从脑部核磁共振成像（MRI）图像提取脑组织是影像学分析中的一项重要的预处理过程。提出了一种基于感兴趣区域和混合水平集方法的脑组织提取方法。该方法先采用脑组织提取工具（BET）方法得到脑组织的感兴趣区域，然后在该感兴趣区域内演化改进的混和水平集得到真实的脑组织边界。改进的混合水平集采用了一个非线性的速度函数，能够有效地防止边界泄露。该方法所用到的MRI数据均来自于IBSR（Internet brain segmentation repository web）网站。利用18组IBSR网站的MRI数据，该方法得到的结果接近于标准手动提取结果，并且在多个评价参数上都取得最好结果。实验结果表明该方法提取脑组织具有一定的准确性和稳定性。

Automatic extraction of brain tissue from MRI volume is an important step in the preprocessing of brain analysis. To improve the extraction result, a region of interest based method for automatic brain extraction was proposed. The first step of the proposed method was obtaining the brain region of interest with the brain extraction tool (BET) algorithm. Then a modified hybrid level set model was defined to obtain the true brain boundary. The modified hybrid level set model used a nonlinear speed function which can eliminate the boundary leakage effectively. 18 MRI volumes from internet brain segmentation repository (IBSR) were used in our experiment. The results obtained from our method were very similar with the results using manual extraction and almost achieved the best results on IBSR data compared with other methods. Experiment shows the proposed method is effective and robust.