fMRI investigation on cue-induced smoking craving.
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Brain↗
Biomedical subjects
Byung-Gil Choi
Publications and source records attributed to Byung-Gil Choi.
Head motion analysis during cognitive fMRI examination: application in patients with schizophrenia.
OBJECTIVES: Functional MRI (fMRI) has become an important imaging modality for analyzing the neural mechanisms underlying schizophrenia. Earlier studies indicate that patients with schizophrenia tend to generate involuntary and unnecessary head motion during visual tasks. Since head motion can deteriorate the quality of fMRI data, an investigation was needed to examine the type and extent of head motion from patients with schizophrenia undergoing fMRI. METHODS: Patients with schizophrenia and demographically-matched healthy comparison subjects underwent fMRI examination involving visual working memory tasks. We obtained head movement parameters (three translational and three rotational) through mathematical realignment of the volumetric image data, and transformed these parameters into head displacement indices to quantify the subject's head motion in space. RESULTS: We found no group difference in displacement indices between the two groups. Group comparison of movement parameters indicated that the patient group showed reduced head motion along the superior-inferior direction when compared to healthy individuals. CONCLUSION: These results suggest that cognitive fMRI examination in patients with schizophrenia can be successfully conducted without the deteriorative effects of head motion.
Adult↗
Working memory processing of facial images in schizophrenia: fMRI investigation.
Impaired processing of facial information is one of the broad ranges of cognitive deficits seen in patients with schizophrenia. This study aimed to elucidate the differences in brain activities involved in the process of facial working memory (images of neutral faces as mnemonic content) between schizophrenic patients and healthy comparison subjects using functional magnetic resonance imaging (fMRI). Group comparison analysis revealed aberrant activities from the patient group in several cortical areas, including the left fusiform gyrus, right superior frontal gyrus, bilateral middle frontal gyri/insula, and left middle temporal gyrus. A decreased level of activity in the left fusiform gyrus, along with performance reduction, implicates abnormal processing of facial information in schizophrenia.
Adult↗
Recovery from welding-fume-exposure-induced lung fibrosis and pulmonary function changes in sprague dawley rats.
Welder's pneumoconiosis has generally been determined as benign based on the absence of pulmonary function abnormalities in welders with marked radiographic abnormalities. Yet, there have also been several reports on welders with respiratory symptoms, indicating lung function impairment, X-ray abnormalities, and extensive fibrosis. Accordingly, this study attempted to investigate the inflammatory responses and pulmonary function changes in rats during a 60-day welding-fume-inhalation exposure period to elucidate the process of fibrosis. The rats were exposed to manual metal-arc stainless-steel welding fumes (MMA-SS) with total suspended particulate concentrations of 64.8 +/- 0.9 (low dose) and 107.8 +/- 2.6 mg/m3 (high dose) for 2 h per day in an inhalation chamber for 60 days. Animals were sacrificed after the initial 2-h exposure and after 15, 30, and 60 days, and the pulmonary function was also measured every week after the daily exposure. Elevated cellular differential counts were also measured in the acellular bronchoalveolar lavage fluid of the rats exposed to the MMA-SS fumes for 60 days. Among the pulmonary function test parameters, only the tidal volume showed a statistically significant and dose-dependent decrease after 35 to 60 days of MMA-SS welding-fume exposure. When the rats exposed to the welding fumes were left for 60 days to recover their lung function and cellular differentiation, recovery was observed in both the high and low-dose rats exposed up to 30 days, resulting in the disappearance of inflammatory cells and restoration of the tidal volume. The rats exposed for 60 days at the low dose also recovered from the inflammation and tidal volume loss, yet the rats exposed for 60 days at the high dose did not fully recover even after a 60-day recovery period. Therefore, when taken together, the results of the current study suggest that a decrease in the tidal volume could be used as an early indicator of pulmonary fibrosis induced by welding-fume exposure in Sprague Dawley rats, and fibrosis would seem to be preventable if the exposure is short-term and moderate.
Animals↗
Neuronal dysfunction of the frontal lobe in schizophrenia.
Localized in vivo proton magnetic resonance spectroscopy (MRS) was performed to evaluate metabolic alterations in the right and left frontal lobe before and after antipsychotic treatment of schizophrenic patients (n=24) and a group of healthy normal subjects (n=20). Proton metabolic ratios obtained from the 8 cm3 voxels in the right and left frontal lobes were compared with the clinical assessment for each subject. There was no significant difference in the metabolic ratios between the right and the left frontal lobes in either the schizophrenic group or the control group, indicating no laterality. Compared with those of the normal control group, NAA/Cr ratio of the schizophrenic patients showed significantly lower value. The NAA/Cr ratio of the schizophrenic patients was not changed after antipsychotic treatment. The present study supports the 'hypofrontality' hypothesis of schizophrenia.
Adolescent↗
Meniscal tear configurations: categorization with MR imaging.
OBJECTIVE: The purpose of this study was to evaluate the accuracy of MR imaging for categorizing the configuration of meniscal tears of the knee. MATERIALS AND METHODS: Fast spin-echo MR images obtained at 1.5 T from 110 patients who had meniscal tears identified at arthroscopy were retrospectively and independently classified by two reviewers into five configurations: horizontal, longitudinal, radial, oblique, and complex. MR imaging categorization was compared with arthroscopic results as the standard of reference. Data were also analyzed with longitudinal and oblique tears combined because these usually are reparable, and with horizontal, radial, and complex tears combined because these usually are not reparable. Interobserver and intraobserver agreements were calculated using kappa coefficients. RESULTS: At arthroscopy, meniscal tears were categorized as horizontal (n = 44), longitudinal (n = 34), complex (n = 22), radial (n = 11), and oblique (n = 5). Sensitivity, specificity, and accuracy of each reviewer for the reparable tears were 82%, 92%, and 89%; and 59%, 97%, and 84%, respectively. Interobserver agreements were fair between reviewer 1 and the first and second interpretations of reviewer 2 (kappa = 0.25, p < 0.005; and kappa = 0.21, p < 0.05, respectively). Intraobserver agreement was substantial (kappa = 0.71, p < 0.001). CONCLUSION: MR imaging was accurate for predicting reparable meniscal tears and was sensitive for the determination of nonreparable tears.
Adolescent↗