正常脑组织磁共振两b值及多b值扩散加权成像技术变异度对比分析

目的对比评估两b值及多b值扩散加权成像(diffusion weighted imaging,DWI)技术在正常脑组织中的变异度。材料与方法对29名正常脑组织行3.0 T GE磁共振两b值(0、1000 s/mm~2)及8b值(0、50 s/mm~2、100 s/mm~2、200 s/mm~2、400 s/mm~2、600 s/mm2、800 s/mm~2、1200 s/mm~2)DWI序列扫描,获取两b值参数表观扩散系数(apparent diffusion coefficient,ADC)值及多b值参数包括慢速ADC(D)、快速ADC(D*)、灌注相关体积分数ADC(f),应用变异系数评价脑组织各参数。结果脑组织的ADC值、D值、D*值、f值及其变异系数分别为:脑白质:(81.11±7.62)×10~(-5) mm/s,0.094;(78.47±6.72)×10~(-5) mm/s,0.086;(722.7±189.3)×10~(-5) mm/s,0.262;(8.97±3.63)%,0.404;脑皮质:(87.03±9.97)×10~(-5) mm/s,0.115;(81.83±7.51)×10~(-5) mm/s,0.092;(611.9±169.5)×10~(-5) mm/s,0.292;(9.55±3.41)%,0.357;基底节:(76.70±7.17)×10~(-5) mm/s,0.093;(73.72±6.40)×10~(-5) mm/s,0.087;(1221.9±743.4)×10~(-5) mm/s,0.608;(9.72±3.68)%,0.379。正常脑组织的ADC值及D值变异度接近且较低,而D*值及f值的变异度较高。结论多b值DWI技术获得的D值与两b值DWI技术获得的ADC值在正常脑组织具有同样低的变异度,而D*及f变异度较高,进行临床评价时结果需谨慎解读。

Variation analysis of diffusion weighted imaging in normal brain tissue between two b and multi-b value sequence

Objective: To observe the variation of two b and multi-b diffusion weighted imaging (DWI) in normal brain tissue. Materials and Methods: Apply two b and multi-b DWI sequence to 29 normal appearance brain using GE 3.0 T scanner. Two b and multi-b DWI related parameter including apparent diffusion coefficient (ADC), true diffusion (D), perfusion related diffusion (D*), fraction of perfusion (f) was acquired using AW workstation. The coefficient of variation (CV) of these parameters was compared to evaluate the reliability. Results:The values of CV of ADC, D, D* and f of brain were (81.11±7.62)×10-5 mm/s, 0.094; (78.47±6.72)×10-5 mm/s, 0.086; (722.7±189.3)×10-5 mm/s, 0.262; (8.97±3.63)%, 0.404 in white matter; and (87.03±9.97)×10-5 mm/s, 0.115; (81.83±7.51)×10-5 mm/s, 0.092; (611.9±169.5)×10-5 mm/s, 0.292; (9.55±3.41)%, 0.357 in gray matter; and (76.70±7.17)×10-5 mm/s, 0.093; (73.72±6.40)×10-5 mm/s, 0.087; (1221.9±743.4)×10-5 mm/s, 0.608; (9.72±3.68%), 0.379 in basal ganglia respectively. The CVs of ADC and D were similar and good and lower than others. Conclusion: D which derived from Multi-b DWI has good reliability as ADC which derived from two b DWI in normal brain. Otherwise, D* and f have higher variation in normal brains, and with which the comparison between individual should be explained with caution.