Ertl-Wagner Birgit B, Hoffmann Ralf-Thorsten, Bruning Roland, Herrmann Karin, Snyder Brad, Blume Jeffrey D, Reiser Maximilian F
Institute of Clinical Radiology, Klinikum Grosshadern, University of Munich, Marchioninistr 15, D-81377 Munich, Germany.
Radiology. 2004 May;231(2):528-35. doi: 10.1148/radiol.2312030543. Epub 2004 Mar 24.
To investigate image quality and vascular delineation of multi-detector row computed tomographic (CT) angiography at various kilovoltage settings.
Thirty patients were investigated with a standardized CT protocol, with three groups of 10 consecutive patients examined at 80, 120, and 140 kV, respectively. Three blinded readers independently evaluated images and graded image quality parameters, diagnostic confidence, and vascular delineation of intracranial arteries and veins. Vascular CT attenuation values, CT dose indices, and dose length products were assessed quantitatively. For data analysis, a Kruskal-Wallis nonparametric rank F test was used to identify trends and variables that required modeling attention. A proportional odds multinomial regression model was then fit with generalized estimating equations to account for the correlated nature of the data.
Image quality was rated higher with higher kilovoltage settings (P <.001). The severity of imaging artifacts was higher with lower kilovoltage settings (P <.001), while the subjectively rated vessel contrast was lower in the 80-kV group than in the 120-kV group and the 140-kV group (P <.05). Diagnostic confidence was higher in the 120-kV group and 140-kV group (P <.005). Vascular delineation was higher with higher kilovoltage settings for most arterial and venous structures. Differences were more significant for structures in close topographic proximity to bone and for subsegmental arteries and were less significant and, in parts, not significant for the main arterial branches and the large venous sinus. Attenuation values were higher with lower kilovoltage settings (P <.05). The mean dose length product could be reduced from 594 mGy. cm in the 140-kV group to 152 mGy.cm in the 80-kV group.
This multireader study of image quality and vessel delineation with cranial multi-detector row CT angiography at various kilovoltage settings demonstrated a superiority of higher voltages with most pronounced effects for vessels adjacent to bone and subsegmental arteries.
研究在不同千伏设置下多排螺旋计算机断层扫描（CT）血管造影的图像质量和血管显示情况。
30例患者采用标准化CT方案进行检查，分别有三组，每组连续10例患者，依次在80、120和140 kV下进行检查。三位不知情的阅片者独立评估图像，并对图像质量参数、诊断信心以及颅内动脉和静脉的血管显示情况进行评分。对血管CT衰减值、CT剂量指数和剂量长度乘积进行定量评估。数据分析时，采用Kruskal-Wallis非参数秩F检验来识别需要建模关注的趋势和变量。然后使用广义估计方程拟合比例优势多项回归模型，以考虑数据的相关性。
千伏设置越高，图像质量评分越高（P <.001）。千伏设置越低，成像伪影越严重（P <.001），而80 kV组主观评定的血管对比度低于120 kV组和140 kV组（P <.05）。120 kV组和140 kV组的诊断信心更高（P <.005）。对于大多数动脉和静脉结构，千伏设置越高，血管显示越好。对于与骨骼在地形上接近的结构以及亚段动脉，差异更为显著，而对于主要动脉分支和大静脉窦，差异较小，部分差异不显著。千伏设置越低，衰减值越高（P <.05）。平均剂量长度乘积可从140 kV组的594 mGy.cm降至80 kV组的152 mGy.cm。
这项关于不同千伏设置下头颅多排螺旋CT血管造影图像质量和血管显示的多阅片者研究表明，较高电压具有优势，对邻近骨骼的血管和亚段动脉影响最为明显。
