探讨3T磁共振DTI成像技术及其参数在颈髓中的特点

Characteristics of DTI in the cervical spinal cord with 3T MR

目的:探讨3特斯拉(3T)磁共振弥散张量成像技术(DTI)作为一种定量分析方法在正常颈髓中的应用,分析正常颈髓的DTI参数和纤维束成像。方法:将21例健康成年志愿者平均分为3个年龄组行轴位DTI成像,对颈椎24、6、水平段脊髓的表观弥散系数(ADC)、分数各向异性(FA)、1λ、2λ、λ3值及不同年龄组的ADC、FA值进行统计学分析,并对所有志愿者行颈髓及其神经根神经纤维束成像。结果:ADC、FA图、颈髓及其神经根纤维束成像均显示良好。颈髓3个水平段的ADC值(F=0.04,P>0.957)、FA值(F=0.56,P>0.576)、1λ值(F=1.02,P>0.368)、2λ值(F=0.77,P>0.468)及λ3值(F=0.15,P>0.859)无统计学意义,不同年龄组间的ADC值(F=2.23,P=0.117)、FA值(F=0.11,P=0.899)无统计学意义。颈髓平均ADC值为(0.784±0.083)×10-3mm2/s、平均FA值为0.721±0.027、平均1λ、2λ、3λ值分别为(1.509±0.145)×10-3(、0.416±0.094)×10-3(、0.411±0.102)×10-3mm2/s。颈髓λ1值明显大于λ2、3λ值(P<0.05),λ2与λ3值无统计学意义(P>0.05)。结论:不同水平段正常成人颈髓呈上下方向的圆柱状弥散,ADC值和FA值是评价颈髓的敏感指标,神经纤维束成像能清晰显示颈髓及其神经根纤维束结构。

Objective： To explore the diffusion tensor imaging （DTI） as a quantitative analytic method in normal cervical spinal cord with 3T MR, and to obtain the standard apparent diffusion coefficient （ADC）, fractional anisotropy （FA） and fiber tracking in normal cervical spinal cords. Methods： Axial DTI of cervical spinal cords was performed on 21 healthy volunteers who were divided into three groups （younger than 30 years, 31 to 60 years, over 60 years） with GE EXCITE H 3.0T MR. The ADC, FA, λ1, λ2 and λ3 were measured at C2, C4 and C6 levels of normal cervical spinal cords. The data were analyzed with a software package SPSS 11.0. Fiber tracking was performed on these volunteers with functool software of the GE Company. Results： High quality ADC maps, FA maps and fiber tracking of cervical spinal cords were produced. There was no statistical significance in ADC （F = 0.04, P 〉 0.957）, FA（ F = 0. 56, P〉0.576）, λ1（F=1.02, P〉0.368）,λ2（F=0.77, P〉0.468）and λ3（F=0.15, P〉0.859）at C2, C4 and C6 levels of normal cervical spinal cords. There was also no statistical significance in ADC （ F = 2.23, P = 0. 117） and FA （F = 0. 11, P = 0. 899）among the three groups. The ADC, FA, λ1, λ2 and λ3 values were （0.784±0.083） × 10^-3mm^2/s）, 0.721 ±0.027, 1.509±0.145, 0.416±0.094, 0.411 ±0. 102 respectively in average. There was statistical significance among λ1,λ2 , and λ3 values （F = 1871.41, P =0）. The λ1 was significantly higher than λ2 （ Q = 74.75, P 〈 0.01 ） and λ3 （ Q = 75.10, P 〈 0.01 ）, and there was no statistical significance between λand λ3 values （ Q = 0. 347, P 〉 0.05）. Conclusions： The normal cervical spinal cord shows cylindrical diffusion at different levels and in different ages. ADC and FA values are sensitive indices for evaluating cervical spinal cords. The fiber tracing of cervical spinal cord is clearly demonstrated.