低千伏大螺距及迭代重建联合技术128层双源下肢静脉CTV的图像质量和辐射剂量研究

Image Quality and Radiation Dose of 128-Slice Dual-Source CT Venography Using Low Voltage Combined with High-Pitch Scanning and Hybrid Iterative Reconstruction

目的比较128层双源CT下肢静脉成像120 kVp标准螺距与100 kVp大螺距联合迭代重建两种扫描技术血管强化程度、图像质量及辐射剂量之间的差异。方法60例怀疑下肢深静脉血栓及静脉曲张患者分为两组:A组,30例患者,扫描方式为100 kVp,大螺距(3.2),迭代重建;B组,30例患者,120 kVp,标准螺距(1.0),滤过反投影法重建。比较两组下腔静脉、股静脉和腘静脉血管强化程度、图像噪声、图像质量评分和辐射剂量。结果下腔静脉、股静脉及腘静脉的血管强化程度两组之间具有统计学差异,A组比B组高。A组较B组图像噪声高,且有统计学意义。两组图像质量评分无统计学差异(P>0.05)。两组平均剂量长度乘积存在统计学差异[A组:(226.2±9.60)mGy·cm,B组:(797.2±96.8)mGy·cm,P<0.001]。结论低千伏、大螺距联合迭代重建双源CT下肢静脉成像技术可以获得满足诊断用图像,提高血管强化程度,并且大幅降低放射剂量。

Objective To compare the difference of vascular enhancement,image quality and radiation dose between 120 kVp standard pitch and 100 kVp large pitch combined iterative reconstruction of 128-slice dual-source CT venography of lower extremity.Methods A total of 60 patients with suspected deep venous thrombosis and varicose veins of lower limbs were divided into group A and group B,with 30 patients in each group.The scanning mode adopted by group A was 100 kVp with large pitch(3.2),and the reconstruction algorithm was iterative reconstruction.The scanning mode adopted by group B was 120 kVp,standard pitch(1.0),and the reconstruction algorithm was filtered back projection method.Then the enhancement degree,image noise,image quality score and radiation dose of inferior vena cava,femoral vein and popliteal vein were compared between the two groups.Results The vascular strengthening degree of inferior vena cava,femoral vein and popliteal vein in group A was higher than that in group B,and the difference between the two groups was statistically significant.The image noise of group A was higher than that of group B,and there was statistical significance.There was no significant difference in image quality score between the two groups(P>0.05).The mean dose length product of group A[(226.2±9.60)mGy?cm]was statistically different from group B[(797.2±96.8)mGy?cm](P<0.001).Conclusion Low voltage and large pitch combined with iterative reconstruction of dual source CT venography of lower extremity can obtain satisfactory diagnostic images,improve the degree of vascular enhancement,and significantly reduce the radiation dose.