Xu Jun, Shen Jian, Dong Qian, Gui Shen, Wang Jing, Lei Zi-Qiao, Hu Xiao-Li, Luo Kun
Department of Radiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Hubei Provincial Clinical Research Center for Precision Radiology & Interventional Medicine, Wuhan, China.
Quant Imaging Med Surg. 2025 Jan 2;15(1):515-523. doi: 10.21037/qims-24-834. Epub 2024 Dec 30.
The scanning trigger threshold affects image quality. The aim of this study was to investigate the effect of different scanning trigger thresholds on brain computed tomography angiography (CTA) image quality.
In this prospective study, 80 patients undergoing brain CTA examinations with dual-layer CT (DLCT) were randomly divided into group A and group B, with 40 patients in each group. In group A, the CT value of the internal carotid artery at the level of the fourth cervical vertebra was monitored, and the scan was initiated once the CT value reached 100 Hounsfield units (HU). In group B, the trigger threshold was set at 60 HU, with all other parameters kept consistent with those of group A. Finally, the image quality of the 50-keV virtual monoenergetic images (VMIs) was evaluated, including the CT values of the internal carotid artery (CT), middle cerebral artery (CT), sinus confluence (CT), cerebral white matter (CT), background noise (BN), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and subjective scoring.
All images met the diagnostic imaging requirements. Group B showed significantly lower values than did group A for CT (371.97±51.81 442.64±83.39 HU), CT (345.80±50.72 405.87±82.81 HU), CT (90.44±21.30 138.87±37.37 HU), CT (31.98±5.66 38.86±5.68 HU), SNR (108.64±21.05 126.79±30.87), and CNR (98.58±19.72 114.65±29.56) (all P values <0.05) but the value for BN was not significantly different (P>0.05). However, the subjective scores in group B were significantly higher than those in group A (χ=19.013; P<0.05).
For brain CTA imaging in DLCT (50 keV VMIs), lowering the scan trigger threshold to 60 HU helped to reduce venous artifacts and improve image quality (as evidenced by improved subjective scores) and also suggests the potential for a further reduction of the contrast dose.
扫描触发阈值会影响图像质量。本研究旨在探讨不同扫描触发阈值对脑部计算机断层血管造影（CTA）图像质量的影响。
在这项前瞻性研究中，80例行双层CT（DLCT）脑部CTA检查的患者被随机分为A组和B组，每组40例。A组监测第四颈椎水平颈内动脉的CT值，当CT值达到100亨氏单位（HU）时启动扫描。B组触发阈值设定为60 HU，其他所有参数与A组保持一致。最后，评估50 keV虚拟单能图像（VMI）的图像质量，包括颈内动脉（CT）、大脑中动脉（CT）、窦汇（CT）、脑白质（CT）的CT值、背景噪声（BN）、信噪比（SNR）、对比噪声比（CNR）以及主观评分。
所有图像均符合诊断成像要求。B组的CT（371.97±51.81对442.64±83.39 HU）、CT（345.80±50.72对405.87±82.81 HU）、CT（90.44±21.30对13当扫描触发阈值降低至60 HU时，有助于减少静脉伪影并提高图像质量（主观评分提高证明），同时也提示了进一步降低对比剂剂量的可能性。8.87±37.37 HU）、CT（31.98±5.66对38.86±5.68 HU）、SNR（108.64±21.05对126.79±30.87）和CNR（98.58±19.72对114.65±29.56）的值均显著低于A组（所有P值<0.05），但BN值差异无统计学意义（P>0.05）。然而，B组的主观评分显著高于A组（χ= 19.013；P<0.05）。
对于DLCT（50 keV VMI）脑部CTA成像，
