3.0 T MRI化学交换饱和位移成像对心肌肌酸代谢可行性的实验研究

摘要

目的 探讨3.0 T MRI化学交换饱和位移(CEST)成像在体外模型中对心肌肌酸代谢的可行性.方法 采用德国Siemens 3.0 T MR成像仪对含有不同浓度(分别为10、20、30、40、50 mmol/L)肌酸的体外模型进行心肌肌酸CEST成像技术(CrEST).分别采用基础CrEST、非心电门控CrEST和心电门控CrEST序列.测量3种序列获得图像的信噪比(SNR),观察磁化转移率(MTR)图谱.采用单因素方差分析比较各序列肌酸图像SNR的差异,非心电门控CrEST、心电门控CrEST序列所获MTR与基础序列MTR的相关性采用Pearson相关分析完成.结果 采用3个CrSET序列均成功完成了肌酸体模成像,获得满足临床诊断的CrEST原始图像.不同序列不同浓度肌酸的伪彩色编码CrEST图显示不同浓度肌酸间信号差异明显,随着肌酸浓度增加,CrEST效应增强.基础CrEST、非心电门控CrEST和心电门控CrEST序列肌酸图像的SNR分别为47.6±7.1、58.5±3.7和65.0±1.6,差异有统计学意义(P<0.05),其中非心电门控序列CrEST、心电门控CrEST序列SNR高于基础CrEST序列,差异有统计学意义(P值分别为0.026、0.001),而非心电门控序列CrEST、心电门控CrEST序列间的SNR差异无统计学意义(P>0.05).非心电门控CrEST序列和心电门控CrEST序列获得的MTR与基础序列MTR均具有明显正相关(r2值分别为0.974、0.997,P均<0.05).结论 与基础CrEST序列相比,优化后的心电门控CrEST序列可获得较高SNR的CrEST图像,临床评价心肌肌酸代谢可行.%Objective To investigate the feasibility of chemical exchange saturation transfer (CEST) imaging in the measurement of myocardial creatine (Cr) metabolites in phantom model using 3.0 T MR. Methods Five phantoms were made according to the volume percentage of Cr ranging from 10 to 50 mmol/L with an interval of 10 mmol/L. 3.0 T MR examinations with base protocol sequence,sequence with and without ECG were performed. Signal to noise,CrEST effect and Z spectra were analyzed. Comparison of signal noise ratio (SNR) among the three methods was performed using an analysis of variance. Bivariate correlations were obtained through Pearson analysis. Results Phantom studies demonstrated that different concentrations of Cr exhibited significant CEST effect with the three sequences. The SNR obtained by sequences with and without ECG were both higher than that of base sequence (both P<0.05). Moreover,no significance of SNR was found between sequences with and without ECG (P>0.05). There were positive correlation of MTR between sequences with ECG,sequences without ECG and base protocol sequence (r2= 0.974 and 0.997, both P<0.05). Conclusion Compared with base protocol sequence, the optimized sequence with ECG can acquire higher SNR CrEST images,indicating that myocardial CrEST imaging could be performed in clinical practice.