不同屏气方式对冠状动脉CT血管成像辐射剂量和图像质量的影响

目的 观察不同屏气方式对冠状动脉CT血管成像（CCTA）辐射剂量和图像质量的影响。方法 将150例疑诊冠心病患者随机分为3组（每组50例），对A组于深吸气末屏气、B组于平静呼吸下屏气、C组于深呼气末屏气下行CCTA检查；记录扫描前平静呼吸时心率（基础心率）、扫描时屏气心率及容积扫描长度，比较各组辐射剂量和图像质量差异。结果 147例顺利完成检查，3例C组患者因图像模糊、无法评价而被排除。3组患者扫描时屏气心率均明显低于基础心率（P均<0.01）。B、C组容积扫描长度、剂量长度乘积（DLP）及有效剂量（ED）均低于A组（P均<0.05），B、C组间差异均无统计学意义（P均>0.05）。A组共评估698个冠状动脉节段，其中4分678个，3分20个；B组共评估696个冠状动脉节段，其中4分682个，3分14个；C组共评估656个冠状动脉节段，其中4分615个，3分41个；3组图像质量评分差异无统计学意义（P>0.05）。结论 于平静呼吸屏气下行CCTA可在保证图像质量的同时降低容积扫描长度及辐射剂量。

Impact of different breath holding methods on radiation dose and image quality of coronary artery CT angiography

Objective To observe the impact of different breath holding methods on radiation dose and image quality of coronary artery CT angiography (CCTA). Methods Totally 150 patients with suspected coronary heart disease who underwent CCTA were randomly divided into group A (holding breath at the end of deep inspiration), B (holding breath under calm breath) and C (holding breath at the end of deep breath out) (each n=50). The heart rate under quiet breath before scanning (basic heart rate), the heart rate under breath holding during scanning and volume scanning length were recorded, and the radiation dose and image quality were compared among groups. Results Totally 147 patients completed the examination successfully, whereas 3 cases of group C were excluded for blurred image unable to be evaluated. The heart rates during breath holding were lower than basic heart rate of patients in all 3 groups (all P<0.01). The volume scan length, dose-length product (DLP) and effective dose (ED) in group B and C were significantly lower than those in group A (all P<0.05), while there was no significant difference between group B and C (all P>0.05). There were 698 coronary segments evaluated in group A, 678 sored 4 and 20 scored 3; 696 segments in group B, 682 scored 4 and 14 scored 3, 656 segments in group C, 615 scored 4 and 41 scored 3. No significant difference of image quality scores was found among groups (P>0.05). Conclusion CCTA performed during breath holding under calm breath could not only ensure imaging quality but also reduce the volume scanning length and radiation dose.