The quality of the images was better when b value=1000 s/mm2 was used,and noise became greater b balue=3000 s/mm2 .The more the number of the direction ,the greater the signal noise ration was not.

• 在b值组,以低b值所成图像较佳,其中以b值=1000s/mm2为最佳,而高b值所成图像噪声较大。 施加的弥散敏感梯度方向数并非越多越好,13个方向与21个方向所成图像没有明显差别,6个方向所成图像质量较差。