基于迭代重建技术及低管电压条件下肝脏CT增强图像特点的研究  

Study on the Characteristics of Liver CT Enhanced Examination Base on the Condition of Iterative Reconstruction and Low kVp CT Protocol

作　　者：唐茂文 雷平贵 李方燕 邹迅 焦俊 余晖 TANG Mao-wen;LEI Ping-gui;LI Fang-yan;ZOU Xun;JIAO Jun;YU Hui(School of Medical Imaging,The Affiliated Hospital of Guizhou Medical University,Guiyang 550004,Guizhou Province,China;Department of Radiology,The Affiliated Hospital of Guizhou Medical University,Guiyang 550004,Guizhou Province,China)

机构地区：[1]贵州医科大学医学影像学院,贵州贵阳市550004 [2]贵州医科大学附属医院医学影像科,贵州贵阳市550004

出　　处：《中国CT和MRI杂志》2023年第2期113-116,共4页Chinese Journal of CT and MRI

基　　金：国家自然科学基金(81760312)。

摘　　要：目的 探讨基于原始数据的迭代重建技术在80k Vp条件下肝脏CT增强图像特点。方法 回顾性分析50例上腹部怀疑病变并行腹部CT增强检查的病人资料,及其BMI小于28kg/m2,根据扫描管电压的高低电压组:80k Vp组与120k Vp组(各25例)。以5种不同迭代重建强度(S1、S2、S3、S4、S5)对80k Vp组病人的原始数据图像进行重建,在与传统的滤波反投影法(FBP)重建的图像相比。综合使用客观评价以及主观评价对图像质量进行评估,客观评价指标包括肝脏实质CT值、空气CT值、空气标准差(standard deviation,SD)对比噪声(contrast-to-noise,CNR)、信噪比(signal-to-noise,SNR)。主观评价指标:由2名高级职称的腹组医师对病人的图像进行盲法评估,然后再对两名医师读片一致性进行检验。记录辐射剂量表,最后根据公式算出每例病人的体型特异性剂量估计值(size-specific dose estimate,SSDE)。结果 80k Vp组CTDIvol为(10.18±1.31)m Gy,SSDE为(16.11±2.20)m Gy。120k Vp组的CTDIvol为(14.98±2.62)m Gy,SSDE为(23.02±1.87)m Gy。两者差异均具有统计学意义(P<0.05)。图像质量客观评价:80k Vp-FBP组或者80k Vp-S3(迭代强度S3)组与120k Vp组比较,肝实质CT值差异均具有显著统计学意义(P<0.05);80k Vp-FBP组与80k Vp-S3组比较或者80k Vp-S3组和120k Vp-FBP组比较,CNR和SNR差异均有统计学意义(P<0.05)。主观评价:2名高级职称的腹组医师对所有病人的图像质量评价在满足临床诊断要求条件下,且有良好的一致性(kappa值范围为0.704-0.893)。结论 在80k Vp条件下联合迭代重建技术,并且适当提高管电流,所获得的多期扫描肝脏增强图像符合临床诊断需求,同时降低了病人受到的辐射剂量。Objective To study the characteristics of liver CT enhanced examination at 80kVp with the technique of iterative reconstruction based on original data. Methods The study retrospectively collected 50 patients suspected of having abdominal lesions,two groups [80kVp group(n=25) and 120kVp group(n=25)]were generated according to the tube voltage. The 80kVp liver CT images with filtered back projection(FBP) and different Sinogram-Affirmed Iterative Reconstruction(SAFIRE) strength levels(S1~S5) were obtained by post-process in comparison to 120kVp liver CT enhanced examination with FBP,and image quality was evaluated by quantitatively and qualitatively. For quantitative assessment,the CT value of liver parenchymal,muscle,air,SD of air,contrast-to-noise ratio(CNR) and signal-to-noise ratio(SNR)were measured and calculated in this study. For the qualitative assessment,the whole image quality was evaluated blind by two experienced radiologists,and the inter-observer agreement was also tested. CTDIvol was recorded,and SSDE was also calculated for each patient. Results CTDIvol and SSDE for 80kVp group were(10.18±1.31)mGy and SSDE(16.11±2.20)mGy,respectively;However,CTDIvol and SSDE for 120kVp group were(14.98±2.62)mGy and SSDE(23.02±1.87)mGy,respectively. For quantitative assessment,there was significant statistical difference in CT value of liver parenchymal between two groups,as well as CNR and SNR for 80kVp-FBP vs. 80kVp-S3 or 80kVp-S3 vs. 120kVpFBP. For qualitative assessment,the whole image quality was satisfactory with clinical request for two groups. Conclusion The image quality of liver CT enhanced examination at 80kVp was satisfactory for clinical application by means of increasing the tube current,which has a potential to reduce the radiation dose. Utilizing the technique of iterative reconstruction could improve the image quality of liver CT enhanced imaging.

关 键 词：迭代重建技术 80kVp 肝脏CT增强检查 辐射剂量 图像质量 

分 类 号：R445.3[医药卫生—影像医学与核医学]