双源CT大螺距前瞻扫描在胸痛三联症成像中的应用

Dual Source CT High Pitch Prospective Scan in Triple-rule-out Acute Chest Pain Examination

目的探讨双源CT大螺距前瞻扫描在胸痛三联症排查中的成像质量及受心率变化的影响。资料与方法从拟行胸痛三联检查的患者中连续选取32例,采用随机数字表法分为研究组和对照组,对照组16例采用64排回顾式螺旋扫描,研究组16例采用双源大螺距前瞻扫描,比较两组主动脉及肺动脉CT值、噪声、信噪比(SNR)、对比噪声比(CNR)、辐射剂量,并对冠状动脉图像进行主观评分。结果两组主动脉及肺动脉CT值、噪声、SNR、CNR差异均无统计学意义(P>0.05),但研究组冠状动脉评分优秀率(85.5%)低于对照组(93.9%)(χ2=8.33,P<0.05)。考虑受心率波动过大的影响,排除对照组5例和研究组4例心率波动>5次/min的患者后,重新比较两组图像冠状动脉主观评分,差异无统计学意义(χ2=0.12,P>0.05)。对照组辐射剂量为(20.8±6.2)m Sv,明显高于研究组的(2.3±0.4)m Sv(t=17.142,P<0.01)。结论应用双源螺旋CT大螺距前瞻扫描行胸痛三联排查,对于心率<80次/min且波动<5次/min的患者成功率高,图像质量与回顾性扫描无显著差异,但辐射剂量减少,仅为(2.3±0.4)m Sv,具有潜在的应用和推广价值。

PurposeTo investigate the image quality of Dual Source CT （DSCT） high pitch prospective scan in acute chest pain examination by using ＂triple-rule-out＂ （TRO） protocol and its responses to heart beat rate change.Materials and Methods Thirty-two consecutive patients who planned to undergo TRO acute chest pain examination were enrolled and randomly divided into research group and control group. The conventional retrospective spiral scanning protocol was applied to the patients in the control group, while the high pitch prospective spiral scanning mode was used in the research group. CT value, noise level, SNR, CNR and radiation dosage in aorta and pulmonary arteries were recorded and compared between the two groups, and the image quality of the coronary arteries was scored subjectively.Results No significant difference was found in the aspects such as CT value, noise level, SNR, CNR radiation dosage in aorta and pulmonary arteries （P〉0.05）; however, the subjective scoring for coronary artery in the research group （85.5%） was significantly lower than that in the control group （93.9%） （χ^2=8.33,P〈0.05）. Considering the influence of severe heart rate changes, we excluded those patients whose heart rate variance was more than 5 beats/min （control group：n=5; research group：n=4） and then compared the image quality of the two groups again. The subsequent results showed no difference （χ^2=0.12,P〉0.05）. In addition, the radiation dosage in the control group was significantly higher than that in the research group [（20.8±6.2） mSvvs. （2.3±0.4） mSv;t=17.142,P〈0.01].Conclusion DSCT high pitch prospective scanning in TRO protocol shows high success rate in examining patients with acute chest pain whose heart beat rate is lower than 80 beats/min and heart beat variance is less than 5 beats/min. The image quality has no difference with that derived from retrospective scan but with far more less radiation dose （2.3±0.4） mSv. This method thus is promising and can be widely promoted clinically.