中文摘要：

许多研究证明了有散开 weighting (b 因素) 的一个 extend 范围的磁性的回声信号腐烂是在在 vivo 的散开加权的磁性的回声成像实验的双性人指数的变细。基于这个特征和二分割为若干部分的模型，我们建议一个 twice-linear-fitting (TLF ) 算法估计水分子的明显的散开系数(模数转换器) 而不是通常使用的反复的 LevenbergMarquardt (LM ) 方法。TLF 算法由适合步估计的二架班机组成快并且慢明显的散开系数和他们的尺寸分别地。在完整的适合过程猜测起始的价值是不必要的。TLF 算法的时间消费多不到反复的 LM 方法的。而且， TLF 算法可以避免体外的答案，它经常败坏 LM 方法的结果。与反复的适合方法相比， TLF 算法是一条可靠、时间有效的途径在散开加权的成像试验的磁性的回声在 vivo 估计水分子的模数转换器。

英文摘要：

Many studies have shown that the magnetic resonance signal decay with an extend range of diffusion weighting （b-factor） is a bi-exponential attenuation in the diffusion-weighted magnetic resonance imaging experi- ments in vivo. Based on this feature and the two-com- partmental model, we propose a twice-linear-fitting （TLF） algorithm to estimate the apparent diffusion coefficient （ADC） of the water molecules instead of the commonly used iterative Levenberg-Marquardt （LM） method. The TLF algorithm consists of two liner fitting steps to estimate the fast and the slow apparent diffusion coefficients and their sizes, respectively. It is unnecessary to guess the initial values in the whole fitting process. The time con- sumption of the TLF algorithm is much less than that of the iterative LM method. Moreover, the TLF algorithm may avoid the extraneous solutions, which often deteriorates the results of the LM method. Compared with the iterative fitting method, the TLF algorithm is a reliable and time- efficient approach to estimate the ADC of water molecules in vivo in magnetic resonance diffusion-weighted imaging experiments.