腰椎间盘MR扩散张量成像及其定量分析

目的　研究正常成人腰椎间盘MR扩散张量成像及其量化特征。 方法 采用Philips 1.5T超导MR成像系统，对20例健康志愿者的L1/2～L5/S1椎间盘进行扫描，得到常规T1W、T2W，DTI扫描采用单次激发SE-EPI序列，扫描后处理获得纤维环示踪图（DTT）、FA彩图、FA图、e ADC图、Trance D图，观察DTT图上纤维环形态，通过ADC值、Trace D值、FA值的测量，定量分析纤维环、髓核的扩散特征。 结果　应用MR扩散张量成像可获取椎间盘纤维示踪图（DTT）、FA彩图、FA图、e ADC图、Trance D图，正常纤维环呈连续、规则均匀的环形，不同板层纤维束呈交错排列。纤维环的FA值显著高于髓核FA值(P<0.05)，髓核Trace值显著高于纤维环(P<0.05)，在髓核和纤维环内，轴向扩散高于放射状扩散　(P<0.05)，腰椎不同节段椎间盘内髓核、纤维环的扩散特征无显著性差别(P>0.05)。 结论　磁共振DTI能够显示纤维环内纤维束板层形态、排列；纤维环和髓核具有不同的扩散特征，纤维环的各向异性更显著，髓核更易于发生扩散；椎间盘内的主要扩散方向呈轴向。

MR diffusion tensor imaging and quantitative analysis of lumbar intervertebral disc

Objective To study the microstructure properties and quality analysis of human lumbar intervertebral disc by MR-DTI.Methods 20 healthy adults(20～57 years,averagely 37.4 years) were investigated under 1.5T Magnetic field.Imaging protocol included RF coil: CTL spine coil,Pulse sequence: Single-shot spin-echo echo planner imaging(SE-EPI),b-value: 600mm-2s,No.of gradient direction: 15,TE: 61 ms,TR: 3500 ms,No cardiac gating/VCG triggering,FOV: 48mm×139mm×80 mm,NEX: 3,Saturation pulse outside the region of interest(ROI),Shimming along the VOI.Results Higher FA in AF than NP suggested that diffusion in AF was more anisotropic than that in NP(P<0.05).The trace value in NP was higher than that in AF.This may suggested that the diffusion was more readily to take place in NP than in AF(Higher magnitude of diffusion in NP).In both AF and NP,the axial diffusivity was higher than the radial one,suggesting that diffusion in both medium was usually dominated in one direction,i.e.the axial direction.Conclusions The result gives an overview to the structure of IVD(AF and NP) based on their diffusion properties.The diffusion in AF is more anisotropic than that in NP.The diffusion is more readily to take place in NP than in AF.The diffusion in both medium is usually dominated in one direction,i.e.the axial direction.It is expected that in case of IVD disease,there will be structural damage to AF(AF tearing) and this will alter the local diffusion property.