双层光谱探测器CT下肢CT血管造影中低剂量对比剂的可行性
Feasibility of low-dose contrast media in run-off CT angiography on dual-layer spectral detector CT.
作者信息
Ren Haiyan, Zhen Yanhua, Gong Zheng, Wang Chuanzhuo, Chang Zhihui, Zheng Jiahe
机构信息
Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, China.
出版信息
Quant Imaging Med Surg. 2021 May;11(5):1796-1804. doi: 10.21037/qims-20-925.
BACKGROUND
The aim of the present study was to assess the feasibility of applying low-dose contrast media (CM), and to explore the optimal virtual monoenergetic images (VMIs) in run-off computed tomography (CT) angiography (CTA) on dual-layer spectral detector CT (SDCT).
METHODS
Forty patients were randomly assigned into a control group using routine volume CM (group A) and an experimental group using half-volume CM (group B). In groups A and B, 120 kVp polychromatic conventional images were generated via hybrid iterative reconstruction algorithm defined as A1 and B1, respectively. Additionally, in group B, VMIs (range, 40-120 keV) were reconstructed via a spectral reconstruction algorithm defined as B2-B10. Vascular attenuation, noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and radiation dose were evaluated. Subjective evaluation was performed using a 5-point scale.
RESULTS
The patient demographics and radiation dose demonstrated no significant difference between groups A and B [dose length product (DLP): 1,823.45±512.68 2,014.40±453.25 mGy·cm, P=0.229; volume CT dose index: 14.92±3.40 16.26±2.85 mGy, P=0.208; the effective dose (ED): 10.82±3.02 11.88±2.67 mSv, P=0.229]. The mean vascular attenuation was higher in group B2 (40 keV) and was lower in group B3 (50 keV) in comparison with that in group A1 (487.07±154.21 414.35±71.66 HU, 329.90±100.25 414.35±71.66 HU, P>0.05). Compared with group A1, the mean noise was similar in group B2 (40 keV) and was lower in group B1 and groups B3-B10 (50-120 keV) (14.81±5.67 17.29±4.70 HU, P>0.05; 6.75±1.23-11.26±3.24 17.29±4.70 HU, P<0.05). The mean SNR and CNR in group B2 (40 keV), as well as the mean SNR in group B3 (50 keV), were significantly higher than those of group A1 (38.21±7.52 28.25±7.20, 32.70±7.79 24.54±6.60, 32.85±7.10 28.25±7.20, P<0.05), and the mean CNR in group B3 (50 keV) was similar to that in group A1 (26.66±7.32 24.54±6.60, P>0.05). Scores of subjective image quality (IQ) in group B2 (40 keV) and B3 (50 keV) were similar to those in group A1 {5 [4.25, 5] 5 [4, 5], 5 [5, 5] 5 [4, 5], P>0.05}, and showed a declining trend in group B4 (60 keV) {4 [4, 5] 5 [4, 5], P>0.05}.
CONCLUSIONS
It is feasible to perform run-off CTA using low-dose CM with VMI on SDCT. The VMIs at 40-50 keV were the optimal choice and did not compromise IQ.
背景
本研究的目的是评估应用低剂量对比剂（CM）的可行性，并在双层光谱探测器CT（SDCT）的CT血管造影（CTA）中探索最佳的虚拟单能量图像（VMI）。
方法
40例患者被随机分为使用常规剂量CM的对照组（A组）和使用半量CM的实验组（B组）。在A组和B组中，分别通过混合迭代重建算法生成120 kVp的多色常规图像，定义为A1和B1。此外，在B组中，通过光谱重建算法重建40 - 120 keV范围内的VMI，定义为B2 - B10。评估血管衰减、噪声、信噪比（SNR）、对比噪声比（CNR）和辐射剂量。使用5分制进行主观评估。
结果
A组和B组患者的人口统计学数据和辐射剂量无显著差异[剂量长度乘积（DLP）：1,823.45±512.68对2,014.40±453.25 mGy·cm，P = 0.229；容积CT剂量指数：14.92±3.40对16.26±2.85 mGy，P = 0.208；有效剂量（ED）：10.82±3.02对11.88±2.67 mSv，P = 0.229]。与A1组相比，B2组（40 keV）的平均血管衰减较高，B3组（50 keV）较低（487.07±154.21对414.35±71.66 HU，329.90±100.25对414.35±71.66 HU，P>0.05）。与A1组相比，B2组（40 keV）的平均噪声相似，B1组以及B3 - B10组（50 - 120 keV）较低（14.81±5.67对17.29±4.70 HU，P>0.05；6.75±1.23 - 11.26±3.24对17.29±4.70 HU，P<0.05）。B2组（40 keV）的平均SNR和CNR以及B3组（50 keV）的平均SNR显著高于A1组（38.21±7.52对28.25±7.20，32.70±7.79对24.54±6.60，32.85±7.10对28.25±7.20，P<0.05），B3组（50 keV）的平均CNR与A1组相似（26.66±7.32对24.54±6.60，P>0.05）。B2组（40 keV）和B3组（50 keV）的主观图像质量（IQ）评分与A1组相似{5[4.25, 5]对5[4, 5]，5[5, 5]对5[4, 5]，P>0.05}，且在B4组（60 keV）呈下降趋势{4[4, 5]对5[4, 5]，P>0.05}。
结论
在SDCT上使用低剂量CM和VMI进行CTA是可行的。40 - 50 keV的VMI是最佳选择，且不影响图像质量。
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