Cercignani M, Inglese M, Pagani E, Comi G, Filippi M
Neuroimaging Research Unit, Department of Neuroscience, Scientific Institute Ospedale San Raffaele and University Milan, Via Olgettina, 60, 20132 Milan, Italy.
AJNR Am J Neuroradiol. 2001 May;22(5):952-8.
Compared with conventional T2-weighted MR imaging, diffusion tensor MR imaging provides quantitative indices with increased specificity to the most destructive aspects of multiple sclerosis. In this study, we obtained brain mean diffusivity (_D) and fractional anisotropy histograms of patients with multiple sclerosis to compare them with those of healthy volunteers and to investigate the correlation between diffusion tensor MR imaging histogram-derived measures and the level of disability and quantities derived from conventional MR imaging.
Dual-echo and diffusion tensor MR images were obtained from 78 patients with relapsing-remitting, secondary progressive, or primary progressive multiple sclerosis and from 20 healthy control volunteers. After obtaining mean diffusivity (_D) and fractional anisotropy images and image coregistration, _D and fractional anisotropy histograms were created. From each histogram, the following measures were derived: the average _D and fractional anisotropy, the histogram peak heights, and the histogram peak locations.
All the _D and fractional anisotropy histogram-derived measures were different between patients and controls at a significance level of P <.001. No differences were found in any of the considered quantities among the three multiple sclerosis phenotypes. In patients with relapsing-remitting multiple sclerosis, disability was correlated with histogram average_D (r = 0.4, P =.01) and peak height (r = -0.4, P =.01). In patients with secondary progressive multiple sclerosis, disability was correlated with fractional anisotropy histogram peak position (r = -0.6, P =.01). Significant correlations were also found between T2 lesion load and various diffusion tensor MR quantities.
This study shows that brain _D and fractional anisotropy histograms are different for patients with multiple sclerosis compared with control volunteers. This study also shows that quantities derived from diffusion tensor MR imaging are correlated with disability in patients with relapsing-remitting multiple sclerosis and secondary progressive multiple sclerosis, suggesting that they might serve as additional measures of outcome when monitoring multiple sclerosis evolution in these patients.
与传统的T2加权磁共振成像相比，扩散张量磁共振成像提供了定量指标，对多发性硬化最具破坏性的方面具有更高的特异性。在本研究中，我们获取了多发性硬化患者的脑平均扩散率（_D）和分数各向异性直方图，将其与健康志愿者的进行比较，并研究扩散张量磁共振成像直方图衍生指标与残疾程度以及传统磁共振成像衍生指标之间的相关性。
对78例复发缓解型、继发进展型或原发进展型多发性硬化患者以及20名健康对照志愿者进行双回波和扩散张量磁共振成像检查。获取平均扩散率（_D）和分数各向异性图像并进行图像配准后，创建_D和分数各向异性直方图。从每个直方图中得出以下指标：平均_D和分数各向异性、直方图峰值高度以及直方图峰值位置。
在显著性水平P <.001时，患者与对照组之间所有_D和分数各向异性直方图衍生指标均存在差异。三种多发性硬化表型之间在所考虑的任何指标上均未发现差异。在复发缓解型多发性硬化患者中，残疾程度与直方图平均_D（r = 0.4，P =.01）和峰值高度（r = -0.4，P =.01）相关。在继发进展型多发性硬化患者中，残疾程度与分数各向异性直方图峰值位置（r = -0.6，P =.01）相关。T2病变负荷与各种扩散张量磁共振成像指标之间也存在显著相关性。
本研究表明，与对照志愿者相比，多发性硬化患者的脑_D和分数各向异性直方图存在差异。本研究还表明，扩散张量磁共振成像衍生指标与复发缓解型和继发进展型多发性硬化患者的残疾程度相关，这表明在监测这些患者的多发性硬化病情进展时，它们可能作为额外的预后指标。
