自适应迭代重建在双低剂量CTU排泄期中的应用

Application of Adaptive Statistical Iterative Reconstruction in the Excretion Phase of CT Urography with Double Low Dose Scan

目的探讨使用双低剂量(低辐射剂量和低对比剂总量)并运用自适应迭代重建(Adaptive Statistical Iterative Reconstruction,ASIR)算法重建图像,进行泌尿系CTU检查的可行性。方法 60例有泌尿系疾病拟行CTU扫描的患者随机分为A、B两组,各30例。A组为常规剂量组,管电压120 k V,滤波反投影(Filtered Back Projection,FBP)重建。B组为低剂量组,管电压为80 k V,噪声指数为15,ASIR重建图像。测量并计算A、B两组图像噪声、对比噪声比(CNR)、容积加权CT剂量指数(CTDIvol)、有效剂量(ED),并由3位放射诊断医师对图像进行评分。结果 A、B两组图像质量主观评分为(4.56±0.45)和(3.78±0.56),CNR为(27.82±15.55)和(22.13±13.46),差异均无统计学意义(P>0.05)。B组的CTDI比A组降低了55.26%,ED比A组降低了56.82%,对比剂总量比A组减少23.48%,差异均有统计学意义(P<0.05)。结论CTU检查使用双低剂量并运用ASIR方法重建图像,能够在保证图像质量的前提下有效地降低辐射剂量,减少对比剂的不良反应。

Objective To evaluate the feasibility of CT urography(CTU)scanned with double low-dose(low-dose contrast agent and low-dose radiation),which combined with adaptive statistical iterative reconstruction(ASIR).Methods A total of60patients underwent CTU were randomly divided into group A and B,with30cases in each group.Patients in group A received a conventional scan with120kV and filtered back projection(FBP)reconstruction.Patients in group B received a low-dose scan with80kV,with noise index of15,and image reconstruction by ASIR.The image noise,contrast noise ratio(CNR),volume weighted CT dose index(CTDIvol)and effective dose(ED)were measured and calculated.Image quality was evaluated by3radiologists.Results The image quality score of group A and B were4.56±0.45and3.78±0.56,respectively;CNR were27.82±15.55and22.13±13.46,respectively.There were no significant difference between group A and B(P>0.05).CTDI of group B was much lower than that in group A,ED of group B was much lower than that of group A.The contrast medium volume of group B was lower than group A.There were significant difference between group A and B(P<0.05).Conclusion In CTU examination,scanning with double low-dose and combining ASIR can reduce the radiation dose and incidence of contrast medium adverse reaction with maintained image quality.