重复时间和场强对脑白质弥散张量成像定量研究的影响  

Effects of repetition time and field strength on diffusion indices of brain white matter

作　　者：秦文[1] 李坤成[1] 于春水[1] 张帆[1] 

机构地区：[1]首都医科大学宣武医院放射科,北京100053

出　　处：《中国医学影像技术》2009年第7期1127-1130,共4页Chinese Journal of Medical Imaging Technology

基　　金：国家自然科学基金(30470519);北京市科技新星计划(2005B21)

摘　　要：目的研究重复时间(TR)以及场强对脑白质弥散张量成像(DTI)定量指标有无影响。方法分别利用1.5T和3.0TMR扫描仪对7只健康成年恒河猴进行DTI数据采集。在其他参数固定的情况下改变TR值(500～6000ms,共16个采样点),得到一系列DTI数据。选择双侧内囊后肢作为感兴趣区(ROI),并测量该ROI内的平均弥散率(MD),分数各向异性(FA)、纵向本征值(λ1)和横向本征值(λ2、3)。运用Pearson相关分析分析这些弥散指标与TR的线性关系,并采用双因素重复资料的方差分析比较两种场强下各指标均值是否有差异。结果当信噪比(SNR)足够大时(SNR>35),恒河猴白质区ROI各指标与TR无相关性(P>0.05)。与1.5T相比,3.0T的FA值较高,而MD及λ2、3较低(P<0.001)。两场强λ1差异无统计学意义(P>0.05)。结论场强可能影响DTI定量指标的测量,而TR时间对DTI定量的影响不显著。Objective To observe whether repetition time （TR） and field strengths have effects on diffusion indices of brain white matter. Methods Seven rhesuses underwent diffusion tensor MR imaging （DT-MRI） with a series of TRs （from 500 to 6000 ms） at 1.5T and 3.0T MR scanners, respectively. The mean diffusivity （MD）, fractional anisotropy （FA）, primary （λ1） and transverse eigenvalues （λ2,3） were measured in region of interest （ROD at the posterior limb of internal capsule. Pearson correlation analysis and two-way ANOVA were performed. Results None of the diffusion indices was correlated with TR （P〉0.05） when SNR was high enough （SNR〉35）. FA was significantly higher and the MD and λ2,3 were significantly lower at 3.0T than those at 1.5T （P〈0. 001）. No significant difference of λ1 was found between the two field strengths （P〉0. 05）. Conclusion Field strength may influence diffusion quantification, but not for TR, which should be considered in multi-center studies.

关 键 词：弥散张量成像 重复时间 场强 信噪比 

分 类 号：R445.2[医药卫生—影像医学与核医学] R-332[医药卫生—诊断学]