Department of Radiology, Center for Molecular Imaging, University of Michigan, Ann Arbor, Michigan 48109-2200, USA.
Magn Reson Med. 2010 Nov;64(5):1499-509. doi: 10.1002/mrm.22507. Epub 2010 Sep 21.
The aim of this study was to empirically test the effect of chemotherapy-induced tissue changes in a glioma model as measured by several diffusion indices calculated from nonmonoexponential formalisms over a wide range of b-values. We also compared these results to the conventional two-point apparent diffusion coefficient calculation using nominal b-values. Diffusion-weighted imaging was performed over an extended range of b-values (120-4000 sec/mm(2) ) on intracerebral rat 9L gliomas before and after a single dose of 1,3-bis(2-chloroethyl)-1-nitrosourea. Diffusion indices from three formalisms of diffusion-weighted signal decay [(a) two-point analytical calculation using either low or high b-values, (b) a stretched exponential formalism, and (c) a biexponential fit] were tested for responsiveness to therapy-induced differences between control and treated groups. Diffusion indices sensitive to "fast diffusion" produced the largest response to treatment, which resulted in significant differences between groups. These trends were not observed for "slow diffusion" indices. Although the highest rate of response was observed from the biexponential formalism, this was not found to be significantly different from the conventional monoexponential apparent diffusion coefficient method. In conclusion, parameters from the more complicated nonmonoexponential formalisms did not provide additional sensitivity to treatment response in this glioma model beyond that observed from the two-point conventional monoexponential apparent diffusion coefficient method.
本研究旨在通过在宽 b 值范围内从非单指数公式计算的几个扩散指数来实证检验化疗诱导的神经胶质瘤模型中的组织变化的效果。我们还将这些结果与使用标称 b 值的常规两点表观扩散系数计算进行了比较。在单次 1,3-双(2-氯乙基)-1-亚硝脲给药前后，对颅内大鼠 9L 神经胶质瘤进行了扩散加权成像，b 值范围扩展至 120-4000 sec/mm(2)。使用三种扩散加权信号衰减的形式主义[（a）使用低或高 b 值的两点分析计算，（b）扩展指数形式主义，和（c）双指数拟合]测试了扩散指数对治疗引起的对照组和治疗组之间差异的反应性。对“快速扩散”敏感的扩散指数对治疗的反应最大，导致组间存在显著差异。这些趋势在“缓慢扩散”指数中没有观察到。尽管双指数形式主义观察到的响应率最高，但与传统的单指数表观扩散系数方法相比，这并没有发现显著差异。总之，在这种神经胶质瘤模型中，来自更复杂的非单指数形式主义的参数并没有提供比两点常规单指数表观扩散系数方法观察到的治疗反应更高的灵敏度。
