1.5T磁共振化学交换饱和转移成像的影响因素分析

发布时间：2018-06-07 05:04

本文选题：磁共振成像(MRI) + 化学交换饱和转移(CEST)　；参考：《波谱学杂志》2017年03期

【摘要】：本文探讨1.5 T磁共振化学交换饱和转移(Chemical Exchange Saturation Transfer,CEST)成像的影响因素.通过试管模型和临床病例,采用GE Signa HDe 1.5 T磁共振成像(Magnetic Resonance Imaging,MRI)扫描仪分别进行不同矩阵、激励次数、翻转角、磁化传递翻转角的CEST成像对比分析,以及不同激励次数、磁化传递翻转角的Z谱分析,并从成像组织、成像设备、成像技术等方面对原始图信号、酰胺质子转移(Amide Proton Transfer,APT)信号及Z谱进行分析研究.实验结果表明1.5 T MRI扫描仪的CEST图像信噪比相对较低,且磁场稳定性及均匀度影响了CEST成像的效果.在其他参数不变的情况下,降低采集矩阵和增加激励次数与翻转角可以增加原始图像信噪比.磁化传递翻转角为105?时,CEST成像效果最好.激励次数为2、磁化传递翻转角为105?时,所得数据符合组织Z谱情况.模型Z谱在磁化传递频率为-294~-194 Hz范围可显示30%谷氨酸(Glu)、碘剂(I_(320))、纯水(H_2O)、肌酸(Cr)的信号差异,与H_2O差异最大处在-244~-214 Hz.原始图像信号30%I320明显高于Glu、H_2O、Cr,Cr略低于Glu,APT图Cr略低于Glu.25例脑肿瘤的APT图呈高信号、12例脑梗塞的APT图呈低信号,CEST原始图像均可区分病变区域.有12例因采集时间、患者配合情况、环境及室温等影响导致CEST成像的失败.由此得出1.5 T场强下,CEST技术受到成像组织、设备、技术等因素的影响,需要进行多方面优化.在保证磁场稳定性及均匀度的情况下,优化参数的CEST成像和Z谱成像可以区分代谢物及其浓度.
[Abstract]:In this paper, we discuss the influencing factors of 1.5 T magnetic resonance chemical exchange saturation transfer (CTT) chemical Exchange Saturation transfer (CEST) imaging. In vitro model and clinical case, CEST imaging of different matrices, excitation times, flipping angle, magnetization transfer flip angle, and different excitation times were performed by GE Signa HDe 1.5T magnetic Resonance imaging scanner. The Z-spectrum analysis of magnetization transfer inversion angle, and the analysis and study of the original image signal, amide proton transfer Proton transfer signal and Z spectrum from the aspects of imaging tissue, imaging equipment, imaging technology and so on. The experimental results show that the signal-to-noise ratio of CEST images is relatively low in 1.5T MRI scanner, and the stability and uniformity of magnetic field affect the effect of CEST imaging. The SNR of the original image can be increased by decreasing the acquisition matrix and increasing the frequency of excitation and the turning angle under the condition of invariant other parameters. The magnetization transfer flip angle is 105? The effect of CEST imaging is the best. The frequency of excitation is 2 and the angle of magnetization transfer is 105? The obtained data accord with the Z spectrum of tissue. The model Z spectrum in the magnetization transfer frequency range of -294 ~ 194 Hz can show the signal difference of 30% glutamate Glun, iodide I _ (320), pure water H _ 2O _ (2), creatine (Cr), and the biggest difference is in -244 ~ (4) ~ (-214) H _ (2) H _ (2) H _ (2). The 30%I320 of the original image was significantly higher than that of the Glu-H2O-Cr, which was slightly lower than that of the Gluapt-Cr, which was slightly lower than that of the APT of the Glu.25 patients with brain tumors. The original images of 12 cases of cerebral infarction showed that the original images of 12 cases of cerebral infarction showed low signal intensity and the original images could distinguish the lesion area. CEST imaging failed in 12 cases due to the influence of acquisition time, patient coordination, environment and room temperature. It is concluded that the CEST technology under 1.5 T field strength is affected by imaging organization, equipment, technology and so on, and needs to be optimized in many aspects. Under the condition of the stability and uniformity of magnetic field, the optimal parameters of CEST imaging and Z spectrum imaging can distinguish metabolites and their concentrations.
【作者单位】：厦门医学院附属医院厦门市第二医院医学影像科;厦门大学电子科学系福建省等离子体与磁共振研究重点实验室;
【基金】：厦门市科技局科技惠民计划资助项目(3502Z20144052) 卫生部福建省卫生教育联合攻关计划资助项目(WKJ-FJ-05)
【分类号】：R445.2

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