80 kV结合前后置全模型实时迭代重建技术在腹部CT增强检查中的运用

Application of 80 kV combination of pre-and post-adaptive statistical iterative reconstruction-V in abdominal CT enhancement examination

目的:探讨80 kV管电压联合全模型实时迭代重建技术(adaptive statistical iterative reconstruction-V,ASiR-V)在腹部计算机断层扫描(computer tomography,CT)增强检查的最佳组合。方法:收集体质指数(body mass index,BMI)≤24.9 kg/m^(2)的正常或偏瘦患者进行腹部CT增强检查,随机分为常规组和低剂量组,每组40例。常规组120 kV管电压,采用前置0%ASiR-V进行扫描,扫描后分别采用滤波反投影重建(filtered back projection,FBP)和20%、40%、60%后置ASiR-V两种方式进行图像重建;低剂量组80 kV管电压,动脉期、门脉期和延迟期分别采用前置20%ASiR-V联合后置20%、40%、60%、80%ASiR-V,前置40%ASiR-V联合后置40%、60%、80%ASiR-V,前置60%ASiR-V联合后置60%、80%ASiR-V进行图像重建。对比2组图像CT值、对比噪声比(contrast to noise ratio,CNR)、图像噪声客观评分以及主观图像质量评分,并记录辐射剂量指标。结果:2组图像CT值差异有统计学意义(P<0.05)。2组图像低剂量组除A20、A40、V40、D60 CNR与常规组差异无统计学意义(P>0.05)外,其余低剂量组图像CNR值均高于常规组。2组图像噪声低剂量组除A60、V60、V80与常规组差异无统计学意义(P>0.05)外,其余低剂量组图像噪声均高于常规组。除后置80%ASiR-V重建图像质量差,其余图像主观评分均大于3分,满足诊断。低剂量组动脉期、门脉期、延迟期相比常规组有效剂量(effective dose,ED)分别下降66.81%、67.24%、70.61%。结论:对于BMI≤24.9 kg/m^(2)的正常或偏瘦患者,采用80 kV管电压结合前置40%叠加后置60%ASiR-V图像重建,能够在降低辐射剂量的条件下,获得满足影像诊断的图像,实现个体化扫描原则。

Objective:To explore the best combination of adaptive statistical iterative reconstruction-V(ASiR-V)for abdominal computer tomography(CT)enhancement under 80 kV tube voltage. Methods:The data of normal or thin patients with body mass index(BMI)≤24.9 kg/m^(2)who took enhanced abdominal CT examination were collected,and they were randomly divided into control group and low-dose group,each with 40 cases. The 120 kV tube voltage of the control group was scanned with the 0% pre-ASiR-V,and after the scanning,filtered back projection(FBP)and 20%,40% and 60% post-ASiR-V were used for image reconstruction. In the low-dose group,80 kV tube voltage,arterial phase,venous phase and delayed phase were respectively used with 20% pre-ASiR-V combined with 20%,40%,60% and 80% post-ASiR-V,40% pre-ASiR-V combined with 40%,60% and 80% post-ASiR-V and60% pre-ASiR-V combined with 60% and 80% post-ASiR-V for image reconstruction. The CT values,contrast to noise ratio(CNR),image noise objective score and subjective image parameters of the two sets of images were compared,and the radiation dose index was recorded. Results:There were statistically significant differences in CT values between the two groups of images(P<0.05). There was no statistically significant difference except for A20,A40,V40,D60 CNR between the low-dose group and the control group(P >0.05),and the CNR values of the remaining images of low-dose group were higher than those of the control group. There was no significant difference between the two groups of image noise except for A60,V60 and V80(P>0.05),and the image noise of the other low-dose groups was higher than that of the control group.Except for the 80% post-ASi R-V,the image quality was poor,and the subjective scores of the other two groups of images were all greater than 3 points,which meet the diagnosis. Compared with the control group,the effective dose(ED) of the low-dose group in the arterial phase,venous phase and delayed phase decreased by 66.81%,67.24% and 70.61%,respectively. Conclusion:For normal or thin patients patients with BMI ≤ 24.9 kg/m^(2),using 80k V tube voltage combined 40% pre-ASi R-V with 60% postASi R-V can obtain images meeting the needs of imaging diagnosis under the condition of reducing the radiation dose,and realize the principle of individualized scanning.