Middleton Dana M, Li Jonathan Y, Chen Steven D, White Leonard E, Dickson Patricia I, Matthew Ellinwood N, Provenzale James M
1 Duke University School of Medicine, Durham, USA.
2 Department of Radiology, Duke University Medical Center, USA.
Neuroradiol J. 2017 Oct;30(5):454-460. doi: 10.1177/1971400917718844. Epub 2017 Jul 13.
Purpose We compared fractional anisotropy and radial diffusivity measurements between pediatric canines affected with mucopolysaccharidosis I and pediatric control canines. We hypothesized that lower fractional anisotropy and higher radial diffusivity values, consistent with dysmyelination, would be present in the mucopolysaccharidosis I cohort. Methods Six canine brains, three affected with mucopolysaccharidosis I and three unaffected, were euthanized at 7 weeks and imaged using a 7T small-animal magnetic resonance imaging system. Average fractional anisotropy and radial diffusivity values were calculated for four white-matter regions based on 100 regions of interest per region per specimen. A 95% confidence interval was calculated for each mean value. Results No difference was seen in fractional anisotropy or radial diffusivity values between mucopolysaccharidosis affected and unaffected brains in any region. In particular, the 95% confidence intervals for mucopolysaccharidosis affected and unaffected canines frequently overlapped for both fractional anisotropy and radial diffusivity measurements. In addition, in some brain regions a large range of fractional anisotropy and radial diffusivity values were seen within the same cohort. Conclusion The fractional anisotropy and radial diffusivity values of white matter did not differ between pediatric mucopolysaccharidosis affected canines and pediatric control canines. Possible explanations include: (a) a lack of white matter tissue differences between mucopolysaccharidosis affected and unaffected brains at early disease stages; (b) diffusion tensor imaging does not detect any existing differences; (c) inflammatory processes such as astrogliosis produce changes that offset the decreased fractional anisotropy values and increased radial diffusivity values that are expected in dysmyelination; and (d) our sample size was insufficient to detect differences. Further studies correlating diffusion tensor imaging findings to histology are warranted.
目的 我们比较了患有黏多糖贮积症I型的幼犬与对照幼犬之间的分数各向异性和径向扩散率测量值。我们假设，黏多糖贮积症I型队列中会出现与髓鞘形成异常一致的较低分数各向异性和较高径向扩散率值。方法 6只犬脑，3只患有黏多糖贮积症I型，3只未患病，在7周龄时实施安乐死，并使用7T小动物磁共振成像系统进行成像。基于每个样本每个区域100个感兴趣区域，计算四个白质区域的平均分数各向异性和径向扩散率值。为每个平均值计算95%置信区间。结果 在任何区域，黏多糖贮积症患病和未患病犬脑之间的分数各向异性或径向扩散率值均未观察到差异。特别是，黏多糖贮积症患病和未患病犬的95%置信区间在分数各向异性和径向扩散率测量中经常重叠。此外，在某些脑区，同一队列中观察到分数各向异性和径向扩散率值的较大范围。结论 患有黏多糖贮积症的幼犬与对照幼犬之间白质的分数各向异性和径向扩散率值没有差异。可能的解释包括：(a) 在疾病早期，黏多糖贮积症患病和未患病犬脑之间缺乏白质组织差异；(b) 扩散张量成像未检测到任何现有差异；(c) 诸如星形胶质细胞增生等炎症过程产生的变化抵消了髓鞘形成异常预期的分数各向异性值降低和径向扩散率值增加；(d) 我们的样本量不足以检测到差异。有必要进行进一步研究，将扩散张量成像结果与组织学相关联。
