ABSTRACT
PURPOSE: Determining an appropriate thresholding is crucial for PDG PET analysis since strong control of Type I error could fail to find pathological differences between early Alzheimer' disease (AD) patients and healthy normal controls. We compared the SPM results on FDG PET imaging of early AD using uncorrected p-value, random-field based corrected p-value and false discovery rate (FDR) control. MATERIALS AND METHODS: Twenty-eight patients (66+/-7 years old) with early AD and 18 age-matched normal controls (68+/-6 years old) underwent FDG brain PET. To identify brain regions with hypo-metabolism in group or individual patient compared to normal controls, group images or each patient's image was compared with normal controls using the same fixed p-value of 0.001 on uncorrected thresholding, random-field based corrected thresholding and FDR control. RESULTS: The number of hypo-metabolic voxels was smallest in corrected p-value method, largest in uncorrected p-value method and intermediate in FDG thresholding in group analysis. Three types of result pattern were found. The first was that corrected p-value did not yield any voxel positive but FDR gave a few significantly hypometabolic voxels (8/28, 29%). The second was that both corrected p-value and FDR did not yield any positive region but numerous positive voxels were found with the threshold of uncorrected p-values (6/28, 21%). The last was that FDR was detected as many positive voxels as uncorrected p-value method (14/28, 50%). CONCLUSIONS: FDR control could identify hypo-metabolic areas in group or individual patients with early AD. We recommend FDR control instead of uncorrected or random-field corrected thresholding method to find the areas showing hypometabolism especially in small group or individual analysis of FDG PET.
Subject(s)
Humans , Brain , DementiaABSTRACT
OBJECTIVES: In order to investigate the effect of cultural and ethnic differences on the development of self-image, we conducted a cross-cultural study on Korean, Korean-Chinese and Chinese adolescents. METHODS: A total of 1576 Korean middle and high school students in Seoul/Choongju, 665 Korean-Chinese students and 634 Chinese students living in Yunbyun, China participated in this study. The Korean version of the Offer Self-Image Questionnaire was administered to Korean students, and the Chinese version of the questionnaire was administered to Korean-Chinese and Chinese students. The data obtained from all subjects were analyzed according to ethnicity and age variable through ANOVA. RESULTS: A significant difference across ethnicity was found in the 12 subscales and the total self-image score of OSIQ-R. Korean adolescents obtained significantly higher scores in all of the 11 subscales except the sexuality subscale than Korean-Chinese and Chinese adolescents. Korean-Chinese adolescents obtained significantly higher scores on the ethical value, idealism, family functioning, social functioning, impulse control, self-confidence and total self-image scores than Chinese adolescents, whereas Chinese adolescents obtained significantly higher scores in the subscales of emotional tone, sexuality, vocational attitudes, and self-reliance than Korean-Chinese adolescents. CONCLUSION: The results suggest the possibility that the difference in ethnicity(Korean versus Chinese), the tradition associated with each ethnic group, and the cultural-political factor(democracy versus socialism) significantly affects the development of self-image in adolescents. Although Korean-Chinese adolescents seemed to show cultural pluralism between Korean and Chinese cultures, they were similar to Korean adolescents in their tendency to respond in socially desirable ways, which suggests that although raised under the different cultural systems, traditional Korean ethical values were learned and internalized within the family.