조기 알츠하이머 치매의 뇌포도당 대사 감소 평가에서 오류발견률 조절법의 적용

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 usingthe 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.