用酰胺质子转移磁共振成像技术评价鼠脑胶质瘤放疗疗效

发布时间：2018-01-31 06:26

本文关键词： 化学交换饱和转移成像 APT加权成像磁化转移率不对称性 NOE加权成像脑肿瘤 APT成像胶质瘤多参数MRI 放疗疗效评估　出处：《华中科技大学》2014年博士论文　论文类型：学位论文

【摘要】：目的：在4.7T动物MRI扫描仪上,定量分析胶质瘤动物模型在不同的射频饱和功率下酰胺质子转移(Amide Proton Transfer, APT)和核奥氏增强(Nuclear Overhauser Enhancement, NOE)效应,确定APT成像的最佳射频饱和功率。方法：用4.7T动物MRI扫描仪扫描8只9L胶质瘤模型大鼠,在不同的射频饱和功率下获得水共振频率两侧+/-6ppm范围内Z谱以及磁化转移率不对称性谱。再分别用9L、U87、GBM22胶质瘤模型来验证APT成像在该射频饱和功率下的成像效果。结果：在较低射频饱和功率(如0.6μT)下,在水共振频率右侧(-2.5到-5ppm,通常称为高场区)能够明显看到NOE信号,且对侧正常脑组织的NOE信号强度大于肿瘤组织。相反的,在水共振频率左侧的APT效应在相对高的射频饱和功率(1.3至2.1μT)达到最大,且肿瘤组织的APT效应大于对侧正常脑组织。磁化转移率不对称性分析显示,NOE效应降低了APT加权成像信号,但加强了肿瘤组织与对侧正常组织的APT加权成像信号对比度。在0.6至1.3μT射频饱和功率时,APT加权成像信号对比度达到最大。APT成像在1.3μT射频饱和功率下,在三种不同的胶质瘤模型中均能显示出良好的成像效果。结论：APT和NOE信号分别在不同的射频饱和功率下达到最大值。APT成像的理想射频饱和功率大约在1.3μT。目的：分析比较几种无创性的功能和分子MRI对胶质瘤放疗的疗效评价。方法：运用一自制小型动物放疗仪对14只U87胶质瘤模型裸鼠进行放疗(40或20Gy),另外6只胶质瘤模型裸鼠作为对照组。运用4.7T动物MRI扫描仪,分别在动物放疗前,放疗后3天、6天、9天和14天进行MRI扫描。定量分析肿瘤的MRI图像特征、肿瘤体积和动物的生存期。结果：常规MRI显示所有肿瘤在放疗后初期几天,体积仍然在逐渐增大。肿瘤的表观扩散系数(ADC)在(40或20Gy)放疗后(除了放疗后第3天外),均明显大于放疗前。肿瘤的血流量信号在放疗后所有时间点均明显低于放疗前,但是相对血流量信号(肿瘤组织血流量/对侧正常组织血流量)并未发生明显改变。与放疗前相比,APT加权信号在40Gy放疗后所有时间点均出现明显降低,而在20Gy放疗组中,只有放疗后第9天出现明显降低。血流图像与APT图像所显示的肿瘤特征与钆剂增强T1加权成像图相一致。结论：肿瘤的表观扩散系数,血流量信号和APT均可以用来预测胶质瘤的放疗疗效。在我们这个模型中,APT似乎更加有利于早期的疗效评估。
[Abstract]:Objective : To determine the optimal RF saturation power of APT imaging on a 4 . 7T animal MRI scanner . The optimal RF saturation power of APT imaging was determined by using 4 . 7T animal MRI scanner to scan 8 L glioma model rats . Results : Under lower radio frequency saturation power ( e.g . 0.6 渭T ) , NOE signal was observed at the right side of the resonant frequency ( - 2.5 to -5 ppm , commonly referred to as high field area ) , and the signal intensity of NOE in normal brain tissue was greater than that of tumor tissue . In contrast , the APT effect on the left side of water resonant frequency was greater than that of contralateral normal brain tissue . Conclusion : APT and NOE signals reach the maximum at different RF saturation power . The ideal RF saturation power of APT imaging is about 1.3 渭T . Objective : To evaluate the efficacy of several non - invasive functional and molecular MRI in the treatment of glioma . Methods : 14 U87 glioma model nude mice were treated with radiotherapy ( 40 or 20Gy ) and 6 glioma model nude mice as control group . Conclusion : The apparent diffusion coefficient , blood flow signal and APT of tumor can be used to predict the therapeutic effect of radiotherapy . In our model , APT appears to be more favorable for early treatment .

【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：R739.41;R445.2

【共引文献】