兔肝VX2瘤活体二维多体素 1H-MRS成像STEAM和PRESS序列的比较

目的 探讨不同的定位序列对兔肝VX2瘤活体二维多体素1H-MRS(2D 1H-MRS)成像的影响. 材料与方法 兔肝VX2瘤荷瘤兔14只,于第一期(种植后第2～3周)和第二期(种植后第4周)利用1.5T磁共振扫描仪行常规MRI,并在其他参数不变的条件下分别采用激励回波采样(STEAM)和点解析波谱(PRESS)序列行活体2D 1H-MRS检查,观察不同序列波谱图的基线情况,测量主要代谢物波峰的信噪比、中心位置、半高宽和峰下积分面积比值,并进行统计学分析. 结果 (1)STEAM和PRESS序列各行25瘤次2D 1H-MRS采集,其中第一期成功率为78.6%,第二期成功率为100%,总体技术成功率为88.0%.(2)在相同时期、相同部位,不同序列所得波谱图在基线情况、代谢物波峰的信噪比、中心位置、半高宽及各个代谢物峰下积分面积的比值(包括谷氨酸胺和谷氨酸复合物(Glx)/脂质(Lip)、胆碱化合物(Cho)/Lip和糖原和葡萄糖复合物(Glyu)/Lip)差异无统计学意义(P>0.05). 结论 利用1.5T磁共振扫描仪行兔肝VX2瘤活体2D 1H-MRS检查可成功获得可析性波谱,技术成功率为88.0%.其他扫描条件和参数相同时,采用短TE(30 ms),STEAM和PRESS序列在波谱质量和检测肝内主要代谢物的敏感性方面无明显差异.

Comparison of STEAM and PRESS in vivo Two Dimension Multi voxel 1H Magnetic Resonance Spectroscopy for Rabbit Liver VX2 Tumor

Objective To evaluate the effect of sequences in vivo 2D 1H MRS for rabbit liver VX2 tumor. Materials and Methods 2D 1H MRS acquisitions, including STEAM and PRESS sequences, were performed in vivo for 14 rabbits with liver VX2 tumors at two stages respectively at 1.5 T MRI scanner. The first stage was on 2nd or 3rd week and the second stage was on 4th week after VX2 tumor was implanted. The distinctions between two sequences were analyzed with the baseline, SNR, location of peak, FWHM of peak and the relative metabolite to lipid ratios. Results (1) The entire tests were finished in 25 tumors of 14 rabbits. Of all the spectra, 88% (22/25) could be analyzed successfully, 78.6%(11/14) in the first stage and 100%(11/11) in the second stage.(2) At the same stage and the same part of the tumor, The baseline, SNR, location and FWHM of metabolites peaks were similar in different sequences (P>0.05) .The distinction of the relative metabolite to lipid ratios between STEAM and PRESS, including Glx/Lip, Cho/Lip and Glyu/Lip ratios was no significant (P>0.05). Conclusion 2D 1H MRS of rabbit liver VX2 tumor in vivo could be performed by the 1.5 T MR scanner and its total technique successful rate is 88.0%. STEAM and PRESS with short TE (30 ms) are well consistent with each other when other parameters are the same.