摘要
目的 通过改变一系列脉冲序列参数 ,以利于乳酸的最佳检测与定量分析。方法 制作含乳酸玻璃模型。改变一系列的MR脉冲序列参数 ,应用点解析频谱序列 (pointresolvedspectroscopy,PRESS)和激励回波序列 (stimulatedechoacquisition ,STEAM)获得乳酸模型的相应频谱。另外 ,对 12例脑病变患者和 2例健康志愿者进行磁共振频谱检查 ,测量出每个波峰的峰高 ,并绘出序列变化曲线图。结果 STEAM各波峰的峰向与PRESS序列一致 ,但STEAM各峰高均低于同等条件的PRESS峰。随着TE时间的延长 ,用乳酸模型测出的乳酸峰的峰高 序列曲线图呈波浪状变化 ,正向双峰在TE =2 6、2 70ms时共振波幅达到最大绝对值 ,负向双峰在TE =135～ 16 0ms之间达到最大绝对值。脑病变患者和健康志愿者的扫描结果表明 ,乳酸峰在优化的序列高于非优化的序列。
Objective To obtain the optimal detection and quantitative analysis of lactate by changing a series of parameters used in the MR pulse sequences.Methods A glass model containing lactate was utilized.The MR scanner was a 1.5 T system (Signa MR/i,GE).After using the fast gradient echo sequence to define the position of volume of interest (VOI),the spectra were obtained by using both PRESS and STEAM sequences.The experiment was also carried out in 12 patients with brain diseases and two volunteers.Three voxels (2 cm×2 cm×2 cm) were placed in external standard solution and the corresponding locations of the encephalopathy,respectively.The peak heights were measured after the baselines were corrected.The curves of the peak heights versus the TE were plotted using EXCEL program.Results The curves of lactate peaks versus TE obtained by the model using PRESS and STEAM sequences exhibited waveform characteristic.The up-doublets were recorded with their maximum peak heights using TE values of 26 ms and 270 ms,whereas the down-doublets were recorded at their peaks using a TE value between 135 to 160 ms.All the peaks recorded by STEAM sequence were similar to those recorded by PRESS sequence.However,the former were weaker than the latter.The results indicated that the optimized sequences were useful for better detection of lactate in clinical examinations.Conclusion The optimized sequences are able to benefit the detection and quantitative analysis of lactate.
出处
《中华放射学杂志》
CAS
CSCD
北大核心
2004年第10期1108-1111,共4页
Chinese Journal of Radiology
基金
国家自然科学基金资助项目 ( 3 0 170 2 62 /C0 10 5 11)
