Diagnostic and Interventional Radiology (DIR), Heidelberg University Hospital, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany.
Eur J Radiol. 2020 Oct;131:109262. doi: 10.1016/j.ejrad.2020.109262. Epub 2020 Aug 31.
Investigation of potential improvements in dynamic CT perfusion measurements by exploitation of improved visualization of contrast agent in virtual monoenergetic reconstructions of images acquired with dual-energy computed tomography (DECT).
For 17 patients with pancreatic carcinoma, dynamic dual-source DECT acquisitions were performed at 80kV/Sn140kV every 1.5 s over 51 s. Virtual monoenergetic images (VMI) were reconstructed for photon energies between 40 keV and 150 keV (5 keV steps). Using the maximum-slope model, perfusion maps of blood flow were calculated from VMIs and 80kV images and compared quantitatively with regard to blood flow measured in regions of interest in healthy tissue and carcinoma, standard deviation (SD), and absolute-difference-to-standard-deviation ratio (ADSDR) of measurements.
On average, blood flow calculated from VMIs increased with increasing energy levels from 114.3 ± 37.2 mL/100 mL/min (healthy tissue) and 45.6 ± 25.3 mL/100 mL/min (carcinoma) for 40 keV to 128.6 ± 58.9 mL/100 mL/min (healthy tissue) and 75.5 ± 49.8 mL/100 mL/min (carcinoma) for 150 keV, compared to 114.2 ± 37.4 mL/100 mL/min (healthy tissue) and 46.5 ± 26.6 mL/100 mL/min (carcinoma) for polyenergetic 80kV. Differences in blood flow between tissue types were significant for all energies. Differences between perfusion maps calculated from VMIs and 80kV images were not significant below 110 keV. SD and ADSDR were significantly better for perfusion maps calculated from VMIs at energies between 40 keV and 55 keV than for those calculated from 80kV images. Compared to effective dose of dynamic 80kV acquisitions (4.6 ± 2.2mSv), dose of dynamic DECT/VMI acquisitions (8.0 ± 3.7mSv) was higher.
Perfusion maps of blood flow based on low-energy VMIs between 40 keV and 55 keV offer improved robustness and quality of quantitative measurements over those calculated from 80kV image data (reference standard), albeit at increased patient radiation exposure.
通过利用双能 CT（DECT）采集图像的虚拟单能量重建中对比剂可视化的改善，研究动态 CT 灌注测量的潜在改进。
对 17 例胰腺癌患者进行 80kV/Sn140kV 双源 DECT 采集，1.5s 采集一次，共采集 51s。对 40keV 至 150keV（5keV 步长）的光子能量进行虚拟单能量图像（VMI）重建。使用最大斜率模型，从 VMIs 和 80kV 图像计算血流灌注图，并对健康组织和癌组织感兴趣区域的血流测量值、标准偏差（SD）和测量值与标准偏差的绝对差值比（ADSDR）进行定量比较。
平均而言，从 VMIs 计算的血流量随着能量水平的增加而增加，从 40keV 的 114.3±37.2mL/100mL/min（健康组织）和 45.6±25.3mL/100mL/min（癌组织）增加到 150keV 的 128.6±58.9mL/100mL/min（健康组织）和 75.5±49.8mL/100mL/min（癌组织），而多能 80kV 的值分别为 114.2±37.4mL/100mL/min（健康组织）和 46.5±26.6mL/100mL/min（癌组织）。所有能量下，组织类型之间的血流量差异均有统计学意义。在低于 110keV 时，从 VMIs 和 80kV 图像计算的灌注图之间的差异无统计学意义。与从 80kV 图像计算的灌注图相比，在 40keV 至 55keV 之间的 VMIs 计算的灌注图的 SD 和 ADSDR 更好。与动态 80kV 采集的有效剂量（4.6±2.2mSv）相比，动态 DECT/VMI 采集的剂量（8.0±3.7mSv）更高。
基于 40keV 至 55keV 的低能 VMIs 的血流灌注图在定量测量的稳健性和质量方面优于基于 80kV 图像数据（参考标准）的灌注图，尽管患者的辐射暴露增加。
