脑磁共振扩散张量成像最佳扫描参数的优选

目的探讨脑磁共振扩散张量成像(DTI)的最佳扫描参数。方法对30例成年健康志愿者行脑DTI扫描,比较不同扫描参数[扩散敏感方向数(NDGD)、扩散敏感系数(b)值和层厚/层间距]对图像质量的影响。随机分为三组:NDGD组改变NDGD(6、15、25个),b值为1000 s/mm2,层厚/层间距为5/0 mm;b值组改变b值(500、1000、3000 s/mm2),15个NDGD,层厚/层间距为5/0 mm;层厚/层间距组改变层厚/层间距(8/2、5/0、3/0 mm),15个NDGD,b值为1000 s/mm2。由两名高年资放射科医师采用双盲法对图像质量进行评分并进行统计学分析。结果 25个NDGD时图像质量评分最高[(2.83±0.38)分],与15个NDGD[(2.67±0.51)分]和6个NDGD[(2.17±0.43)分]时比较,差异具有统计学意义(P<0.05)。b值为1000 s/mm2时图像质量评分最高[(2.67±0.49)分],与b值为500 s/mm2[(2.50±0.56)分]时比较,差异无统计学意义(P>0.05),与b值为3000 s/mm2[(2.06±0.55)分]时比较,差异有统计学意义(P<0.05)。层厚/层间距为8/2 mm和5/0 mm时图像质量评分较高,差异无统计学意义[(2.67±0.54)分vs(2.61±0.42)分,P>0.05],与3/0 mm[(1.94±0.35)分]时比较,差异有统计学意义(P<0.05)。结论 25个NDGD,b值为1000 s/mm2,层厚/层间距为5/0 mm时所获得的图像信噪比较高,脑灰、白质对比度较佳,有利于脑白质的细微结构研究,是脑DTI最佳扫描参数。

Optimization of the scanning parameter for MR diffusion tensor imaging of brain

Objective To investigate the optimal scanning parameters for diffusion tensor imaging （DTI） of the brain. Methods Thirty healthy adult volunteers were studied by DTI. Different parameters ineluding the numbers of the diffusion sensitive gradient direetions（NDGD）, b values, slic/interval thickness were evaluated. DTI were performed with different NDGD（6, 15and25）, b value（ 1000 s/lnm2）and slice/interval thiekness（5/O nlln）in group 1. DTI were performed with different b value（500, 1000 and 3000 s/mm2） ,NDGD（ 15）and slice/interval thickness （5/0 ram）in group 2. DTI were performed with different slice/interval thickness（8/2,5/0 and 3/0 mm）,NDGD（15）and b value（ 1000 s/mm2）in group 3. Two radiology experts gave a score to evm7 imaging with double blind methods,then compared the image quality. Results The quality of image with 25 NDGD was better than those with 15 NDGD（2.83± 0.38 vs 2.67±0.51 ,P〈0.05） and 6 NDGD （2.83±0.38 vs 2.17±0.43,P〈0.05）. The quality of image with b value of 1000 s/mm2 was equal to 500 s/mm2 （2.67±0.49 vs 2.50±0.56,P〉0.05） and better than 3000 shnm2 （2.67±0.49 vs 2.06±0.55,P〈0.05）.The quality of image with 8/2 mm of slice/interval thickness was equal to 5/0 mm（2.67±0.54 vs 2.61 ±0.42,P〉0.05） and better than 3/0 mm （2.67± 0.54 vs 1.94±0.35,P〈0.05）. Conclusions Scanning with 25 NDGD,b value of 1000 s/mm2 and 5/0 mm of siee/interval thickness is the best scanning parameter for MR diffusion tensor imaging of brain.