Li Guang, Rednam Nikita, Kundra Vikas
Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, 22 S. Greene St., Baltimore, MD, 21201, USA.
Heliyon. 2024 Jul 26;10(15):e35210. doi: 10.1016/j.heliyon.2024.e35210. eCollection 2024 Aug 15.
The recent shortage of iodine-based intravenous contrast and its cost highlight the need for limiting dose and alterative agents.
To quantify radiodensity (Hounsfield Units, HU) improvement and potential iodine dose reduction with low keV imaging compared to conventional polyenergetic reconstructions on dual source (DSCT) and dual layer (DLCT) CT and to assess potential utility of non-iodine gadolinium-alternatives with low keV imaging.
This phantom study used dilutions of three commercially-available contrast agents scanned by DSCT and DLCT. Conventional polyenergetic and virtual monoenergetic images (VMI) were reconstructed of each of five dilutions at five keV levels. HU and signal-to-noise ratios were compared among iodine- and gadolinium-based contrast agents.
Iodine- and gadolinium-based contrast agent HU increased inversely to keV for the same dilution in both scanners. At the lowest keV setting (40 keV), iodine-based contrast agent HU in VMIs with DLCT and DSCT were approximately 300 % and 400 % of conventional, respectively. Gd-based contrast agent HU in VMIs at low keV were similar to or better than conventional iodine HU. Comparing the dual energy CTs, although HU from iodine and gadolinium-based contrast agents for conventional polyenergetic reconstructions was similar, HU in VMIs of DSCT were right shifted compared to DLCT by ∼10 keV lower.
Depending on CT scanner type, 1/3 to 1/4 dose of iodinated contrast at 40 keV provides HU similar to full dose conventional acquisition, suggesting 1/3-1/4 dose may be adequate clinically at 40 keV. Depending on the Gd-based contrast and CT type, Gd-based contrast at 40 keV provides similar or greater HU compared to conventional acquisitions with iodinated contrast, suggesting Gd-based contrast at 40 keV may serve as an alternative to iodinated contrast. HU on VMI images is scanner dependent, suggesting scanner-dependent protocol optimization and potentially monoenergy HU calibration between scanners is needed.
近期基于碘的静脉造影剂短缺及其成本凸显了限制剂量和寻找替代剂的必要性。
与双源（DSCT）和双层（DLCT）CT上的传统多能重建相比，量化低keV成像时的放射密度（亨氏单位，HU）改善情况以及潜在的碘剂量降低，并评估低keV成像时非碘钆替代剂的潜在效用。
本模型研究使用了三种市售造影剂的稀释液，通过DSCT和DLCT进行扫描。对五种稀释液在五个keV水平下分别重建传统多能图像和虚拟单能图像（VMI）。比较了基于碘和钆的造影剂之间的HU和信噪比。
在两台扫描仪中，对于相同的稀释液，基于碘和钆的造影剂的HU随keV呈反比增加。在最低keV设置（40keV）时，DLCT和DSCT的VMI中基于碘的造影剂的HU分别约为传统造影剂的300%和400%。低keV时VMI中基于钆的造影剂的HU与传统碘造影剂的HU相似或更好。比较双能CT，尽管传统多能重建中基于碘和钆的造影剂的HU相似，但DSCT的VMI中的HU比DLCT右移了约10keV。
根据CT扫描仪类型，40keV时1/3至1/4剂量的碘化造影剂提供的HU与全剂量传统采集相似，表明40keV时1/3 - 1/4剂量在临床上可能足够。根据基于钆的造影剂和CT类型，40keV时基于钆的造影剂与传统碘化造影剂采集相比提供相似或更高的HU，表明40keV时基于钆的造影剂可作为碘化造影剂的替代品。VMI图像上的HU取决于扫描仪，表明需要根据扫描仪进行协议优化以及潜在的扫描仪间单能HU校准。
