年龄对肌肉超声图像纹理特征的影响

The effect of aging on texture features of muscle ultrasound images

目的:利用肌骨超声获得年轻人和老年人肌肉图像,分析肌肉形态学差异,并结合图像处理技术分析肌肉纹理特征随年龄的变化。方法:本试验于2018年5-7月招募健康成年志愿者50例,根据年龄分为青年组(<30岁)和老年组(≥60岁),青年组22例,老年组28例。使用肌骨超声获得两组志愿者内侧腓肠肌横切和纵切图像,直接测量肌肉厚度和羽状角。将所获得的图像进行兴趣区域的选择并从中提取9个纹理特征,包括基于灰度直方图的灰度均值和灰度方差;基于灰度共生矩阵的对比度和同质性;基于灰度梯度共生矩阵的灰度熵;基于游程长度矩阵的灰度不均匀性、游程长度不均匀性、低灰度游程优势和高灰度游程优势。结果:肌肉形态学上,老年组内侧腓肠肌肌肉厚度显著小于青年组(P<0.05),两组间羽状角无显著差异(P>0.05)。肌肉纹理上,与青年组相比,老年组的灰度方差、对比度、灰度熵、灰度不均匀性、低灰度游程优势显著降低(P<0.05);同质性、游程长度不均匀性显著增加(P<0.05)。两组间的灰度均值、高灰度游程优势无显著差异。结论:通过分析肌肉超声图像发现老年人有更大的同质性、游程长度不均匀性和更小的灰度方差、对比度、灰度熵、灰度不均匀性及低灰度游程优势。肌肉超声图像纹理分析技术能够反映肌肉内部组织随年龄增长的不利改变,可作为一种研究年龄相关的肌肉变化的生物学标志物。

Objective:Musculoskeletal ultrasound was used to acquire the muscle images of young and old people as well as measure the morphological differences of their muscles,associating with image processing to analyze the agerelated changes of muscle texture features.Method:Fifty healthy adult volunteers were recruited from May 2018 to July 2018,and divided into young group(<30 years,22 cases)and elderly group(≥60 years,28 cases)Musculoskeletal ultrasonography was used to acquire the transversal and longitudinal medial gastrocnemius ultrasonic images from two groups.Muscle thickness and pennation angle were measured directly.9 region of interests(ROIs)was selected from each image mean and variance of gray level,contrast and homogeneity of the gray level co-occurrence matrix,entropy of the gray level of gray gradient co-occurrence matrix,gray level non-uniformity,run length non-uniformity,low gray-level run emphasis and high gray-level run emphasis based on the run length matrix were analysed for each ROI..Result:In terms of muscle morphology,muscle thickness of the medial gastrocnemius significantly decreased in elderly group than the young one(P<0.05),and no significant difference was found in pennation angle between two groups(P>0.05).As for muscle texture,compared to the young group,variance,contrast,entropy,gray level non-uniformity and low gray-level run emphasis significantly decreased(P<0.05)while homogeneity and run length non-uniformity increased remarkably(P<0.05)in the elderly group.There was no significant difference between two groups in mean and high gray-level run emphasis(P>0.05).Conclusion:According to the assessment of muscle ultrasound images,older people had higher homogeneity and run length non-uniformity,lower variance,contrast,entropy,gray level non-uniformity and low gray-level run emphasis.Muscle ultrasonic image texture analysis can reflect the adverse changes of muscle structure with aging and may be used as a biomarker for studying the age-related muscle changes.