Della Nave R, Foresti S, Pratesi A, Ginestroni A, Inzitari M, Salvadori E, Giannelli M, Diciotti S, Inzitari D, Mascalchi M
Radiodiagnostic Section, Department of Clinical Physiopathology, University of Florence, Florence, and Medical Physics, Azienda Ospedaliera Universitaria Pisana, Pisa, Italy.
AJNR Am J Neuroradiol. 2007 Aug;28(7):1313-9. doi: 10.3174/ajnr.A0555.
Cerebral white matter changes, termed leukoaraiosis (LA), appearing as areas of increased signal intensity in T2-weighted MR images, are common in elderly subjects, but the possible correlation of LA with cognitive or motor deficit has not been established. We hypothesized that histogram and voxel-based analyses of whole-brain mean diffusivity (MD) and fractional anisotropy (FA) maps calculated from diffusion tensor imaging (DTI) could be more sensitive tools than visual scales to investigate the clinical correlates of LA.
Thirty-six patients of the Leukoaraiosis and Disability Study were evaluated with fluid-attenuated inversion recovery for LA extension, T1-weighted images for volume, and DTI for MD and FA. The extent of LA was rated visually. The normalized total, gray, and white matter brain volumes were computed, as well as the 25th percentile, 50th percentile, kurtosis, and skewness of the MD and FA maps of the whole brain. Finally, voxel-based analysis on the maps of gray and white matter volume, MD, and FA was performed with SPM2 software. Correlation analyses between visual or computerized data and motor or neuropsychologic scale scores were performed using the Spearman rank test and the SPM2 software.
The visual score correlated with some MD and FA histogram metrics (P<.01). However, only the 25th and 50th percentiles, kurtosis, and skewness of the MD and FA histograms correlated with motor or neuropsychologic deficits. Voxel-based analysis revealed a correlation (P<.05 corrected for multiple comparisons) between a large cluster of increased MD in the corpus callosum and pericallosal white matter and motor deficit.
These results are consistent with the hypothesis that histogram and voxel-based analyses of the whole-brain MD and FA maps are more sensitive tools than the visual evaluation for clinical correlation in patients with LA.
脑白质改变，即脑白质疏松（LA），在T2加权磁共振图像上表现为信号强度增加的区域，在老年人中很常见，但LA与认知或运动功能障碍之间的可能相关性尚未确立。我们假设，基于扩散张量成像（DTI）计算的全脑平均扩散率（MD）和分数各向异性（FA）图的直方图和体素分析，可能是比视觉量表更敏感的工具，用于研究LA的临床相关性。
对36例脑白质疏松与残疾研究患者进行了液体衰减反转恢复序列扫描以评估LA的范围，T1加权图像测量体积，DTI测量MD和FA。通过视觉对LA的范围进行评分。计算归一化后的全脑、灰质和白质脑体积，以及全脑MD和FA图的第25百分位数、第50百分位数、峰度和偏度。最后，使用SPM2软件对灰质和白质体积、MD和FA图进行基于体素的分析。使用Spearman秩检验和SPM2软件对视觉或计算机化数据与运动或神经心理量表评分之间进行相关性分析。
视觉评分与一些MD和FA直方图指标相关（P<0.01）。然而，只有MD和FA直方图的第25和第50百分位数、峰度和偏度与运动或神经心理缺陷相关。基于体素的分析显示，胼胝体和胼胝周白质中一大簇MD增加与运动功能障碍之间存在相关性（经多重比较校正后P<0.05）。
这些结果与以下假设一致，即基于全脑MD和FA图的直方图和体素分析是比视觉评估更敏感的工具，用于LA患者的临床相关性研究。
