目的 采用MR Dixon 技术评价 脊旁肌脂肪浸润，并探讨其与年龄的相 关性。方法 对135例患者Dixon脂肪和水 图像手绘包含脊旁肌的感兴趣区(region of interesting，ROI)2次，测量脊旁 肌的信号强度，计算脂肪信号分数(fat signal fraction，FSF)，采用协方差分 析(analysis of covariance,ANCOVA) 比较脊旁肌FSF与年龄的相关性，采用组 内相关系数(interclass correlation coefficences, ICCs)分析观察者间和观 察者内可靠性。结果 脊旁肌的FSF随年龄 增加上升，校正性别后，与年龄呈正相 关(R2=0.561, P=0.016)。观察者间和观 察者内可靠性良好(ICCs分别为0.83 和 0.86)。结论 MR Dixon 技术可以用于监 测脊旁肌随年龄增长发生的退行性变，并 且具有较高的可靠性。

Objective To assess paraspinal muscles fat infiltration by using Dixon MR imaging and investigate the relationship of fat infiltration with age. Methods Two radiologists measured signal intensity (SI) of right side paraspinal muscles by manual drawn ROI on fat and water images of Dixon sequence twice independently in 135 patients. The fat signal fraction (FSF) of paraspinal muscles was calculated. ICCs were used to evaluate inter- and intra-observers reliability. The relationship between FSF of paraspinal muscles and age was assessed using ANCOVA with adjustment of gender. Results FSF of paraspinal muscles increased with age. After adjusting gender, the association between FSF of paraspinal muscles and age was statistical significant (P=0.016). Inter- and intraobserver reliability was excellent with ICC of 0.83 and 0.86, respectively. Conclusion Dixon MR imaging can be used to monitor degeneration of paraspinal muscles with aging with excellent reliability.