode. RESULTS: There was least field inhomogeneity along the 45degrees line that penetrated the center of the electrode. Therefore, our criteria for the TSE sequence with 45degrees oblique-view was coincided regardless of susceptibility. And with 45degrees oblique-view angle images, pixel shifts were bidirectional so we can detect the location of electrodes even in low resolution. For the GRE sequence, the 45degrees oblique-view anglemethod madethe lines where field polarity changes become coincident to the Cartesian grid so the localization of the center coordinates was more facilitated. CONCLUSION: We suggested the method for accurate localization of electrode using 45degrees oblique-view angle imaging. It is expected to be a novelmethodto monitoring an electrophysiological brain study and brain neurosurgery.
Artifacts ; Brain ; Electrodes ; Imidazoles ; Magnetic Resonance Imaging ; Magnetic Resonance Spectroscopy ; Magnetics ; Magnets ; Neurosurgery ; Nitro Compounds

BACKGROUND: This study was performed to evaluate the prevalence and risk factors on the adverse reactions caused by iodinated contrast media (CM) for computed tomography (CT) examination in a university hospital. METHODS: Clinical and demographic data among outpatients with CM use were collected at 0000 University Busanpaik Hospital in Busan, Korea between 2008 and 2010. Adverse reaction rate was calculated by the number of adverse reaction among total outpatients with CM use, which was stratified by seasons and sex. The association of risk factors on adverse reaction was investigated using logistic regression model. RESULTS: The total outpatients and events of administered CMs were 27,587 and 48,616, respectively. The administered CMs were iopromide, iohexol, iobitridol, and iodixanol. Adverse reactions occurred in 300 outpatients among the total outpatients (1.1 %). The number of outpatients administered CM more than twice were 8,348. Among them, outpatients who experienced adverse reaction(s) more than once and twice were 124 (1.5 %) and 26 (0.3 %), respectively. Adverse reaction rate was significantly different by sex(p=0.01). The other risk factors were cancer history (OR 2.57, 95 % CI 2.00-3.31) and previous CM administration (OR 1.89, 95 % CI 1.47-2.44). Urticaria was the most frequent symptoms. CONCLUSION: Total adverse reaction rate was 1.1 % with most common symptom in skin system. Related risk factors were female, cancer history, and previous CM administration. These results were similar to previous studies and will be contribute to clinical practice and future research especially in Koreans.
Contrast Media ; Female ; Humans ; Iohexol ; Korea ; Logistic Models ; Outpatients ; Prevalence ; Retrospective Studies ; Risk Factors ; Seasons ; Skin ; Triiodobenzoic Acids ; Urticaria

BACKGROUND: This study was performed to evaluate the prevalence and risk factors on the adverse reactions caused by iodinated contrast media (CM) for computed tomography (CT) examination in a university hospital. METHODS: Clinical and demographic data among outpatients with CM use were collected at 0000 University Busanpaik Hospital in Busan, Korea between 2008 and 2010. Adverse reaction rate was calculated by the number of adverse reaction among total outpatients with CM use, which was stratified by seasons and sex. The association of risk factors on adverse reaction was investigated using logistic regression model. RESULTS: The total outpatients and events of administered CMs were 27,587 and 48,616, respectively. The administered CMs were iopromide, iohexol, iobitridol, and iodixanol. Adverse reactions occurred in 300 outpatients among the total outpatients (1.1 %). The number of outpatients administered CM more than twice were 8,348. Among them, outpatients who experienced adverse reaction(s) more than once and twice were 124 (1.5 %) and 26 (0.3 %), respectively. Adverse reaction rate was significantly different by sex(p=0.01). The other risk factors were cancer history (OR 2.57, 95 % CI 2.00-3.31) and previous CM administration (OR 1.89, 95 % CI 1.47-2.44). Urticaria was the most frequent symptoms. CONCLUSION: Total adverse reaction rate was 1.1 % with most common symptom in skin system. Related risk factors were female, cancer history, and previous CM administration. These results were similar to previous studies and will be contribute to clinical practice and future research especially in Koreans.
Contrast Media ; Female ; Humans ; Iohexol ; Korea ; Logistic Models ; Outpatients ; Prevalence ; Retrospective Studies ; Risk Factors ; Seasons ; Skin ; Triiodobenzoic Acids ; Urticaria

OBJECTIVES: The aim of this study was to investigate brain activation during a Korean language-based 'theory of mind (TOM)' task and fMRI in Korean schizophrenic patients. METHODS: Fourteen Korean schizophrenic patients and 15 normal controls participated in this study. For all participants, several clinical states and psychosocial functions were evaluated. The subjects were then scanned while performing Korean language-based fMRI tasks. The tasks were comprised of conditions-first order false belief (TOM task), physical causality, and unrelated situations. Imaging data were analyzed using SPM2 software (uncorrected p<0.005, extent threshold kappa=10). RESULTS: 1) Compared with the control group, the patient group showed significantly poorer performance on the TOM task, and no significant correlation between TOM and empathic abilitiesy. 2) In the patient group, there were no significantly activated brain regions associated with the TOM task as compared to the physical causality task. With respect to between-group differences, the patient group showed significantly less activation of the left medial frontal region (primarily BA 8) and signifcantly different activation of the left precuneus (BA 7) associated with the TOM task. CONCLUSION: These results suggest that Korean schizophreniac patients show different brain activity associated with TOM functions, especially with respect to the Korean language-based first order false belief tasks.
Brain ; Humans ; Magnetic Resonance Imaging ; Schizophrenia ; Theory of Mind