使用70 kVp、高螺距采集和正弦图确认迭代重建技术的下肢CT血管造影的图像质量和辐射剂量。
Image quality and radiation dose of lower extremity CT angiography using 70 kVp, high pitch acquisition and sinogram-affirmed iterative reconstruction.
作者信息
Qi Li, Meinel Felix G, Zhou Chang Sheng, Zhao Yan E, Schoepf U Joseph, Zhang Long Jiang, Lu Guang Ming
机构信息
Department of Medical Imaging, Jinling Hospital, Clinical School of South Medical University, Nanjing, Jiangsu, China.
Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, South Carolina, United States of America.
出版信息
PLoS One. 2014 Jun 10;9(6):e99112. doi: 10.1371/journal.pone.0099112. eCollection 2014.
OBJECTIVES
The purpose of this study was to assess image quality and radiation dose of lower extremity CT angiography (CTA) with 70 kVp, high pitch acquisition and sinogram-affirmed iterative reconstruction (SAFIRE).
METHODS
Lower extremity CTAs were performed on 44 patients: 22 patients were examined using protocol A (120 kVp, pitch of 0.85 and 120 ml of contrast agent on a first-generation dual-source CT) (120 kVp group) and 22 patients were evaluated with protocol B (70 kVp, pitch of 2.2 and 80 ml of contrast agent on a second-generation dual-source CT) (70 kVp group). Images from the 120 kVp group were reconstructed with filtered back projection (FBP) and images from the 70 kVp group with SAFIRE. The attenuation, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Two radiologists subjectively assessed image quality of lower extremity arteries, plantar arterial enhancement and venous contamination of all patients. Radiation dose was compared between the two groups.
RESULTS
Higher mean intravascular attenuation was obtained in the 70 kVp group (70 vs. 120 kVp group, 555.4 ± 83.4 HU vs. 300.9 ± 81.4 HU, P<0.001), as well as image noise (20.0 ± 2.8 HU vs. 17.5 ± 3.2 HU, P = 0.010), SNR (32.0 ± 7.0 vs. 19.1 ± 6.9, P<0.001) and CNR (28.1 ± 6.6 vs 15.9 ± 6.3, P<0.001). No difference in subjective image quality and plantar arterial enhancement was found between 120 kVp group and 70 kVp group (all P>0.05). The venous contamination score was 1.5 ± 0.8 for 120 kVp group while no venous contamination was found in 70 kVp group. The inter-observer agreement was moderate to good for both groups (0.515∼1, P<0.001). The effective dose was lower in 70 kVp group (0.3 ± 0.1 mSv) than in 120 kVp group (1.6 ± 0.7 mSv)(P<0.001).
CONCLUSIONS
Lower extremity CTA using 70 kVp, high pitch acquisition and SAFIRE, except increasing imaging noise, allows for lower radiation dose and contrast material volume without compromising image quality.
目的
本研究旨在评估采用70 kVp、高螺距采集和正弦图确认迭代重建（SAFIRE）技术的下肢CT血管造影（CTA）的图像质量和辐射剂量。
方法
对44例患者进行下肢CTA检查：22例患者采用方案A（120 kVp，螺距0.85，在第一代双源CT上使用120 ml造影剂）（120 kVp组），22例患者采用方案B（70 kVp，螺距2.2，在第二代双源CT上使用80 ml造影剂）（70 kVp组）进行评估。120 kVp组的图像采用滤波反投影（FBP）重建，70 kVp组的图像采用SAFIRE重建。计算衰减、图像噪声、信噪比（SNR）和对比噪声比（CNR）。两名放射科医生对所有患者的下肢动脉图像质量、足底动脉强化和静脉污染进行主观评估。比较两组之间的辐射剂量。
结果
70 kVp组的平均血管内衰减更高（分别为70 kVp组和120 kVp组，555.4±83.4 HU对300.9±81. HU，P<0.001），图像噪声也是如此（20.0±2.8 HU对17.5±3.2 HU，P = 0.010），SNR（32.0±7.0对19.1±6.9, P<0.001）和CNR（28.1±6.6对15.9±6.3, P<0.001）。120 kVp组和70 kVp组之间在主观图像质量和足底动脉强化方面未发现差异（所有P>0.05）。120 kVp组的静脉污染评分为1.±0.8，而70 kVp组未发现静脉污染。两组的观察者间一致性为中度至良好（0.515∼1，P<0.001）。70 kVp组的有效剂量（0.3±0.1 mSv）低于120 kVp组（1.6±0.7 mSv）（P<0.001）。
结论
采用70 kVp、高螺距采集和SAFIRE技术的下肢CTA，除了增加成像噪声外，在不影响图像质量的情况下可降低辐射剂量和造影剂用量。
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