迭代重建算法在双源CT三低方案冠状动脉血管成像中的应用价值

The application value of sinogram affirmed iterative reconstruction （ SAFIRE ） algorithm in the coronary computed tomography angiography（CCTA） with the tri-low scheme of dual source CT

目的探讨迭代重建（SAFIRE）算法在双源CT三低方案（低管电压、低剂量对比剂、低流速注射）冠状动脉血管造影（CCTA）中的应用价值。方法连续选取120例体质量指数（BMI）18．6～24．9kg／m2和心率〈65次／min的患者，均使用对比剂碘海醇350mgl／ml，其中包括滤波反投影技术（FBP）组和SAFIRE组，每组60例。FBP组采用120kV管电压、对比剂剂量0．9ml／kg、注射流速5．0ml／s，进行前瞻性心电门控扫描，图像重建采用FBP；SAFIRE组采用80kV管电压、对比剂剂量0．7ml／kg、注射速率3．5ml／s，进行前瞻性心电门控大螺距扫描，图像重建采用SAFIRE。测量两组动脉管腔内及左心室底部肌肉的CT强化值和噪声，计算信噪比（SNR）及对比噪声比（CNR）。采用双盲法对冠状动脉节段以4分法进行评价，其中1分为不可诊断图像。记录每一个患者的平均容积CT剂量指数（CTDIvol）和剂量长度乘积（DLP），并计算有效剂量。结果两组动脉管腔内CT值、图像噪声、SNR、CNR，差异均无统计学意义（P〉0．05）；SAFIRE组有效剂量（0．39±0．02）mSv较FBP组显著降低（4．99±1．36）mSv，差异有统计学意义（t=26．31，P〈0．05）。结论在BMI为18．6—24．9kg／m2、心率〈65次／min的患者中，应用双源CT前瞻性心电触发大螺距三低方案联合迭代重建算法冠状动脉血管成像，能得到满意的图像，又降低了辐射剂量。

Objective To investigate the application value of sinogram affirmed iterative reconstruction （SAFIRE） algorithm in the coronary computed tomography angiograpby（CCTA） with tri-low scheme （low tube voltage, low dose contrast agent, low flow rate injection） of the dual-source CT. Methods Totally 120 patients with body mass index （BMI） of 18.6 to 24.9 kg/m 2, heart rate 〈 65 b/min were selected continuously and the contrast agent iohexol （350 mgI/ml） was used. The patients were divided equally into two groups： FBP group, using 120 kV tube voltages, contrast media dose of 0.9 ml/kg, and injection rate of 5.0 ml/s to carry out prospective ECG-trigger scanning, and image reconstruction based on filtered back projection （FBP） algorithm; SAFIRE group, using 80 kV tube voltage, contrast media dosage 0. 7 ml/kg, injection rate of 3.5 ml/s to carry out prospective ECG-trigger high-pitch scanning, and iterative reconstruction technique. CT values of enhanced images and noise of two groups of arterial lumen and left ventricular bottom muscle were measured, and the signal-to-noise ratio （SNR） and contrast to noise ratio （CNR） were calculated. The method of double blind was used to evaluate coronary artery in 4-point scale （ 1 = non-diagnostic ）. The average volume CT dose index （CTDIvo1） and the dose length product （DLP） for each patient were recorded and the effective radiation doses were calculated. Results The difference in the CT values, image noise, SNR, CNR between the two groups was not statistically significantly（ P 〉 0.05 ）. The effective dose in SAFIRE group was （0.39 ± 0.02） mSv significantly lower than that in FBP group of （4. 99 ±1.36） mSv （t =26.31, P 〈0.01）. Conclusions For the patients with body mass index （BMI） 18.6 to 24. 9 kg/m2 , HR 〈 65 b/min, the application of prospective ECG-trigger high pitch tri-low scheme combined with the iterative reconstruction algorithm in dual-source CT coronary angiography, can obtain the qualified image with lower radiation dose.