正常尺神经肘段磁共振扩散张量成像研究

Experimental Research on MR Diffusion Tensor Imaging of the Elbow Part of Normal Ulnar Nerve

目的探讨磁共振扩散张量成像（DTI）技术在正常人尺神经肘段应用的可行性。方法采用GE Signa HDx 3.0T MR扫描仪,对23名健康志愿者（男16名,女7名,年龄2236岁,平均25.8岁）行常规MRI及DTI扫描,所得图像均应用工作站Functool diffusion tensor软件进行后处理,分别测量右肘关节间隙上1 cm、下1 cm及关节间隙水平三个不同层面尺神经的各向异性分数（FA）值、表观扩散系数（ADC）值。采用单次激发自旋回波平面回波成像（SE-EPI）序列分别测量b值为800、1000、1200 s/mm^2时,右尺神经肘段纤维束的体素大小、纤维束平均长度及图像的信噪比（SNR）。结果 23名健康志愿者接受DTI扫描,其中20名健康志愿者DTI及扩散张量纤维束示踪成像（DTT）成功;20名志愿者右肘关节间隙水平及其上、下1 cm三个层面尺神经平均FA值分别为0.72±0.07、0.76±0.03、0.71±0.06;ADC值分别为（0.98±0.115）×10^-3mm^2/s、（1.04±0.119）×10^-3mm^2/s、（0.93±0.134）×10^-3mm^2/s。右肘部不同水平层面尺神经FA值、ADC值两两比较均无统计学意义（P〉0.05）。b值=1000 s/mm^2时,右尺神经肘段平均纤维束长度及纤维所占体素最大（P〈0.05）。b值=800 s/mm^2时,SNR最大（19.16±6.87）（P〈0.05）;b值=1000 s/mm^2时,SNR是最大SNR的93%。结论 DTI、DTT成像技术对尺神经肘段应用具有可行性,能清晰显示尺神经肘段纤维束形态,可获得尺神经肘段的FA值、ADC值。采用3.0 T临床型MR机,尺神经肘段DTI、DTT成像技术优化的b值为1000 s/mm^2。

Objective To utilize MR diffusion tensor imaging（ DTI） of normal right elbow ulnar nerve to explore the feasibility of the applications of MR diffusion tensor imaging in normal elbow ulnar nerve with a 3. 0 T MR scanner. Methods Twenty-three healthy volunteers including 16 males and 7 females（ aged from 22 to 36 years old with a mean 25. 8 years old） were prospectively selected and underwent routine MRI and DTI scans by using a 3. 0-T MR scanner（ GE Signa HDx）. All the acquired images were reconstructed using the Functool Diffusion Tensor Software on the workstation. FA and ADC values of the ulnar nerve were measured at the levels of 1 cm upper,1 cm lower and the same level of the joint space of the right elbow,respectively. We used single-shot spin echo planar imaging sequence（ SE-EPI） to measure the average fiber bundles length,voxel of fiber bundles of the right elbow nerve and the SNR of images with b values of 800,1000,1200 s/mm^2. Results 23 healthy volunteers underwent DTI scans,in which 20 healthy volunteers underwent DTI and DTT scans successfully. FA values of the ulnar nerve at the levels of 1 cm upper,1 cm lower and the same level of the joint space of the right elbow of the 20 volunteers were 0. 72 ± 0. 07,0. 76 ± 0. 03,0. 71 ± 0. 06,respectively; ADC values were（ 0. 98 ±0. 115） × 10^-3mm^2/s,（ 1. 04 ± 0. 119） × 10^-3mm^2/s,（ 0. 93 ± 0. 134） × 10^-3mm^2/s,respectively. There were no statistically significant differences in FA and ADC values between each two groups of different levels of ulnar nerve. The average length of the fiber bundles and voxel of fiber bundles of the right elbow ulnar nerve reached the maximum when the b value= 1000 s/mm^2. SNR reached the maximum（ 19. 16 ± 6. 87） when b value = 800 s/mm^2. The SNR was 93% of the maximum SNR when b value = 1000 s/mm^2. Conclusion Magnetic resonance imaging technologies of DTI and DTT are feasible to evaluate the ulnar nerve. They can clearly delineate the morphology and obtain the FA and ADC values of the ulnar nerve fibers at the elbow. The optimized b value is 1000 s/mm^2 when using DTI,DTT imaging technologies for the ulnar nerve on a 3. 0 T MR scanner.