低剂量CT扫描结合自适应统计迭代重建对于体模磨玻璃结节检测的敏感性及清晰度研究

Sensitivity and clarity of low-dose CT scanning combined with adaptive statistical iterative reconstruction for detection of ground glass nodules in phantom

目的:探讨低剂量CT(LDCT)扫描联合自适应统计迭代重建(ASIR)对于体模磨玻璃结节(GGN)检测的敏感性和清晰度,并对相关因素进行分析。方法:通过Revolution CT对放置有6个GGN的仿真胸部体模进行检查,将噪声指数固定为14分,设置不同的前置ASIR权重进行CT扫描。分别在矢状位和冠状位的最大截面测量GNN的长径和短径,观察不同剂量对GGN长短径误差和失圆度的影响;比较不同辐射剂量扫描时对GGN的诊断敏感性;利用4分法观察不同辐射剂量扫描时GGN的清晰度。结果:60%前置ASIR扫描时GGN长短径误差和与失圆度显著高于0%和20%(P<0.05);40%前置ASIR扫描的长短径误差和与失圆度显著低于0%(P<0.05),但是0%和20%以及20%和40%之间相比无显著差异(P>0.05);不同辐射剂量扫描对于GGN的诊断敏感度均为100%;辐射剂量可以影响GGN的清晰度和失真度评分,辐射剂量越低,GGN的清晰度越低,失真度越高(P<0.05)。结论:LDCT对于体模GGN具有很高的诊断敏感性,但是辐射剂量过低会显著降低GGN的清晰度,在临床实践中应注意辐射剂量的调节以呈现更加准确的影像学信息。

Objective:To investigate the sensitivity and clarity of low-dose CT(LDCT)combined with adaptive statistical iterative reconstruction(ASIR)in the detection of ground glass nodules(GGN),and to analyze the related factors.Methods:The simulated chest phantom with 6 GGN were examined by revolution CT.The noise index was fixed to 14 points,and different ASIR weights were set for CT scanning.The long diameter and short diameter of GNN were measured at the maximum section of sagittal and coronal planes respectively,and the effects of different weights and doses on the long diameter error and out of roundness of GNN were observed.The diagnostic sensitivity of different radiation dose scanning for GGN was compared.The clarity of GGN was observed by 4-point method.Results:In 60%ASIR scan,the errors of long and short diameter and out of roundness of GGN were significantly lower than 0%and 20%(P<0.05);The long and short diameter error and out of roundness of 40%ASIR scan were significantly lower than those of 0%(P<0.05),but there was no significant difference between 0%,20%and 20%,40%(P>0.05);The sensitivity of different radiation dose scanning for the diagnosis of GGN was 100%;When the radiation dose difference was more low,the difference was more significant(P<0.05).Conclusion:LDCT has high diagnostic sensitivity for phantom GGN,but low radiation dose will significantly reduce the definition of GGN.In clinical practice,attention should be paid to the adjustment of radiation dose to present more accurate imaging information.