中文摘要：

目的 评估高级迭代重建算法（advanced iterative reconstruction，AIR）在低剂量冠状动脉CT成像中的应用价值。方法对临床拟诊断为冠心病的100例患者使用256层螺旋CT行回顾性后门控技术冠状动脉成像，40例使用常规剂量（120kV，800mAs）；60例任保证管电压不变的情况下降低管电流，同时采用高级迭代重建算法（iDose）和滤过反投影重建法（filter back projection，FBP）进行后处理，其中30例采用600mAs，30例采用400mAs。将400mAs＋FBP，600mAs＋FBP，800mAs＋FBP，400mAs＋iDose，600mAs＋iDose分别标记为A-E组。图像质量、噪声、容积CT剂量指数（CTDIvol）和有效剂量（ED）测量记录用于图像评价。结果A-E组图像评分分别1．72±0．52，1．53±0．51，1．50±0．31，1．63±0．48，1.43±0.41分，400mAs、600mAs及800mAs使用FBP图像无明显差别（P〉0．05）；同时400mAs、600mAs应用AIR与800mAs应用FBP的图像质量无明显差别。信噪比（SNR）分别为13．79±4．63，15．83±4．30，17．86±6．13，17．83±6．16，20．07±5．04；对比噪声比（CNR）分别为14．04±5．25，16．56±4．85．18．46±5．86。18．27±6．69，19．46±6．09；同时使用FBP重建，400mAs的CNR明显低于600mAs和800mAs组的CNR，400mAs发600mAs使用iDose重建后图像的CNR与800mAs使用FBP组的CNR相当；在400mAs及600mAs剂量下使用AIR均较FBP图像的CNR提高。400mAs、600mAs、800mAs的ED分别为（5．07±0．40）mSv、（7．59±0．65）mSv和（9．64±o．97）mgv，其中使用400mAs和600mAs有效辐射剂量较800mAs分别降低了47％和21％（P〈0．05）。结论使用高级迭代重建算法可以降低图像噪声及增加图像对比信噪比，从而进一步提高了降低辐射剂量的潜能。

英文摘要：

Objective To evaluate the value of cardiac computed tornography angiography using low-dose with advanced iterative reconstruction（iDose）. Methods 100 consecutive patients who underwent cardiac CT scans were divided into three groups. Conven- tional close（ 120 kV,800 mAs）was implied into 40 cases as group A,both iDose and filter back projection（ FBP） were used in the residual 60 cases under the condition of remaining the tube voltage and decreasing the tube current,including 600 rnAs was used in 30 cases as group B and 400 rnAs was used in 30 cases as group C. 400 mAs plus FBP,600 rnAs plus FBP,800 rnAs plus FBP,400 rnAs plus iDose, 600 m As plus iDose were marked as A to E groups. Image quality, noise, volume CT dose index （CTDIvol）, and effective dose （ED） were measured. Results In group A-E,the image scores were 1. 72±0. 52,1. 53±0. 51,1. 50±0. 31,1. 63±0. 48,1. 43±0.41 ,the contrast to noise ratio（CNR） were 14.04±5.25,16.56±4.85,18.46±5.86,18.27±4.6.69,19.46±6.09,the signal to noise ratio（SNR） were 13.79±4.63,15.83±4.30,17.86±6.13,17.83±6. 16,20.07±5.04 respectively,using FBP, 400 mAs had lower CNR or SNR compared to 600 mAs and 800 mAs（P〈0.05） ,while there was no significant difference between 400 rnAs and 600 mAs using iDose and 800 rnAs using FBP in CNR and SNR （P〉0.05）. The image score had no significant difference among 400 mAs,600 mAs and 800 mAs using FBP or iDose. The effective doses of 400 mAs , 600 mAs and 800 mAs were（5.07±0.40）mSv, （7.59±0.65）mSv and（ 9.64±0.97 ）mSv respectively , the effective dose of 400 mAs was reduced by 47% （ P〈0.05 ）. Conclusion Using AIR can reduce image noise and CNR at cor-onary CT angiography,thus it may provide the potentiality for reducing radiation exposure.