Dillinger Daniel, Overhoff Daniel, Froelich Matthias F, Kaatsch Hanns L, Booz Christian, Hagen Achim, Vogl Thomas J, Schönberg Stefan O, Waldeck Stephan
Department of Vascular Surgery and Endovascular Surgery, Bundeswehr Central Hospital, Rübenacher Straße 170, 56072 Koblenz, Germany.
Department of Radiology and Neuroradiology, Bundeswehr Central Hospital, Rübenacher Straße 170, 56072 Koblenz, Germany.
Diagnostics (Basel). 2024 Mar 15;14(6):626. doi: 10.3390/diagnostics14060626.
The aim of this study was to analyze the extent of dental metal artifacts in virtual monoenergetic (VME) images, as they often compromise image quality by obscuring soft tissue affecting vascular attenuation reducing sensitivity in the detection of dissections.
Neck photon-counting CT datasets of 50 patients undergoing contrast-enhanced trauma CT were analyzed. Hyperattenuation and hypoattenuation artifacts, muscle with and without artifacts and vessels with and without artifacts were measured at energy levels from 40 keV to 190 keV. The corrected artifact burden, corrected image noise and artifact index were calculated. We also assessed subjective image quality on a Likert-scale.
Our study showed a lower artifact burden and less noise in artifact-affected areas above the energy levels of 70 keV for hyperattenuation artifacts (conventional polychromatic CT images 1123 ± 625 HU vs. 70 keV VME 1089 ± 733 HU, = 0.125) and above of 80 keV for hypoattenuation artifacts (conventional CT images -1166 ± 779 HU vs. 80 keV VME -1170 ± 851 HU, = 0.927). Vascular structures were less hampered by metal artifacts than muscles (e.g., corrected artifact burden at 40 keV muscle 158 ± 125 HU vs. vessels -63 ± 158 HU < 0.001), which was also reflected in the subjective image assessment, which showed better ratings at higher keV values and overall better ratings for vascular structures than for the overall artifact burden.
Our research suggests 70 keV might be the best compromise for reducing metal artifacts affecting vascular structures and preventing vascular contrast if solely using VME reconstructions. VME imaging shows only significant effects on the general artifact burden. Vascular structures generally experience fewer metal artifacts than soft tissue due to their greater distance from the teeth, which are a common source of such artifacts.
本研究旨在分析虚拟单能（VME）图像中牙科金属伪影的程度，因为它们常常会掩盖软组织，影响血管衰减，降低夹层检测的敏感性，从而损害图像质量。
分析了50例接受对比增强创伤CT检查患者的颈部光子计数CT数据集。在40keV至190keV的能量水平下，测量了高密度和低密度伪影、有和无伪影的肌肉以及有和无伪影的血管。计算了校正后的伪影负荷、校正后的图像噪声和伪影指数。我们还采用李克特量表评估了主观图像质量。
我们的研究表明，对于高密度伪影，在能量水平高于70keV时，受伪影影响区域的伪影负荷较低且噪声较小（传统多色CT图像1123±625HU，而70keV的VME图像为1089±733HU，P = 0.125）；对于低密度伪影，在能量水平高于80keV时也是如此（传统CT图像-1166±779HU，而80keV的VME图像为-1170±851HU，P = 0.927）。血管结构受金属伪影的影响比肌肉小（例如，40keV时肌肉的校正伪影负荷为158±125HU，而血管为-63±158HU，P < 0.001），这也反映在主观图像评估中，在较高keV值时评分更高，血管结构的总体评分高于整体伪影负荷。
我们的研究表明，如果仅使用VME重建，70keV可能是减少影响血管结构的金属伪影和防止血管造影剂伪影的最佳折衷方案。VME成像仅对一般伪影负荷有显著影响。由于血管结构与牙齿（此类伪影的常见来源）的距离较远，其通常比软组织经历更少的金属伪影。
