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가설 설정
- Knowledge of the microstructual changes of the brain cortex would be helpful for difforaititing degenerative disease from normal aing. There have been reports that the cortical thickness shows linear changes according to aging (lf 2), and the cortical thickness decreased most significantly with age in the superior frontal area, and it showed a minimal difference in the gray matter (GM)/white matter(WM) ratio between men and women (3).
제안 방법
- In our study ( any gender differences in the TRGW and SRGW were not evident. In this study, there is basic limitation in the measurement of the thickness of the GM and WM because of lage voxel size compared with the object thickness itself, and it also has possibility of intraobserver variance according to the manual measurements.
- Using PACS tool, we measured whole thickness of the gyrus, and measured the thickness and the SI of the cortical GM and WM at the postcentral gyrus, where it has an even thickness at the level of centrum semiovale, on the axial scans (Figs. 1, 2), and we calculated the mean values of the thickness ratio of gray/white matter(TRGW) and the signal intensity ratio of gray/white matter(SRGW) in each age group, and we compared the ratios according to the age of the men and women ( Tables 1( 2). Statistical analysis was performed using Mest.
대상 데이터
- One hundred eighty patients (90 men and 90 women) who underwent routine brain MRI because of clinically suspected neurologic diseases, but who were diagnosed as normal on the basis of the MR findings and clinical follow up were selected for this study. The subject were grouped with 10 individuals of the age of 10f 20, 3Q 450; 60, 70, 80 and 90 for the men and women, spectivoly {a total of 18 groups).
- up were selected for this study. The subject were grouped with 10 individuals of the age of 10f 20, 3Q 450; 60, 70, 80 and 90 for the men and women, spectivoly {a total of 18 groups).
성능/효과
- The GM SI was decreased in the medial frontal area, and the WM SI was decreased in the superior and medial frontal areas, demonstrating decreased overall contrast with aging, and the GM/WM ratio was changed in the superior and inferior frontal areas (3). In our study, on the T2-weighted images, the contrast between the GM and WM was decreased in the aged brain due to decreased GM SI and increased WM SI. FLAIR is an inversion-recovery pulse sequence designed to nullify or greatly reduce the SI from CSF and brain parenchyma, but it can more clearly show parenchyma.
- On the FLAIR image, compared with the age of 10f the Sis at e e of 90 wew decreased 9% and 10% in le GM and they were increased 7% and 8% in the WM in the men and women respectively. The SRGWs were 1.
- 3). On the FLAIR images, the thickness of the gyrus was 7.3 mm and 7.2 mm at the age of 10, and 5.8 mm and 6.1 mm at the age of 70, and so it was decreased 21% and 15% for the whole thickness, with a 20% and 17% decrease of the GM, and a 22% and 13% decrease of the WM in the men and women, respectively. The TRGWs were 1.
- On the T2-weighted image, as compared with the age of 10, the Sis at the age of 90 were decreased 11% and 6% in the GM, and the Sis were increased 9% and 5% in the WM in the men and women, respectively. The SRGWs were 1.
- On the T2-weighted images, the thicknesses of the gyrus were 7.1 mm and 7.2 mm at the age of 10, and 5.4 mm and 5.1 mm at the age of 90 in men and women, respectively, and so the whole thickness was decreased 24% and 29%, with a 27% and 32% decrease of the GM and a 19% and 25% decrease of the WM in the men and women, respectively. The TRGWs were 0.
- On the Tl- weighted image, the thickness of the gyrus was 7.4 mm and 7.8 mm at the age of 10, and 5.6 mm and 5.9 mm at the age of 90, and so it decreased 24% and 24% for the whole thickness, with a 14% and 25% decrease of the GM and a 38% and 23% decrease of the WM in the men and women, respectively. The whole thickness of the gyrus was measured as 8% thicker on the Tl-weighted images than that on the T2-weighted images.
- On the Tl-weighted images, the Sis of the GM are increased 6% in the men and they were decreased 2% in the women, and the WM was increased 1% in the men and they were decreased 4% in the women, respectively. The SRGWs were 0.
- We excluded the images of the young children and the elderly subjects who had obvious high WM SI on the FLAIR images. The GM SI was decreased in the medial frontal area, and the WM SI was decreased in the superior and medial frontal areas, demonstrating decreased overall contrast with aging, and the GM/WM ratio was changed in the superior and inferior frontal areas (3). In our study, on the T2-weighted images, the contrast between the GM and WM was decreased in the aged brain due to decreased GM SI and increased WM SI.
- There have been reports that the cortical thickness shows linear changes according to aging (lf 2), and the cortical thickness decreased most significantly with age in the superior frontal area, and it showed a minimal difference in the gray matter (GM)/white matter(WM) ratio between men and women (3). The GM signal intensity(SI) was decreased with strong effects in the medial frontal area and the WM SI decreased in the superior and medial frontal areasf which demonstrated decreased overall contrast with aging in T1 weighted images. These findings may be an important biomarker of the pathologic changes with aging and according to disease j3).
- In the present study, the border became unclear after the age of 40f and the measurements of the GM and WM SI separately were not possible on the Tl-weighted images in 2 cases of the 80 and 90 year age groups, respectively. The patterns of change of the SI ratio on the T2-weighted and FLAIR images look similar with advancing age, and the ratios showed the highest value on the T2-weighted images and the lowest value on the Tl-weighted images. The causes of the SI change are considered to be decreased water content, an increased iron concentration etc.
후속연구
- We suggest that the agsl&ted microstructural changes of the xickness and the SI of the cortical GM and WM on the T2-f FLAIR and TLweiited images are unique, and so this knowledge will be helpful for differentiating between neurodegenerative disease and normal aging of the brain.
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