正常膝关节周围肌肉DTI纤维示踪成像b值探讨

The study of the optimal b-values in DTI fiber tracking in muscles around the knee

目的探讨膝关节周围肌肉DTI成像的最佳b值及相关参数。方法选取15例健康志愿者,男7例,女8例,年龄20～30岁,平均年龄25岁,行膝关节常规MR检查包括冠状T1WI、FS-T2WI,矢状位T2WI、PDWI及轴位T1WI,DTI(b值分别为400,500,700s/mm2)检查,重建出ADC图,eADC图,FA图及FA彩色编码图,通过DTI纤维示踪(fiber tracking)显示膝关节周围肌肉纤维束连续性和走行方向,分析比较不同b值情况下同一块肌肉肌纤维成像的清晰度与完整性,选择肌肉成像的最佳b值,并测量最佳b值时不同肌肉的ADC值、eADC值及FA值,分析不同肌肉同一b值的DTI参数有无差异。结果不同b值在同一块肌肉中成像质量有统计学差异,b值为500s/mm2的肌肉成像质量优于b值为400s/mm2,700s/mm2时的肌肉成像质量;b值为500s/mm2时不同肌肉的ADC值、eADC值及FA值无明显统计学差异。结论肌肉DTI成像最佳b值为500s/mm2,此时不同肌肉DTI参数无明显统计学差异。

Objective To assess the optimal h-value and reconstruction parameters for DTI and fiber tractography of the muscles around the knee. Methods Fifteen healthy volunteers（7 males, 8 females; mean age, 25. 5 years） were performed conventional MRI and DTI of knee at 3 T MRI scanner. The conventional MRI including coronal T1 WI, FS-Tz WI, sagittal T2WI, PDWI and axial T1WL DTI was acquired at four different b-values （400, 500, 600, 700 s/mmZ）. Apparent diffusion coefficient （ADC） map,exponent ADC （EADC） map, fractional anisotropy （FA） map, fractional anisotropy （FA） color-coded map were reconstructed and ADC,EADC, FA values were measured. Results The quality of fiber tract images of knee muscles were very different for different b-values. The image quality with b-value 500 was better than that of other b-values. There were no significant differences among ADC values, EADC values, and FA values for different muscles. Conclusion In conclusion, b value 500 s/mm2 was the optimal value for muscles around the knee,and there was not significant difference among DTI parameter with it in different muscles.