Force CT单能量成像技术在提高基底动脉图像质量中的应用价值

Application value of Force CT monochromatic imaging in improving the quality of basilar artery imaging

目的探讨Force CT虚拟单能量成像技术在提高基底动脉图像质量的应用价值。方法本研究前瞻性纳入2020年1月至8月在Force CT行头颈CT血管造影术(CTA)检查的患者60例,管电压采用80/sn150 kV,碘浓度为300 mgI/ml的碘帕醇。扫描结束后将图像传至后处理工作站上,获得线性120 kV的平均加权图像;以5~10 keV为增量,从50~90 keV重建出虚拟单能量图像(virtual monochromatic images,VMI)。在基底动脉水平测量并计算相应血管和背景组织的平均CT值、信噪比(SNR)、对比噪声比(CNR)和噪声(SD)。同时,两个医师采用5分制对图像质量进行主观评分。采用配对样本t检验分别比较平均加权图像和不同keV图像2组间客观图像评价指标,kappa检验用于评估两个放射科医师之间图像质量评分的一致性。结果基底动脉平均CT值、SD和伪影指数随着keV增大而降低,其平均加权图像与60~75 keV的SNR和CNR的差异有统计学意义(P<0.05),以65 keV达到最高,其他keV差异无统计学意义(P>0.05)。VMI图像的主观评分高于融合图像,两者差异有统计学意义(P<0.05)。结论Force CT虚拟单能量技术可以降低射线硬化伪影,在实际应用中选择60~75 keV的单能量水平可以提高基底动脉的图像质量。

Objective To investigate the application value of force CT monochromatic imaging in improving the quality of basilar artery imaging.Methods Sixty patients undergoing head and neck computed tomography between January and August 2020 were prospectively enrolled in this study,the tubular voltage was 80/sn150 kV with iodide concentration of 300 mg I/ml iodopol.After the scan was finished,images were transferred to the postprocessing workstation,and average weighted images of linear 120 kV were acquired;the virtual monochromatic images were reconstructed from 50~90 keV at an incremental volume of 5~10 keV.The average CT value,signal-to-noise ratio(SNR),contrast-noise ratio(CNR),and noise(SD)were measured at the basal artery level and calculated for the corresponding vessels and background tissues.At the same time,both observers used a 5-point scale to subjectively rate image quality.Objective image evaluation between the two groups using paired-sample t-test comparison of average weighted images and different keV images,respectively.The kappa test was used to assess the consistency of image quality scores between the two radiologists.Results Mean basal artery computed tomography,SD,and pseudoindex decreased with the increase in keV,the mean weighted images were significantly different from those obtained with 60~75 kV SNR and CNR(P<0.05).The highest keV was 65 keV,with no significant difference in other keVs(P>0.05).The subjective score of the VMI image was higher than that of the fusion image,and the difference was statistically significant(P<0.05).Conclusion Virtual monochromatic CT with Force dual-energy CT reduces the artifact of radiation hardening,selection of a single energy level of 60~75 keV can improve image quality of the basilar artery in practical applications.