Department of Radiology, Cardiac Imaging, University Hospital Zurich, Ramistrasse 100, NUK C 42, CH-8091 Zurich, Switzerland.
J Cardiovasc Comput Tomogr. 2013 Jan-Feb;7(1):25-31. doi: 10.1016/j.jcct.2013.01.004. Epub 2013 Jan 19.
New technology combining dual-energy CT with the latest gemstone detectors for spectral imaging (GSI) can be used to synthesize monochromatic images that mimic images as if different monochromatic x-ray sources were used.
The aim of the study was to evaluate the optimal combination of monochromatic image energy and adaptive statistical iterative reconstruction (ASiR) for monochromatic reconstruction of coronary CT angiography (CTA) images with the use of GSI.
Twenty consecutive patients underwent coronary CTA on a GSI capable 64-slice CT scanner (Discovery CT 750 High Definition, GE Healthcare). In 7 sets of monochromatic images (60, 65, 70, 75, 80, 90, and 110 keV; each with increasing contributions of ASiR, ie, 0%, 20%, 40%, 60%, and 80%; n = 35 reconstructions per patient), signal-to-noise (aortic root) and contrast-to-noise (left main artery) ratios were assessed. Signal-to-noise ratio, contrast-to-noise ratio, and image quality (graded on a 5-point Likert scale) were assessed in all above monochromatic reconstructions and compared with the respective standard (conventional polychromatic) image.
Compared with conventional polychromatic images, reconstructions with 60 keV and 80% ASiR showed the highest improvement in contrast-to-noise (144%; P < 0.001) and signal-to-noise ratio (173%; P < 0.001). Image quality reached a plateau at 65-75 keV with 40%-60% ASiR blending, yielding a maximal image quality score improvement of 50% compared with conventional imaging (P < 0.001).
In coronary CTA with low radiation technique (mean radiation dose, 1.8 ± 0.7 mSv), GSI with monochromatic reconstructions (65-75 keV) and ASiR (40%-60%) offers significant noise reduction and image quality improvement.
结合双能 CT 和最新的宝石探测器进行光谱成像（GSI）的新技术可用于合成模拟使用不同单色 X 射线源的单色图像。
本研究旨在评估使用 GSI 对冠状动脉 CT 血管造影（CTA）图像进行单色重建的最佳单色图像能量和自适应统计迭代重建（ASiR）组合。
连续 20 例患者在配备 GSI 的 64 层 CT 扫描仪（GE Healthcare 的 Discovery CT 750 High Definition）上进行冠状动脉 CTA。在 7 组单色图像（60、65、70、75、80、90 和 110 keV；每个图像的 ASiR 贡献逐渐增加，即 0%、20%、40%、60%和 80%；每个患者 35 个重建）中，评估信号噪声比（主动脉根部）和对比噪声比（左主干动脉）。在所有上述单色重建中评估信号噪声比、对比噪声比和图像质量（5 分 Likert 量表），并与相应的标准（常规多色）图像进行比较。
与常规多色图像相比，60 keV 和 80%ASiR 的重建显示对比度噪声比（144%；P<0.001）和信号噪声比（173%；P<0.001）的提高最高。在 65-75 keV 时，40%-60%ASiR 混合达到图像质量平台，与常规成像相比，图像质量评分提高了 50%（P<0.001）。
在低辐射技术（平均辐射剂量 1.8±0.7 mSv）的冠状动脉 CTA 中，GSI 与单色重建（65-75 keV）和 ASiR（40%-60%）相结合可显著降低噪声并提高图像质量。
