低辐射剂量肝脏CT增强扫描:80kVp结合迭代重建技术的初步研究

Low dose in contrast-enhanced CT scan of liver:80kVp with sinogram affirmed iterative reconstruction technique

目的：探讨80kVp管电压结合迭代重建技术（SAFIRE）在正常体重人群肝脏CT增强扫描中应用的可行性。方法：前瞻性地对身体质量指数（BMI）18~24kg/m2、临床怀疑肝脏疾病的46例患者采用低辐射剂量（80kVp、420mAs）进行CT增强扫描,对比剂注射采用个性化方案。以滤波反投影法（FBP）和5种强度SAFIRE（1~5）方法分别进行图像重建。图像质量的客观评估指标：图像噪声、对比噪声比（CNR）、品质指数（FOM）。图像质量的主观评估：对图像噪声、血管显示、伪影及图像整体质量进行主观评分,并对动脉晚期的期相进行评估。结果：图像质量客观评估结果：SAFIRE-5图像的噪声最小,CNR及FOM值最高,与其余5组图像间差异均有统计学意义（P〈0.05）。图像质量主观评估结果：SAFIRE-5图像的噪声、血管显示情况及硬化伪影的评估结果均优于其它5组,但＂蜡样＂伪影的评分明显低于其它各组,使其图像整体评分受到影响;SAFIRE-3图像的整体评分最高,与其它各组间差异有统计学意义;95.6%（44/46）的动脉晚期图像质量合格。结论：正常体型人群行肝脏CT增强扫描时,使用80kVp结合迭代重建技术及个性化对比剂注射方案,能得到较好的图像质量;此种条件下,建议使用SAFIRE-3进行图像重建。

Objective：To evaluate the feasibility of 80 kVp with sinogram affirmed iterative reconstruction（SAFIRE）technique in liver contrast-enhanced CT scan of normal weight adults.Methods：Forty-six patients with body mass index of18~24kg/m2 and suspected of hepatic diseases were prospectively recruited and then underwent liver contrast-enhanced CT using low dose（80kVp and 420mAs）and personalized contrast injection protocol.Filtered back projection（FBP）and five SAFIRE algorithms were used respectively for image reconstruction,and 6sets of images were obtained for each patient.For objective evaluation,image noise,contrast-to-noise ratio（CNR）and figure of merit（FOM）were measured and calculated.For subjective evaluation,subjective score of image noise,vessel conspicuity,artifacts and overall image quality were assessed,as well as the timing of late arterial phase.Results：For objective analysis,images with SAFIRE-5algorithm showed the least image noise and the highest CNR and FOM,with statistical difference from those of the other 5groups（P〈0.05）.For subjective analysis,images with SAFIRE-5algorithm showed the highest scores of image noise,vessel conspicuity and beam hardening artifacts,and the least score of reconstruction artifacts.As for overall image quality,the image scores of SAFIRE-3were the highest compared with the other 5groups.95.6%（44/46）of the patients could obtain appropriate images in late arterial phase.Conclusion：In liver contrast-enhanced CT,80 kVp with iterative reconstruction technique and personalized contrast media injection protocol can obtain high quality post-contrast images;SAFIRE-3algorithm is recommended for image reconstruction.