高级迭代重建技术在心血管低剂量螺旋CT成像中的动物研究

Advanced iterative reconstruction in low-dose spiral CT scanning of cardiovascular system:An experimental study in animals

目的:探讨高级迭代重建技术(iDose)在心血管低剂量螺旋CT成像中的应用价值。方法:选取家猪10只,本组实验动物均进行以体重为基础的常规X线剂量(A组)及降低X线剂量30%(B组)、50%(C组)、70%(D组)128层前瞻性门控CT扫描,所有数据分别采用滤波反投影(FBP)、iDose-2、iDose-4、iDose-6重建,测量主动脉根部噪声、信噪比(SNR)、对比噪声比(CNR),对图像质量进行评分(5分法评分),3分及以上为图像质量可满足诊断,并对4种重建方法进行比较。结果:A、B、C、D各组内FBP、iDose-2、iDose-4、iDose-6重建后图像的噪声依次降低而SNR、CNR依次升高,且用iDose-6重建与用其余3种方法重建后图像噪声、SNR、CNR的差异均有统计学意义(P<0.05)。用FBP重建,A、B、C3组病例的图像质量均能满足诊断,D组所有病例的图像质量均不能满足诊断;而经iDose重建后所有病例的图像质量均满足诊断,其中用iDose-6重建后除D组6例病例外,其余病例的主观评分均在4分或以上。各组中iDose-6与FBP重建比较的主观评分的差异均有统计学意义(P<0.05)。结论:在心血管CT成像中,应用迭代重建技术(iDose)较FBP可明显降低图像噪声,提高SNR、CNR,提高图像质量,其中iDose-6重建效果最好;在满足诊断的前提下,用iDose-6重建可以降低70%的辐射剂量进行扫描。

Objective. To evaluate the value of advanced iterative reconstruction （iDose） in low- dose spiral CT scanning in cardiovascular system. Methods. Ten pigs were included and were scanned on a256-slice MSCT system utilizing 4 protocols randomly Eroutine dose （group A）, dose reduced by 30% （group B）, 50% （group C）, 70% （group D） respectively2 depending on pig＇s weight. FBP, iDose-2, iDose-4 and iDose-6 were used for reconstruction respectively for all pigs. Noise, SNR, CNR of root of a- orta and were measured. Image quality were graded （scale- 1-5） and compared among the 4 reconstruction methods. Results. For group A, B, C and D, the image noise reduced in turn regarding to FBP, iDose-2, iDose-4 and iDose-6; while for SNR, CNR it was opposite. Besides, iDose-6 reconstruction group showed image noise and SNR, CNR that were significant different from that of the other 3 reconstruction groups （P〈0.05）. With FBP reconstruction, the image qualities of group A, B and C were satisfying for diagno- sis, but for group D, images couldn＇t meet the standard for diagnosis. With iDose reconstruction, images of all groups were satisfying for diagnosis, of which for those reconstructed with iDose-6, scores of all subjects were 4 points or more, except for 6 cases in group D. Significant differences in subjective scores of all groups were found between iDose-6 and FBP reconstruction methods （P〈0.05）. Conclusions. The iter- ative reconstruction （iDose） can reduce image noise, increase SNR, CNR and improve image quality com- pared to FBP in CT scanning of cardiovascular system. IDose-6 enables the lowest noise, the highest SNR, CNR and the best image quality to the greatest extent on equal terms. Acceptable image quality can be obtained with effective dose reduced 70% with iDose-6 in spiral CT scanning in cardiovascular system.