School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel.
Magn Reson Imaging. 2013 Sep;31(7):1097-104. doi: 10.1016/j.mri.2013.03.020. Epub 2013 May 6.
The brains of Long Evans shaker (les) rats, a model of dysmyelination, and their age- matched controls were studied by ex-vivo q-space diffusion imaging (QSI) and diffusion tensor imaging (DTI). The QSI and DTI indices were computed from the same acquisition. The les and the control brains were studied at different stages of maturation and disease progression. The mean displacement, the probability for zero displacement and kurtosis were computed from QSI data while the fractional anisotropy (FA) and the eigenvalues were computed from DTI. It was found that all QSI indices detect the les pathology, at all stages of maturation, while only some of the DTI indices could detect the les pathology. The QSI mean displacement was larger in the les group as compared with their age-matched controls while the probability for zero displacement and the kurtosis were both lower all indicating higher degree of restriction in the control brains. Since all the DTI eigenvalues were higher in the les brains as compared to controls, the less efficient DTI measure for discerning the les pathology was found to be the FA. Clearly, the most sensitive DTI parameter to the les pathology is λ3, i.e., the minimal diffusivity. Since the QSI and DTI data were obtained from the same acquisition, despite the somewhat higher SNR of the QSI data compared to the DTI data, it seems that the higher diagnostic capacity of the QSI data in this experimental model of dysmyelination, originates mainly from the higher diffusing weighting of the QSI data.
我们对长爪沙鼠震颤（les）模型的大脑进行了离体 q 空间扩散成像（QSI）和扩散张量成像（DTI）研究，并与年龄匹配的对照组进行了比较。QSI 和 DTI 指数均由相同的采集计算得出。les 和对照组的大脑在不同的成熟阶段和疾病进展阶段进行了研究。从 QSI 数据中计算出平均位移、零位移概率和峰度，而从 DTI 计算出各向异性分数（FA）和特征值。结果发现，所有 QSI 指数都可以检测到 les 病变，并且在所有成熟阶段均如此，而只有一些 DTI 指数可以检测到 les 病变。与年龄匹配的对照组相比，QSI 平均位移在 les 组中更大，而零位移概率和峰度均较低，这表明对照组大脑的限制程度更高。由于 les 大脑中的所有 DTI 特征值均高于对照组，因此发现 FA 是区分 les 病变的效率较低的 DTI 指标。显然，对于 les 病变最敏感的 DTI 参数是 λ3，即最小弥散度。由于 QSI 和 DTI 数据是从同一采集获得的，尽管 QSI 数据的 SNR 略高于 DTI 数据，但似乎在这种脱髓鞘实验模型中，QSI 数据的更高诊断能力主要源于 QSI 数据的更高扩散权重。
