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P2–375: A new algorithm for brain tissue extraction and its evaluation for the assessment of cognitive decline in mild cognitive impairment and Alzheimer's disease
Author(s) -
Yamashita Fumio,
Nemoto Kiyotaka,
Matsuda Hiroshi,
Asada Takashi
Publication year - 2006
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2006.05.1215
Subject(s) - brain size , partial volume , alzheimer's disease , segmentation , thresholding , medicine , dementia , psychology , nuclear medicine , magnetic resonance imaging , audiology , disease , radiology , artificial intelligence , computer science , image (mathematics)
logical evaluations and resting [F-18]fluorodeoxyglucose (FDG) PET (mean interval 21.7 (SD 3.7) months), baseline structural 3T magnetic resonance (MR) imaging and apolipoprotein E (ApoE) genotyping. Five subjects were heterozygous for ApoE4, while 14 were ApoE3 homozygous. PET and MR scans were coregistered, and PET data were normalized to whole-brain average metabolism. Following 3D hemispheric MRI surface reconstruction, 38 sulci per hemisphere were traced and averaged for anatomically precise group mapping of PET data. Ratio maps of PET change data (time2/time1) were created. Results: Five subjects (26%), including one with ApoE4, were determined by the neuropsychologist to have significant decline on 2 or more neuropsychological tests—2 received diagnosis of mild cognitive impairment (MCI). Time1 vs. time2 comparisons across all subjects showed significant bilateral differences in posterior cingulate, precuneus, posterior temporal, lateral parietal, occipital and inferior frontal cortices. These changes did not significantly differ according to ApoE4 status. Ratio maps of test-decliners showed greater metabolic decline bilaterally in precuneus, posterior cingulate, lateral parietal, entorhinal as well as right middle/inferior frontal, temporal and occipital cortices, relative to ratio maps of non-test-decliners. Discussion: Using a sensitive 3D surface-based analytic technique for MR-guided neuroanatomic mapping of FDG-PET data, significant bilateral metabolic changes were identified in 6 brain regions, during aging of initially normal subjects. Changes in the bilateral posterior cingulate, precuneus and lateral parietal and the right temporo-occipital cortices were driven by the one-fourth of subjects who were test-decliners, and these were all regions in which hypometabolism has been previously identified in decliners from MCI to probable AD. In the test-decliner subgroup, metabolic changes were additionally identified in bilateral entorhinal and right middle frontal cortex. Longer clinical follow-up will help ascertain whether such a pattern of early metabolic decline can indeed serve as a specific predictor in individual subjects for ultimate progression to AD.