放射学孤立综合征的MR扩散张量成像研究

The study of radiologically isolated syndrome using MR diffusion tensor imaging

目的 应用MR DTI技术研究放射学孤立综合征（RIS）患者在常规MRI上表现正常的脑白质（NAWM）是否存在异常.方法 收集RIS患者27例（RIS组）,同时选取16名年龄和性别均与RIS组相匹配的常规头颅MR检查无明显异常的健康志愿者（正常对照组）,2组患者均行头颅常规MRI及DTI横断面扫描.测量受试者胼胝体膝部、体前部、体后部、压部以及额叶白质、枕叶白质的各向异性分数（FA）值、平均扩散系数（MD）值.2组之间不同区域的FA值、MD值比较采用独立样本t检验,同一研究者的2次测量值采用类内相关系数（ICC）分析.结果 同一研究者2次测量各参数基本一致,ICC值为0.934 ～0.989,显示2次测量结果的一致性较好.RIS组胼胝体膝部、体前部、体后部的FA值分别为0.705±0.040、0.632±0.042、0.628±0.043,相比于正常对照组0.738±0.045、0.675±0.042、0.666±0.045,均显著减小,差异有统计学意义（t值分别为-3.526、4.487、-3.890,P值均＜0.01）；RIS组胼胝体压部、额叶和枕叶白质的FA值与正常对照组比较,差异均无统计学意义（t值分别为-1.387、-0.683、-1.243,P值均＞0.05）.RIS组胼胝体膝部、体前部、体后部的MD值分别为（0.891±0.038）、（0.839±0.047）、（0.833±0.039）×10-3 mm2/s,相比于正常对照组（0.874±0.035）、（0.794±0.031）、（0.792±0.057）×10-3 mm2/s,均显著增大,差异有统计学意义（t值分别为2.101、5.836、5.146,P值均＜0.01）；胼胝体压部、额叶白质和枕叶白质的MD值2组间比较差异均无统计学意义（t值分别为1.671、1.702、1.624,P值均＞0.05）.结论 应用DTI技术可检测到RIS患者的NAWM存在异常.

Objective To study whether abnormalities can be detected by MR diffusion tensor imaging （DTI） technology in radiologically isolated syndrome （RIS） patients with normal-appearing white matter （NAWM）.Methods Twenty-seven patients who met diagnostic criteria for RIS were collected.Sixteen age-and sex-matched healthy controls with normal neurologic examination findings and no history of neurologic or psychopathic disorders were included.All subjects were examined by both conventional scan and DTI scan on GE Signa 3.0 T MRI.All the images were transmitted to the Advantage Workstation 4.2P and postprocessed using functool software.Anisotropic maps and average diffusion coefficient （ADC） maps were reconstructed.Two ROIs were selected in the genu and splenium of the corpus callosum separately at the trigone of lateral ventricle level.Other 2 ROIs were selected in the anterior and posterior body of the corpus callosum separately at the level of the lateral ventricle body,and 1 ROI was selected in the white matter of bilateral frontal and occipital lobe separately,then the FA and MD values were measured.The diffusion indices （FA and MD）were analysed by SPSS 13.0.Independent-sample t test was performed to examine the group differences in each subregion.Intraclass correlation coefficient analysis was performed to assess the diffusion indices of two measurements in each subregion.Results The ICC of 2 measurements was 0.934-0.989 （P 〈 0.01）,which showed favorable consistency.The FA values were decreased obviously in the genu,anterior and posterior body of the corpus callosum of the RIS patients compared with controls （0.705 ±0.040 vs 0.738 ±0.045,0.632 ±0.043 vs 0.675 ±0.042,0.628 ±0.043 vs 0.666 ± 0.045,t =-3.526,-4.487,-3.890,P 〈0.01）,but the FA values of the two groups did not show any significant difference in the splenium,the white matter of the frontal and occipital lobe respectively （t =-1.387,-0.683,-1.243,P 〉0.05）.In comparison with controls,the RIS patients had increased MD values in the genu,anterior and posterior body of the corpus callosum.（0.891 ±0.038 vs 0.874 ±0.035,0.839 ± 0.047 vs 0.794 ± 0.031,0.833 ± 0.039 vs 0.792 ± 0.057,t =2.101,5.836,5.146,P 〈 0.05）,but the MD values of the two groups did not show any significant difference in the splenium,the white matter of the frontal and occipital lobe respectively （t =1.671,1.702,1.624,P 〉 0.05）.Conclusion The NAWM abnormalities in the patients with radiologically isolated syndrome could be detected by DTI.