腰椎间盘退行性病变的MRI-DTI定量分析

目的探讨磁共振扩散张量成像(diffusion tensor imaging,DTI)相关测量指标作为定量分析方法在腰椎间盘病变的应用,并对扩散梯度方向对测量结果的影响进行研究。材料与方法选取来我院的腰腿疼患者50例,其中男32例,女18例,年龄24~62岁,平均年龄(46.9±16.2)岁,全部患者进行常规MRI及矢状位DTI腰椎间盘扫描,DTI扩散梯度方向分别为6、12、20。按扩散梯度方向将腰椎间盘分为DD6、DD12、DD20组;按Pfirrmann(Pm)分级将椎间盘分为Ⅱ、Ⅲ、Ⅳ及Ⅴ组,测量并比较不同扩散梯度方向组间、不同Pm分级组间椎间盘髓核区的表观扩散系数(apparent diffusion coefficient,ADC)、各项异向性分数(fractional anisotropy,FA)、纵向弥散系数(λ1)。结果不同扩散梯度方向组间ADC值差异无统计学意义(P0.05),而FA值、λ_1差异有统计学意义(P0.05);不同Pm分级组间,扩散梯度方向为6时,FA值在Ⅳ与Ⅴ组间差异无统计学意义(P0.05),其余分组间差异均有统计学意义(P0.05);扩散梯度方向为12和20时,FA值在Ⅱ与其他组间差异有统计学意义(P0.05),而Ⅲ、Ⅳ、Ⅴ组间差异无统计学意义(P0.05)。扩散梯度方向为6、12、20时,ADC值在Ⅱ、Ⅲ组间差异无统计学意义(P0.05),其余组间差异有统计学意义(P0.05)。在扩散梯度方向为6、12、20时,各组λ_1差异均无统计学意义(P0.05)。结论 DTI可应用于腰椎间盘病变的定量分析,扩散梯度方向为6时,可在较短的扫描时间内获得较高质量的图像及测量数据,并可应用FA值对不同Pm分级椎间盘进行定量分析。

Quantitative metabolites of lumbar intervertebral disc degeneration by diffusion tensor MR

Objective: To investigate the MR diffusion tensor imaging (DTI) as an application of quantitative analysis methods in lumbar intervertebral disc degeneration and the effects of different diffusion gradient directions (DGD) of DTI. Materials and Methods: Selected 50 patients with pain of waist or legs, including 32 male and 18 female, from 24 to 62 years old with mean age 46.9±16.2 years old, all the patients underwent sagittal scans for regular lumbar MRI and DTI, and with 6, 12, 20 DGD of DTI. According to the DGD, lumbar intervertebral discs can be divided into DD6, DD12, DD20 groups and divided lumbar intervertebral discs into Ⅱ, Ⅲ, Ⅳ, and Ⅴgroups by Pfirrmann grading system. ADC and FA and λ1 valuse were measured and analyzed among the different DGD groups and Pm groups. Results: There were no statistical difference of ADC values among the different DGD groups (P>0.05), while statistical difference of FA and λ1 values were found (P<0.05); DGD for 6, FA values were statistical differences among the different Pm groups (P<0.05), except Ⅳ andⅤ(P>0.05); DGD for 12 and 20, there were no statistical difference of FA values in all PM groups (P>0.05), except Ⅱ. DGD for 6, 12, 20, ADC values were statistical difference in all Pm groups, except Ⅱ and Ⅲ. In DGD for 6, 12, 20, λ1 values had no statistical difference in all Pm groups (P>0.05). Conclusion: DTI can be applied to the quantitative analysis of lumbar intervertebral disc, DGD for 6 can get high quality images and data in a relatively short time, and FA value can be used for quantitativeanalysis of different Pm grading lumbar intervertebral disc.