Mezzapesa Domenico Maria, Rocca Maria Assunta, Pagani Elisabetta, Comi Giancarlo, Filippi Massimo
Neuroimaging Research Unit, Department of Neurology, Scientific Institute and University Ospedale San Raffaele, Via Olgettina 60, 20132 Milan, Italy.
Arch Neurol. 2003 Aug;60(8):1109-12. doi: 10.1001/archneur.60.8.1109.
To investigate whether additional "occult" tissue changes can be detected in the normal-appearing white matter and gray matter of otherwise normal elderly individuals with nonspecific white-matter hyperintensities on conventional magnetic resonance images of the brain.
Conventional and magnetization transfer magnetic resonance images were obtained from 12 otherwise normal elderly subjects with white-matter hyperintensities and 11 age- and sex-matched normal individuals. After automatic tissue segmentation, image coregistration, and masking of T2-visible lesions, we obtained magnetization transfer ratio histograms of the normal-appearing white matter and gray matter. For each histogram, the average magnetization transfer ratio, the peak height, and the peak position were measured. We also calculated the percentages of gray-matter and white-matter volumes normalized over the total volume of the intracranial content and the total normalized brain volumes.
Average magnetization transfer ratio (P =.03) and mean peak position (P =.01) of the gray-matter histograms from elderly individuals with white-matter hyperintensities were significantly lower than the corresponding quantities from those without white-matter hyperintensities. The normalized percentages of gray and white matter and normalized brain volume did not differ between the 2 groups. The average gray-matter magnetization transfer ratio was correlated with the average lesion magnetization transfer ratio (r = 0.68; P<.01).
This study shows that brain abnormalities in otherwise normal elderly subjects with nonspecific white-matter hyperintensities extend beyond the macroscopic white-matter lesions visualized on conventional magnetic resonance images.
探讨在常规脑磁共振成像上有非特异性白质高信号的正常老年个体中，是否能在看似正常的白质和灰质中检测到额外的“隐匿性”组织变化。
对12例有白质高信号的正常老年受试者和11例年龄及性别匹配的正常个体进行常规磁共振成像和磁化传递磁共振成像检查。在自动组织分割、图像配准以及对T2可见病变进行掩蔽后，我们获得了看似正常的白质和灰质的磁化传递率直方图。对于每个直方图，测量平均磁化传递率、峰值高度和峰值位置。我们还计算了灰质和白质体积占颅内内容总体积的归一化百分比以及归一化全脑体积。
有白质高信号的老年个体灰质直方图的平均磁化传递率（P = 0.03）和平均峰值位置（P = 0.01）显著低于无白质高信号个体的相应指标。两组之间灰质和白质的归一化百分比以及归一化脑体积没有差异。平均灰质磁化传递率与平均病变磁化传递率相关（r = 0.68；P < 0.01）。
本研究表明，在有非特异性白质高信号的正常老年受试者中，脑部异常超出了常规磁共振成像上可见的宏观白质病变范围。
