双能量 CT 虚拟单能谱成像技术在脑动脉瘤夹闭术后评估中的应用

The application of monoenergetic imaging in postoperative evaluation of the patients with intracranial aneurysm clipping using dual energy CT angiography

目的：以常规颅脑 CTA 为对照，研究双能量 CT 单能谱成像用于颅内动脉瘤颈夹闭术后评估的最佳能量范围。方法：对36例患者40组双能量数据进行回顾性分析。采用双能量单能谱软件在60～100 keV 之间每隔10 keV 值进行单能量图像重组，平均加权120 kV 为常规 CTA 图像，共6组图像。分别测量每组图像伪影影响最重的脑组织和血管CT 值，评估线束硬化伪影和血管对比度，并对单能量和 CTA 图像质量进行主观评价。结果：60～100 keV 之间单能量图像的动脉瘤夹金属伪影分别为（116．9±73．0）、（72．4±37．3）、（49．8±27．0）、（34．8±20．7）和（26．7±18．2）HU。常规CTA 图像的硬化伪影（62．5±31．6）HU 与70～80 keV 单能量图像差异无统计学意义（P＞0．05），80～100 keV 的单能量图像硬化伪影低于常规 CTA。60～100 keV 单能量图像的血管对比度分别为（301．9±74．9）、（217．6±54．2）、（163．8±41．8）、（126．9±34．2）和（103．1±46．1）HU，常规 CTA 的血管对比度（183．5±48．8）HU 与70～80 keV 单能量图像差异无统计学意义（P＞0．05）。60～100 keV 和常规 CTA 图像质量为优和良的比例分别为20．0％、47．5％、85％、35％、15％、65％。结论：双能量 CT 成像用于颅内动脉瘤颈夹闭术后患者评估的最佳能量范围是70～80 keV，80 keV 有望成为最佳单能量成像点。

Using conventional CTA as control,to explore the optimal energy range for mono-energetic ima-ging of the dual-energy CT to evaluate the postoperative patient with intracranial aneurysm clipping.Methods：40 sets of du-al energy CT data from 36 patients were analyzed retrospectively.The dual-energy CT data were processed by using the mono-energetic software.Then single energy images were generated every 10keV ranging from 60 to 100 keV.The average weighted 120kV was set as conventional CTA image for comparison.In order to assess the beam hardening artifacts and vascular contrast,the CT value of cerebral tissue and blood vessels were measured,ROI were set on regions where were most severe affected by hardening artifacts.Reconstructed single energy images were assessed by two experienced radiolo-gists blindly.Results：The CT value of metal hardening artifact of aneurysm clip were （116.9 ± 73.0 ）,（72.4 ± 37.3 ）, （49.8±27.0）,（34.8±20.7）and （26.7±18.2）HU for each group ranging from 60 to 100keV respectively.There was sta-tistically significant difference between above CT value in each group and that in the conventional CTA image （62.5 ± 31.6）.The vascular contrast were （301.9 ± 74.9 ）,（217.6 ± 54.2 ）,（163.8 ± 41.8 ）,（126.9 ± 34.2 ）and （103.1 ± 46.1）HU for each group ranging from 60 to 100keV respectively.There was no statistically significant difference of vascu-lar contrast between the conventional CTA image （183.5±48.8）HU and 80 keV monoenergetic image.The ratios of excel-lent or good image quality of the single energy image were 20.0%,47.5%,85%,35.0%,15% for each group respectively and 65% for conventional CTA group.Conclusion：The optimal energy range of the dual-energetic imaging for postoperative evaluation of intracranial aneurysm neck clipping is from 70 to 80keV.The 80keV is suggested as the best setting point for single energy image because it has lower hardening artifacts while maintaining similar vascular contrast.