Wang Rui, Schoepf U Joseph, Wu Runze, Nance John W, Lv Biao, Yang Hua, Li Fang, Lu Dongxu, Zhang Zhaoqi
From the *Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China; †Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC; ‡Siemens Healthcare China, Beijing, China; §The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Hospital, Baltimore, MD; and ∥Affiliated Hospital, Hebei United University, Hebei, China.
J Comput Assist Tomogr. 2014 Mar-Apr;38(2):179-84. doi: 10.1097/RCT.0000000000000005.
To investigate the diagnostic accuracy of coronary computed tomographic (CT) angiography (CCTA) using filtered back projection (FBP) and sinogram-affirmed iterative reconstruction (SAFIRE) of different strength factors with invasive coronary angiography as the reference standard.
Fifty consecutive patients (32 men and 18 women) prospectively underwent electrocardiogram-triggered CCTA on a dual-source CT system. The acquisition window was set depending on the heart rate (HR): HR of less than 60 beats per minute (bpm) at the 70% RR interval, 61 to 80 bpm at 30% to 80% RR interval, and greater than 80 bpm at 30% to 50% RR interval; 100 kV and 359 to 377 mA s for patients with a body mass index of less than 24 kg/m, and 410 to 438 mA s at 120 kV for patients with a body mass index of 24 kg/m or greater. Image data were reconstructed using both FBP and SAFIRE. Sinogram-affirmed iterative reconstruction series were reconstructed using 3 different strength factors. Two blinded observers independently assessed the image quality and image impression of each coronary segment using a 4-point scale (1, non-diagnostic; and 4, excellent). Image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured. Filtered back projection and all SAFIRE series were independently evaluated for coronary artery stenosis (>50%), and their diagnostic accuracy was compared with invasive coronary angiography.
Statistically significant increases in SNR and CNR were obtained when higher strength factors were used. The highest SNR and CNR were found with the highest SAFIRE strength factor of 5; however, this strength also resulted in a more unfamiliar, "plasticlike" image appearance. Imaging quality scores of FBP and different SAFIRE strengths were 3.37 ± 0.49, 3.41 ± 0.47, 3.52 ± 0.30, and 3.48 ± 0.35, respectively (P < 0.001). The diagnostic accuracies were 92.91%, 93.76%, 95.28%, and 94.94% on per-segment level, respectively (P = 0.993). A tendency toward higher diagnostic performance was observed with SAFIRE strength factor 3 on per-segment analysis, albeit without reaching statistical significance. The effective radiation dose equivalent was 5.7 ± 1.6 mSv.
Sinogram-affirmed iterative reconstruction provides significant improvements in image noise, SNR, and CNR compared with FBP, which are progressive with increasing SAFIRE strength factors. Sinogram-affirmed iterative reconstruction strength factor 3 or 5 is recommended for use with CCTA.
以有创冠状动脉造影为参考标准，研究使用滤波反投影（FBP）和不同强度因子的正弦图确认迭代重建（SAFIRE）技术的冠状动脉计算机断层扫描（CT）血管造影（CCTA）的诊断准确性。
连续50例患者（32例男性和18例女性）前瞻性地在双源CT系统上接受心电图触发的CCTA检查。采集窗口根据心率（HR）设置：RR间期70%时心率小于60次/分钟（bpm），RR间期30%至80%时心率61至80 bpm，RR间期30%至50%时心率大于80 bpm；体重指数小于24 kg/m²的患者采用100 kV和359至377 mAs，体重指数为24 kg/m²或更高的患者采用120 kV和410至438 mAs。图像数据使用FBP和SAFIRE进行重建。使用3个不同强度因子重建正弦图确认迭代重建系列。两名盲法观察者使用4分制（1分，非诊断性；4分，优秀）独立评估每个冠状动脉节段的图像质量和图像印象。测量图像噪声、信噪比（SNR）和对比噪声比（CNR）。对滤波反投影和所有SAFIRE系列独立评估冠状动脉狭窄（>50%）情况，并将其诊断准确性与有创冠状动脉造影进行比较。
使用较高强度因子时，SNR和CNR在统计学上有显著提高。SAFIRE最高强度因子5时SNR和CNR最高；然而，该强度也导致图像外观更不熟悉，类似“塑料”。FBP和不同SAFIRE强度的成像质量评分分别为3.37±0.49、3.41±0.47、3.52±0.30和3.48±0.35（P<0.001）。在每个节段水平上，诊断准确性分别为92.91%、93.76%及95.28%和94.94%（P=0.993）。在每个节段分析中，观察到SAFIRE强度因子3有更高诊断性能的趋势，尽管未达到统计学意义。有效辐射剂量当量为5.7±1.6 mSv。
与FBP相比，正弦图确认迭代重建在图像噪声、SNR和CNR方面有显著改善，且随着SAFIRE强度因子增加而逐步提高。建议在CCTA中使用正弦图确认迭代重建强度因子3或5。
