目的 对兔VX2移植瘤模型弥散加权成像(DWI)及LAVA动态增强扫描(DCE)的成像参数进行筛选和优化.方法 新西兰大耳白兔20只,制成VX2移植瘤模型,应用3.0 T MR对肿瘤进行DWI和DCE扫描.比较不同b值的对比噪声比(CNR)、信号强度比值(SIR)及表观扩散系数(ADC)比值的差异.比较LAVA成像中各后处理参数的图像质量,选择合适的参数.结果 b值取500、800、1 000 s·mm-2时,随着b值增加,肿瘤/瘤周CNR显著下降(F＝45.97,P＜0.01＝,肿瘤/瘤周(F＝12.02,P＜0.01＝、肿瘤周边/中心(F＝20.52,P＜0.01＝的SIR显著上升.尽管各部位的ADC值随b值的增加而下降,但肿瘤/瘤周(F＝0.845 6,P＞0.05)、肿瘤周边/中心(F＝2.744,P＞0.05)的ADC比值随着b值而上升.DCE中MSI和PEI图像对比度较清晰,肿瘤各部位和瘤周组织的参数差异显著,MTE和TP图像对比度差,参数无显著差异.结论 在进行兔VX2肿瘤的DWI成像时,选择h值为1 000 s·mm-2较为合适.在进行LAVA动态增强扫描时,宜选择MSI、PEI作为成像参数.%Objective To optimize imaging parameters of diffusion-weighted MR imaging (DWI) and dynamic contrast-enhanced MR imaging (DCE) (LAVA) for rabbit VX2 tumor models. Methods Twenty rabbit VX2 tumor models were enrolled in the study. DWI and DCE scan were performed with a 3.0 T MR scanner. CNR,SIR and ADC ratio with different b value were compared. Also,some parameters of LAVA enhanced images were compared and selected. Results When b values were 500,800, 1 000 s·mm-2 in DWl,there was an obvious decrease of CNR T-FI ( F =45.97, P ＜ 0.01 ) and an increase of SIRT-PT ( F =12.02, P ＜ 0.01 ) and SIRP/C ( F =20.52, P ＜ 0.01 ). The ADC ratio of tumor-peritumor (F =0.8456,P ＞ 0.05) and periphery-center (F =2.744,P ＞ 0.05) increased. In DCE,the difference of MSI and PEI were significant,and the image contrast was well. On the contrary,no significance was seen in MTE and PEl,and the derived images were undistinguishable. Conclusion For fMRI of rabbit VX2 tumor,b value of 1 000 s ·mm-2 is suitable in DWI. MSI and PEI should be selected in LAVA enhanced images.
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