Abstract: Objective To evaluate the feasibility of low-radiation-dose and low-contrast-dose （double low-dose） scanning during the pulmonary artery phase and thoracic aorta phase（dual-phase） in acute myocardial infarction, pulmonary embolism and aortic dissection （triad of chest pain） by spiral CT. Methods 156 patients collected from Sun Yat-sen Memorial Hospital were included in our study. And they were divided into two groups. The observation group consisted of 39 patients with acute chest pain, and 117 ordinary patients composed the control group. Patients of observation group received double low-dose CT scanning of dual phase （pulmonary artery phase and thoracic aorta phase）, including CT pulmonary angiography （CTPA） （CTPA1 group）, coronary artery CT angiography （CCTA） （CCTA1 group） and thoracic aorta CT angiography （TCTA） （TCTA1 group）. And the three kinds of images were acquired at one scanning. According to the needs of different imaging sites, patients of control group were again divided three groups, including CTPA2 group （n=39）, CCTA2 group （n=39） and TCTA2 group （n=39）. And the images were acquired in a routine scanning mode. All of the images were reconstructed and analyzed by two radiologists. Qualitative evaluation of image quality was made.The dose length product （DLP） and average volume CT dose index （CTDI） were recorded, and the effective radiation dose was calculated accordingly. CT value and SD value of the center point of each trunk vessel cavity were measured to calculate and compare the noise ratio （CNR）. Results The K values of the scores of pulmonary artery, coronary artery and thoracic aorta between observation and control group were 0.60, 0.68 and 0.61, respectively, indicating good consistency. There were no statistical differences in CNR and average CT value between observation and control groups （P>0.05）. No significant differences existed in the effective radiation dose of CCTA between two groups （P>0.05）. However,the effective radiation dose of CTPA and TCTA in observation group was significantly lower than that in control group （P<0.05）. Conclusion The double-low-dose spiral CT scanning of dual phase has lower effective radiation dose and its image quality meets the clinical requirements.

Key words: angiography, myocardial infarction, aortic dissection, pulmonary embolism, double-low-dose spiral CT scanning of dual phase

摘要： 目的 探讨双低剂量肺动脉期与胸主动脉期螺旋CT双期扫描在胸痛三联征的可行性研究。方法 将收集于中山大学孙逸仙纪念医院的156例患者分为2组,观察组（39例）为急性胸痛患者,行双低剂量肺动脉期与胸主动脉期螺旋CT双期扫描,包括肺动脉CT血管造影（CTPA）（CTPA1组）、心脏冠状动脉CT血管造影（CCTA）（CCTA1组）和胸主动脉CT血管造影（TCTA）（TCTA1组）一次成像。常规组（117例）分别实施CTPA（CTPA2组,39例）、CCTA（CCTA2组,39例）和TCTA（TCTA2组,39例）。所有图像分别由两位医师重建并对其进行分级评分,分别记录、分析和比较两组图像质量、CT值、图像对比噪声比（CNR）和有效辐射剂量。结果 观察组肺动脉、心脏冠状动脉及胸主动脉与常规组的对应血管评分,K值分别为0.60、0.68和0.61,其一致性好。观察组与常规组对应血管图像的CNR及平均CT值均没有统计学差异（P>0.05）。观察组的有效辐射剂量与常规组中CCTA2组没有统计学差异（P>0.05）;观察组有效辐射剂量分别与常规组中CTPA2组及TCTA2组有统计学差异（P<0.05）,且常规组两组均高于观察组。结论 双低剂量螺旋CT双期扫描的图像质量满足临床需求且有效辐射剂量较低。

关键词: 胸痛三联征, 心肌梗死, 主动脉夹层动脉瘤, 肺动脉栓塞, 螺旋CT双期扫描