70 kV双球管模式下肢CT血管成像检查：与单源模式随机对照研究

A randomized controlled study of dual-source（70 kV） versus single-source （70 kV or 100 kV） CT angiography of the lower extremities

摘要:

目的：评估双源CT（dual-source CT，DSCT）双球管模式超低管电压（70 kV）下肢CTA检查的图像质量、辐射剂量。方法：收集90例腹主动脉及下肢动脉CTA的患者随机分为3组：A组：70 kV管电压，双球管模式，SAFIRE-3；B组：100 kV管电压，单球管模式，滤波反投影（filtered back projection，FBP）；C组：70 kV管电压，单球管模式，SAFIRE-3。测量腹主动脉、髂总动脉、股动脉、腘动脉的4个血管感兴趣区（region of interest，ROI）的CT值，信噪比（signal to noise ratio，SNR）和对比噪声比（contrast to noiseratio，CNR）及图像质量主观评分，并比较3组间辐射剂量。结果：①双球管70 kV组（A组）和单源70 kV组（C组）腹主动脉、髂总动脉、股动脉的3个血管ROI的CT值高于单源100 kV组（B组），双球管70 kV组SNR及CNR明显高于B、C组，差异有统计学意义（P<0.05）。②远端细小分支的显示双球管70 kV组（A组）明显优于B、C组，而B、C组间差异无统计学意义（P>0.05）。③3组CT剂量指数（CT dose index volume，CTDIvol）、剂量长度乘积（dose length product，DLP）差异均有统计学意义（P<0.05），B＞A＞C，双球管70 kV组（A组）较单源70 kV组（C组）辐射剂量升高约24%，但较单源100 kV组（B组）辐射剂量降低约18%。结论：大螺距双球管模超低管电压70 kV联合迭代重建技术下肢CTA检查，可降低辐射剂量，明显提高图像质量，并有利于远端细小血管分支的显示。

Abstract:

Objective：To evaluate the image quality and radiation dose of dual-source computed tomography at ultra-low tube voltage （70 kV）. Methods：A total of 90 patients undergoing CT angiography（CTA） of the abdominal aorta and lower extremity arteries were randomly divided into three groups：group A：70 kV，dual-source，and sinogram-affirmed iterative reconstruction（strength level 3）（SAFIRE-3）；group B：100 kV，single-source，and filtered back projection；group C：70 kV，single-source，and SAFIRE-3. Then，the CT values，signal-to-noise ratio（SNR），and contrast-to-noise ratio（CNR） of four vascular regions of interest （ROIs） of the abdominal aorta，the common iliac artery，the femoral artery，and the radial artery were measured，image quality was subjectively scored，and the radiation dose was compared between the three groups. Results：Groups A and C had significantly higher CT values of three ROIs of the abdominal aorta，the common iliac artery，and the femoral artery than group B，and group A had significantly higher SNR and CNR of the three vascular ROIs than groups B and C（P<0.05）. The image quality of the distal small vascular branches was signif－icantly higher in group A than that in groups B and C（P<0.05），but there was no significant difference between group B and group C（P>0.05）. The volume CT dose index volume and dose-length product were significantly different between the three groups（P<0.05），and the values were highest in group B and lowest in group C. The radiation dose in group A was 24% higher than that in group C but 18% lower than that in group B. Conclusion：High-pitch dual-source CTA of the lower extremities at ultra-low tube voltage（70 kV） combined with iterative reconstruction tech－nique can reduce radiation dose，increase the image quality，and contribute to the imaging of distal small vascular branches.