能谱CT对门静脉成像质量影响的研究
The Pilot Study of Energy Spectral CT on the Image Quality of CT Portal Venography
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摘要: 目的: 探讨能谱CT对CT门静脉成像(CT Portal Venography,CTPV)质量的影响。材料与方法: 对45例肝硬化门静脉高压患者行能谱CT扫描,应用能谱分析软件,分别采用混合能量模式(QualityCheck,QC,140kVp)、能量为51keV和70keV的单能模式进行重建,测量并计算三种重建模式CT图像上肝内、外门静脉的对比噪声比(Contrast to Noise Ratio,CNR)及图像噪声(ImageNoise,IN),对不同能量模式的肝内、外门静脉的CNR及IN分别进行比较。结果: 肝内、外门静脉的混合能量及70keV和51keV单能量图像的CNR分别为:3.351.16、4.901.34、8.322.21和6.251.65、8.881.94、13.852.95;肝内、外门静脉的混合能量及70keV和51keV单能量的IN分别为14.062.39、14.962.75、21.813.78和14.282.30、15.121.80、21.793.61;均以51keV单能量为最高,其中肝内、外门静脉的CNR较70keV、混合能量分别提高约60%~70%、120%~150%,而IN分别提高约40%~50%、50%~60%,各组间的差异均有统计学意义;对图像质量的主观评分也有统计意义上的提高。结论: 单能量可以显著提高肝内、外门静脉的显示和CTPV的图像质量,以51keV最佳单能量最显著。Abstract: Objective: To investigate the effect of energy spectral CT on the image quality of CT Portal Venography in cirrhosis patients.Materials and Methods: Fourty-five patients with portal hypertension were underwent GSI(Gemstone spectral imaging) examination.The spectrum analysis was used to select the monochromatic images for obtaining the best contrast-to-noise ratio(CNR) for portal veins.The CNR and image noise of inner and outer liver portal veins at the selected monochromatic level and the conventional polychromatic images were measured and analyzed.Results: The CNR of polychromatic image,monochromatic images at 70 and 51 keV vein were 3.35 ± 1.16,4.90 ± 1.34 and 8.32 ± 2.21 for inner hepatic portal,and 6.25 ± 1.65,8.88 ± 1.94 and 13.85 ± 2.95 for outer hepatic portal respectively.The best quality image was obtained at 51 keV monochromatic level.Conclusion: The image quality of CTPV can be improved by using monochromatic image mode with the most suitable monochromatic level of 51 keV.
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