自适应性统计迭代重建技术结合低管电压在肝脏三期增强低剂量扫描中的应用

Application of adaptie statistical iterative reconstruction technology combined with low tube voltage in three phase enhanced low dose liver scanning

目的探讨自适应性统计迭代重建(ASIR)技术结合低管电压在肝脏三期增强低剂量扫描中的应用价值。方法随机数字表法选取2017年3至11月哈尔滨医科大学附属第二医院CT诊断科动脉期、延迟期和门脉期扫描方式的不同患者两组各50例行GEDiscovery CT 750 HD肝脏CT三期增强扫描,其中男56例、女44例,年龄27~73岁,42例患者患有肝细胞癌,44例患者患有肝血管瘤,14例患者为其他疾病。A组患者动脉期和延迟期采用低剂量扫描即100kV+ASIR,门静脉期采用常规剂量扫描即120kV+滤过反投影(FBP);B组患者动脉期和延迟期采用常规剂量扫描即120kV+FBP,门静脉期采用低剂量扫描即100kV+ASIR;同时对所有低剂量扫描期相采用FBP重建,得到常规重建模式下的低剂量图像。图像质量客观评价指标部分采用完全随机设计方差分析进行,并在此基础上采用Dunnett-t检验进行组间两两比较;对于主观评价部分,采用多组比较的秩和检验。结果ASIR技术结合低管电压在肝脏三期增强低剂量扫描,低剂量组较常规剂量组辐射剂量降低37%;图像质量主观评价低剂量组(100kV+ASIR)与常规剂量组(120kV+FBP)差异无统计学意义(P>0.05);图像质量客观评价除低剂量组(100kV+ASIR)门静脉期噪声略差于常规剂量组(120kV+FBP)外(低剂量10.86±1.98,常规剂量9.40±2.12,P<0.05),其余各期各评价指标均优于或无差别于常规剂量组。结论使用ASIR技术结合低管电压可用于肝脏三期增强低剂量扫描,且图像质量有一定的提升。

Objective To explore the application value of adaptive statistical iterative reconstruction (ASIR) combined with low tube voltage in three-stage enhanced low-dose scan of liver. Methods From March 2017 to November 2017, two groups which each group included 50 patients were randomly selected at the Second Affiliated Hospital of Harbin Medical University with different stages of arterial phase, delayed phase and portal vein scanning. GE Discovery CT 750 HD Liver CT Ⅲ was used during enhanced scanning. A total of 100 patients included 56 males and 44 females, aged 27-73 years old and 42 patients with hepatocellular carcinoma, 44 patients with hepatic hemangioma, and 14 patients with other diseases. The arterial and delayed period of group A patients were scanned with a low dose of 100 kV+ASIR, and the portal vein phase was conventional. Dosage scanning was 120 kV+FPP;the arterial and delayed period of group B was normal dose scanning, 120 kV+FPP, and the portal vein phase was low dose scanning, 100 kV+ASIR. At the same time, FBP reconstruction was used for all low-dose scanning phases to obtain low-dose images under normal reconstruction mode. The objective evaluation index of image quality was analyzed by completely randomized design analysis of variance, and Dunnett-t test was used to compare the two groups. For the subjective evaluation part, the rank sum test of multiple groups was used. Results ASIR combined with low tube voltage enhanced low dose scanning in the third phase of the liver, and the radiation dose decreased by 37% in the low dose group compared with the normal dose group. There was no statistically significant difference between the low dose group (100 kV+ASIR) and the normal dose group (120 kV+FPP) in subjective image quality evaluation (P>0.05);objective evaluation of image quality except for low dose(100 kV+ASIR) portal stage noise slightly worse than conventional dose group (120 kV+FBP) (low dose 10.86±1.98, conventional dose 9.40±2.12, P<0.05), the other indexes in each period were superior or indifferent to the normal dose group. Conclusion ASIR technique combined with low tube voltage can be used in the third phase of liver enhanced low-dose scanning and the image quality is improved.