不同级别迭代重建技术在肝脏CT扫描中的应用

Application of different level iterative reconstruction in CT examination of liver

目的评价肝脏CT扫描中不同级别的迭代重建技术(iDose)对图像质量和噪声的影响,探讨获得最佳图像质量、最低噪声的迭代重建级别。方法应用256层CT(Brilliance iCT)对30例患者行肝脏CT扫描。分别采用传统滤过反投影法(FBP)和1～7级迭代重建技术(iDose1～iDose7)对原始数据进行重建,比较不同重建图像在肝脏同一层面的SNR和CNR,并进行统计学分析。由2名影像学诊断医师采用双盲法以4分制对图像质量进行评价。结果 iDose1～iDose7图像的SNR及CNR均高于FBP图像,且CNR随迭代重建级别升高而呈线性升高。iDose2、iDose3、iDose4的SNR值及CNR值差异均无统计学意义,iDose3、iDose4评分值的差异无统计学意义,且二者图像评分最优。结论在肝脏CT扫描中,与常规重建算法FBP比较,采用迭代重建技术(iDose1～iDose7)可明显提高图像质量,降低图像噪声;本组条件下,iDose3、iDose4可以获得最佳图像质量。

Objective To evaluate the image quality and noise using different levels of iterative reconstruction technique （iDose） on liver CT scan, and to explore the best level iterative reconstruction which can provide the best image quality and the lowest noise. Methods A 256-slice CT scanner （Brilliance iCT, Philips Healthcare） was used to perform liver CT examination on 30 patients. The original data of every case were reconstructed using traditional filtered back projection （FBP） and seven different levels of iterative reconstruction techniques （iDose^1-iDose^7 ）, respectively. The SNR and CNR of different levels of reconstruction images at the same layer were analyzed statistically. The image quality was reviewed by two experienced doctors double-blindly using a 4-scale system. Results SNR and CNR values of iDose1-iDose7 images were all higher than those of FBP. There was positive linear correlation between CNR and iterative reconstruction. No significant difference of SNR and CNR values was found among iDose^2 , iDose^3 , iDose^4. There was no significant difference between iDose^3 and iDose^4 scores, and the image quality were the best with iDose^3 and iDose^4 reconstruction. Conclusion On liver CT examination, compared with FBP, the application of iterative reconstruction technique （iDose^-iDose^7） can significantly improve image quality and reduce image noise. Under the condition of this study, using iDose^3 and iDose^4 can get the best image quality.