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Alzheimer's Disease, Other Dementia, Aging

開催日 2014/9/12
時間 14:00 - 15:00
会場 Poster / Exhibition(Event Hall B)

Age related alteration in the human brain tissue detected by T1-weighted/T2-weighted MR ratio image

  • P2-286
  • 石田 卓也 / Takuya Ishida:1 岩谷 潤 / Jun Iwatani:2 篠崎 和弘 / Kazuhiro Shinosaki:2 堂西 倫弘 / Tomohiro Donishi:1 寺田 正樹 / Masaki Terada:3 金桶 吉起 / Yoshiki Kaneoke:1 
  • 1:和歌山県立医科大学・第一生理 / Dept system neurophysiol,Wakayama Medical University 2:和歌山県立医科大学・精神科 / Dept psychiatry,Wakayama Medical University 3:和歌山南放射線クリニック / Wakayama-Minami Radiology Clinic 

Signal intensity value in MRI is arbitrary and the absolute value cannot be compared with other person's MRI values. Recently, Glasser and Van Essen suggested that the ratio of T1-weighted (T1w) and T2-weighed (T2w) MRI signal intensity cancels the receiver coil bias and increases the contrast related to myelin content, which was confirmed by our previous spinal cord MRI study. In this study, we tested if age-related brain tissue change could be detected by the T1w/T2w ratio image. Both T1w and T2w MRI were acquired with conventional parameters and then normalized with SPM8. The ratio image (voxel size of 6 mm) was created using in-house software developed on MATLAB for 33 healthy subjects (23-60 years old). At each voxel, correlation between signal intensity and age was calculated with Spearman's method. To correct for multiple comparison, we used Monte Carlo simulation to get corrected p<0.05. Significant negative correlations were found at corpus callosum, pyramidal tract, corona radiata, and left optic radiation in white matter and at insula, basal ganglia, cingulate gyrus, parieto-occipital cortex in the gray matter, which corresponded to the age-related myelin reduction as shown by the previous studies. Some regions identified in the gray matter were involved in the default mode network (DMN), which were considered to be related to Alzheimer's disease (AD). Significant positive correlations were found at right inferior frontal, left insular white matter, and right external capsule. Further analysis indicated that the signal intensity in these regions showed inverted U shaped change with age peaking at around 45 years old, suggesting biphasic developmental pattern of the myelination in these areas. The fact that the age-related signal intensity change could be detected by the T1w/T2w ratio image indicates the possibility of quantitative analysis of human normal brain and pathology of various brain diseases such as Alzheimer's disease, multiple sclerosis, and even psychiatric diseases using this imaging method.

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