双能CT改进的虚拟单能成像重建算法的门静脉图像质量评估

目的 探讨改进的虚拟单能成像重建算法在腹部双能计算机断层扫描（computed tomography，CT）门静脉成像中的应用价值。方法 分析60例研究对象上腹部双能CT增强检查结果，采用配对t检验比较40、50、60、70、80、90和100 keV改进的虚拟单能成像重建算法重建的图像与标准线性融合M_0.5图像（50% 100 kV，50% 140 kV）的门静脉主干的对比噪声比（contrast to noise ratio，CNR），信噪比（signal to noise ratio，SNR）和图像质量评分。结果 门静脉主干40~70 keV改进的虚拟单能成像重建算法重建图像CNR值均比M_0.5图像高，差异有统计学意义（P均<0.05）。与M_0.5图像相比，门静脉主干40~80 keV改进的虚拟单能成像重建算法重建图像的SNR高，差异有统计学意义，（P均<0.05）。门静脉主干的图像质量评分改进的虚拟单能成像重建算法40~70keV重建图像明显优于M_0.5组，差异有统计学意义（P均<0.05）。改进的虚拟单能成像重建算法40 keV重建图像的门静脉主干的CNR和SNR分别是M_0.5组的3.57及1.53倍。结论 改进的虚拟单能成像重建算法是一种很有前景的算法，它能够克服低keV的噪声限制，双能CT门静脉成像40 keV使用改进的虚拟单能成像重建算法重建与M_0.5线性融合相比，图像质量显著提高。

Assessent of portal vein based on a novel virtual monoenergetic algorithm in dualenergy CT

Objective To explore the effect of a novel virtual monoenergetic plus imaging (Mono+) reconstruction algorithm on image quality in portal venography by dual energy CT (DECT) imaging. Methods sixty patients who received abdominal DECT were retrospectively included. Mono+ images were reconstructed at 40,50,60,70, 80, 90 and 100 keV levels. Contrast to noise ratio (CNR),signal to noise ratio (SNR),image quality scores of the main stem of portal veins of 40-100 keV Mono+ images were compared to standard linearly blended M_0.5 images (50% 100 kV, 50% 140 kV)with paired t-test. Results Mono+ DECT series showed a statistically superior CNR at 40,50, 60 and 70 keV compared to M_0.5 images for the main stem of portal vein(P<0.05). SNR of Mono+ images was consistently significantly higher at 40, 50, 60,70 and 80 keV compared to M_0.5 for the main stem of portal vein(P<0.05).The image quality score of Mono+ 40-70 keV series for the main stem of portal vein was significantly better than that of M_0.5 group (P<0.05).The CNR and SNR of Mono+ 40 keV series for the main stem of portal vein were 3.57 times and 1.53 times as much as those of M_0.5 images, respectively.Conclusion Mono+ is a very promising algorithm which is able to overcome noise limitations. Compared to linearly blended images(M_0.5) Mono+ reconstructions at 40 keV levels of portal venography in dual energy CT significantly improved quantitative image quality.