双能CT虚拟单能联合迭代重建技术对门静脉精准成像

The Combination of Virtual Monoenergetic and Iterative Reconstruction by Dual-energy CT to Precision Imaging of Portal Vein

目的:探索双源双能CT虚拟单能技术联合迭代重建提高门静脉成像质量的价值。方法:本研究前瞻性纳入30例患者,所有患者均采用双能量门静脉增强扫描,结合不同迭代强度(1、3、5级)进行数据重建,再对三组迭代重建数据分别进行虚拟单能量成像(40KeV、60KeV、80KeV、100KeV、120KeV、140keV)和传统120KeV混合能成像,最终每位患者获得21组图像。然后由2位放射科医生独立测量每组图像感兴趣区的平均CT值、噪声、信噪比(SNR)、对比噪声比(CNR),还对每组图像质量进行主观评分。采用组内相关系数(Intraclass correlation coefficient, ICC)对两组独立测量数据进行一致性评价,而各指标组间比较采用方差分析。结果:两位放射科医生测量的门脉主干CT值、CNR、图像噪声及主观评分一致性极好,其ICC分别为0.95、0.93、0.87、0.80。各图像质量客观指标在不同迭代强度和单能组合的组内比较均有显著统计学差异(P<0.001)。40KeV单能图像的门脉主干CT值均明显高于其他单能图像(P<0.001)。在同一迭代模式下40KeV单能图像的CNR亦明显高于其他单能图像(P<0.001),且主观评分也显著升高P<0.05,其中A3-40KeV单能图像主观评分最高。结论:与120KeV传统成像技术相比,ADMIRE 3迭代强度联合40KeV单能重建能在控制噪声的同时大幅提升门静脉CNR,从而实现门静脉的精准成像。

Objective:To improvethecomputed tomography portal venography by usingthecombination ofvirtual monoenergetic image and iterative reconstruction.Methods:Thirty patients were included in this prospective study.Dual energetic computed tomography portal venography was performed with iterative reconstruction(1,3,5 level),and then the virtual monoenergectic images(40KeV、60KeV、80KeV、100KeV、120KeV、140keV)andclassic polychromatic images(120KeV)were reconstructed by using three groups of iterative data.Finally,twenty-one group of images were acquired from each patient.Average CT value,noise,single-noise ratio(SNR),contrast-noise ratio(CNR)were measured by two radiologists independently,and the subjective scoring was also performed for each group of image.Intraclass correlation coefficient(ICC)was used for consistency evaluation between two group of independent data,and ANOVA was used to compare the indicators.Results:The consistency of measurement between two radiologists was excellent in CT value,CNR,noise and subjective scoring of portal vein with ICC value of 0.95,0.93,0.87,0.80.The objective indicator of image quality had significantly statistical difference among various iterative level and mononenergetic combinations(P>0.001).The CT value of portal vein based on 40KeV monoenergetic image was significantly higher than other monoenergetic(P<0.001).The CNR of 40Kev was also significantly higher than other monoenergetic image in the same iterative level(P<0.001),and the subjective scoring had significantly increased(P<0.05)with the highest score in A3-40KeV monoenergetic image.Conclusion:The combination of ADMIRE 3 iterative reconstruction and 4OKev virtual monoenergetic image was valuable to increase the CNR of portal vein and lower the image noise compared to classic 120KeV polychromatic image,and was helpful for precision imaging of portal vein.