Ananthakrishnan Lakshmi, Duan Xinhui, Rajiah Prabhakar, Soesbe Todd C, Lewis Matthew A, Xi Yin, Fielding Julia R, Lenkinski Robert E, Leyendecker John R, Abbara Suhny
From the UT Southwestern Medical Center, Dallas, TX.
J Comput Assist Tomogr. 2018 Nov/Dec;42(6):959-964. doi: 10.1097/RCT.0000000000000763.
Spectral detector computed tomography (SDCT) is a new CT technology that uses a dual-layer detector to perform energy separation. We aim to assess 3 clinical concepts using a phantom model: noise profile across the virtual monoenergetic (VME) spectrum, accuracy of iodine quantification, and virtual noncontrast (VNC) reconstructions' ability to remove iodine contribution to attenuation.
Six vials containing varying concentrations of iodinated contrast (0-6 mg/mL) diluted in water were placed in a water bath and scanned on an SDCT scanner. Virtual monoenergetic (40-200 keV at 10-keV increments), iodine-no-water, and VNC reconstructions were created. Attenuation (in Hounsfield units [HU]), VME noise at each energy level, CT-derived iodine concentration, and VNC attenuation were recorded.
Virtual monoenergetic noise was improved at all energies compared with conventional images (conventional, 9.8-11.2; VME, 7.5-9.5). Noise profile showed a slightly higher image noise at 40 keV, but was otherwise relatively flat across the energy spectrum. On iodine-no-water reconstructions, measured varied from actual iodine concentration by ±0.1 mg/mL (SD, 0.16-0.36). Virtual noncontrast attenuation was within 5 HU of water attenuation at all iodine concentrations.
Reconstructions of SDCT show lower VME image noise, accurate iodine quantification, and VNC attenuation values within 5 HU of expected in a phantom model.
光谱探测器计算机断层扫描（SDCT）是一种利用双层探测器进行能量分离的新型CT技术。我们旨在使用体模模型评估三个临床概念：虚拟单能（VME）光谱上的噪声分布、碘定量的准确性以及虚拟平扫（VNC）重建去除碘对衰减贡献的能力。
将六个装有不同浓度（0 - 6 mg/mL）碘化造影剂稀释于水中的小瓶置于水浴中，并在SDCT扫描仪上进行扫描。创建虚拟单能（40 - 200 keV，以10 keV为增量）、碘水分离和VNC重建图像。记录衰减值（以亨氏单位[HU]表示）、每个能量水平的VME噪声、CT衍生的碘浓度以及VNC衰减值。
与传统图像相比，所有能量水平下的虚拟单能噪声均有所改善（传统图像，9.8 - 11.2；VME，7.5 - 9.5）。噪声分布显示在40 keV时图像噪声略高，但在整个能量谱上相对较为平坦。在碘水分离重建图像上，测量的碘浓度与实际碘浓度的差异在±0.1 mg/mL范围内（标准差，0.16 - 0.36）。在所有碘浓度下，虚拟平扫衰减值与水的衰减值相差在5 HU以内。
在体模模型中，SDCT重建显示出更低的VME图像噪声、准确的碘定量以及VNC衰减值在预期值的5 HU范围内。
