降低时间分辨力对肝癌灌注及辐射剂量的影响

Effects of reducing temporal resolution on CT perfusion of hepatic carcinoma and radiation dose

目的探讨降低时间分辨力对肝癌灌注图像及参数的影响。方法采用第三代双源CT对20例原发性肝癌患者行上腹部灌注扫描,原始数据采样时间分辨力为1.5 s,将原始数据降低时间分辨力达3.0 s得到另一组数据。选择相同的ROI测量两组中肿瘤及肝硬化实质的灌注参数血流量(BF)、血容量(BV)、平均通过时间(MTT)、渗透性(FE)、肝动脉灌注量(ALP)、门静脉灌注量(PVP)、肝动脉灌注指数(HPI)。将两组图像质量及各灌注参数进行统计分析。结果降低时间分辨率至3.0 s时对灌注图像质量影响不大。肝癌BF、BV、ALP、HPI高于肝硬化实质,PVP低于肝硬化实质,差异具有统计学意义;肝癌FE、MTT高于肝硬化,但差异无统计学意义。时间分辨力为1.5 s、3.0 s的两组数据测得的肝癌和肝硬化实质的各灌注参数差异均无统计学意义。结论适当降低时间分辨力能获得满足诊断需要的图像质量及较准确的灌注参数值,且能有效地降低辐射剂量。

Objective To investigate the effects of reducing temporal resolution of CT perfusion(CTP)on the image quality and perfusion parameters of hepatic carcinoma.Methods Twenty patients with hepatic carcinoma were enrolled in this study and underwent an upper abdominal CTP with a third-generation dual source CT.Original data were acquired using temporal resolution of 1.5 s,and another data set was obtained by lowering temporal sampling rates to 3 s.According to the same mathematical model and ROI of the same part,perfusion parameters(BF,BV,MTT,FE,ALP,PVP and HPI)of tumor tissue and non-tumor tissue in each group were calculated respectively.Statistical analysis was performed to compare the image quality and perfusion parameters.Results Signal-noise ratio(SNR)and all perfusion parameters of 3 s temporal resolution data sets did not differ with that of the original data sets.The BF,BV,ALP,and HPI of tumor tissue were higher than non-tumor tissue,the PVP of tumor tissue was lower than non-tumor tissue(all P<0.05).The FE,MTT of tumor tissue were higher than non-tumor tissue(all P<0.05).Conclusion Properly decreasing temporal resolution on CTP can require accurate perfusion parameters and reduce the radiation dose effectively.