能谱联合迭代重建在重度肝硬化双低扫描中的应用价值

The application value of spectral scanning combined with iterative reconstruction in double-low technique scanning for severe liver cirrhosis

目的探讨能谱单能量成像联合前后置适应性统计迭代重建-V(ASIR-V)技术对重度肝硬化上腹部双低扫描的应用价值。方法前瞻性收集拟行上腹部增强扫描的肝硬化患者126例,按照随机数表法分为3组,每组42例。其中对照组采用120 kV、420 mg I/kg对比剂含碘量和FBP重建;能谱组和联合组均采用能谱扫描,300 mg I/kg,其中能谱组为60 keV单能量图像联合0前置和40%ASIR-V后置重建获得,联合组40%前置,并根据keV和后置比例,进一步分为2个亚组:50 keV联合50%ASIR-V后置和60 keV联合40%ASIR-V后置。图像客观指标及辐射剂量比较采用方差分析,图像主观指标比较采用秩和检验。结果除门脉期肝实质外,能谱组和联合组的CT值和CNR值较对照组差异有统计学意义(F=4.293 ~13.134 ,P<0.05),且两两比较,50 keV联合50%ASIR-V后置组高于对照组(q=1.825 ~3.736 ,P<0.05)。噪声和脏器总体图像质量评分差异无统计学意义,肝血管分支的显示50 keV联合50%ASIR-V后置组高于其余3组(Z=2.793 ~6.328,P<0.05)。联合组的辐射剂量低于能谱组、对照组(q=-4.879^-2.531,P<0.001 )。结论能谱单能量成像联合前后置ASIR-V技术在保证图像质量的前提下,对重度肝硬化患者上腹部增强扫描可降低对比剂量和辐射剂量。

Objective To investigate the clinical feasibility of spectral monochromatic imaging combined with adaptive statistical iterative reconstruction-V(ASIR-V)in upper abdominal enhanced scanning with double-low technique for severe liver cirrhosis. Methods Totally 126 cases performed abdominal contrast-enhanced CT scanning were collected prospectively and assigned to 3 groups with 42 cases in each group with random number table method . The filtered back projection algarithm, 120 kV and contrast agent dose of 420 mgI/kg were used for the cases of control group. The cases for spectral group and combined group were scanned with spectral imaging mode and contrast agent dose of 300 mgI/kg. The 60 keV monochromatic images combined with pre-0% and post-40% ASIR-V were selected and analyzed for spectral group. Combined group with pre-40% ASIR-V was divided into 2 subgroups with 50 keV, post-50% ASIR-V and 60 keV, post-40% ASIR-V separately. One-way ANOVA test was used for analysis of radiation dose and quantitative parameters, and Rank sum test was used for image subject evaluation. Results The CT numbers and CNR had significant differences among spectral group, combined group and control group(F=4.293 -13.134 , P<0.05) except for the images of liver parenchyma in PVP and that of 50 keV combined 50%ASIR-V group were higher than that of control group (q=1.825 -3.736 , P<0.05). No significant differences existed for image noise and overall image quality scores of organs in four groups. The visualization of hepatic vascular branches in 50 keV combined 50%ASIR-V group was higher than that of other three groups(Z=2.793 -6.328 , P<0.05). The radiation dose of combined group was lower than that of spectral and control group (q=-4.879--2.531, P<0.001 ). Conclusions Spectral monochromatic imaging combined with pre-and post-ASIR-V can reduce contrast agent dose and radiation dose without degrading image quality for the severe liver cirrhosis in upper abdominal enhanced scanning.