Qin Xulei, Fei Baowei
Department of Radiology and Imaging Sciences, Emory University, Atlanta, GA 30329, USA.
Phys Med Biol. 2014 Jul 21;59(14):3907-24. doi: 10.1088/0031-9155/59/14/3907. Epub 2014 Jun 24.
High-frequency ultrasound (HFU) has the ability to image both skeletal and cardiac muscles. The quantitative assessment of these myofiber orientations has a number of applications in both research and clinical examinations; however, difficulties arise due to the severe speckle noise contained in the HFU images. Thus, for the purpose of automatically measuring myofiber orientations from two-dimensional HFU images, we propose a two-step multiscale image decomposition method. It combines a nonlinear anisotropic diffusion filter and a coherence enhancing diffusion filter to extract myofibers. This method has been verified by ultrasound data from simulated phantoms, excised fiber phantoms, specimens of porcine hearts, and human skeletal muscles in vivo. The quantitative evaluations of both phantoms indicated that the myofiber measurements of our proposed method were more accurate than other methods. The myofiber orientations extracted from different layers of the porcine hearts matched the prediction of an established cardiac mode and demonstrated the feasibility of extracting cardiac myofiber orientations from HFU images ex vivo. Moreover, HFU also demonstrated the ability to measure myofiber orientations in vivo.
高频超声（HFU）能够对骨骼肌和心肌进行成像。这些肌纤维方向的定量评估在研究和临床检查中都有许多应用；然而，由于HFU图像中包含严重的斑点噪声，会出现一些困难。因此，为了从二维HFU图像中自动测量肌纤维方向，我们提出了一种两步多尺度图像分解方法。它结合了非线性各向异性扩散滤波器和相干增强扩散滤波器来提取肌纤维。该方法已通过来自模拟体模、切除的纤维体模、猪心脏标本和人体骨骼肌的超声数据得到验证。对两种体模的定量评估表明，我们提出的方法对肌纤维的测量比其他方法更准确。从猪心脏不同层提取的肌纤维方向与既定心脏模型的预测相符，证明了从离体HFU图像中提取心肌纤维方向的可行性。此外，HFU还证明了在体内测量肌纤维方向的能力。
