结合MRF能量和模糊速度的乳腺癌图像分割方法

乳腺癌灶的精确分割是乳腺癌计算机辅助诊断的重要前提. 在动态对比增强核磁共振成像(Dynamic contrast-enhanced magnetic resonance imaging, DCE-MRI)的图像中, 乳腺癌灶具有对比度低、边界模糊及亮度不均匀等特点, 传统的活动轮廓模型方法很难取得准确的分割结果. 本文提出一种结合马尔科夫随机场(Markov random field, MRF)能量和模糊速度函数的活动轮廓模型的半自动分割方法来完成乳腺癌灶的分割, 相对于专业医生的手动分割, 本文方法具有速度快、可重复性高和分割结果相对客观等优点. 首先, 计算乳腺DCE-MRI图像的MRF能量, 以增强目标区域与周围背景的差异. 其次, 在能量图中计算每个像素点的后验概率, 建立基于后验概率驱动的活动轮廓模型区域项. 最后, 结合Gabor纹理特征、DCE-MRI时域特征和灰度特征构建模糊速度函数, 将其引入到活动轮廓模型中作为边缘检测项. 在乳腺癌灶边界处, 该速度函数趋向于零, 活动轮廓曲线停止演变, 完成对乳腺癌灶的分割. 实验结果表明, 所提出的方法有助于乳腺癌灶在DCE-MRI图像中的准确分割.

Segmentation of Breast Cancer on DCE-MRI Images With MRF Energy and Fuzzy Speed Function

Accurate segmentation of breast cancer is an important step for computer-aided diagnosis. In images obtained from dynamic contrast-enhanced magnetic resonance imaging technique, the traditional active contour model method is difficult to obtain accurate segmentation results due to the low contrast, blurred boundary and intensity inhomogeneous of the breast cancer images. In this paper, a semi-automatic segmentation of active contour model combining Markov random field (MRF) energy and fuzzy velocity function is proposed to perform the segmentation of breast cancer in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) images. This method has the advantages of fast speed, objectivity and the ability to reproduce the segmentation result compared to the manual segmentation of a professional doctor. First, the MRF energy of DCE-MRI is calculated to enhance the difference between the target area and the background. Second, the posterior probability of each pixel is calculated in the energy map. Then, region term of active contour model based on the posterior probability is developed. Finally, a fuzzy speed function, which derived by combining the image intensity, time domain characteristics of DCE-MRI and the Gabor texture feature, is introduced into the active contour model as edge function. At the boundary of breast cancer, the edge function approaches zero and the evolution of the contour curve will stop. The experimental results showed that the proposed segmentation method can accurately segment breast cancer in the images of DCE-MRI.