16层螺旋CT成像参数对肺容积和肺密度测量结果影响的研究

目的 研究16层螺旋CT成像参数对肺容积、肺密度评估指标定量分析结果的影响.方法 共筛选50例受检者,根据CT扫描方法的不同分为2组.A组30例,测量在不同重建层厚、重建方式、成像阈值下的全肺容积(total lung volume,V)和平均肺密度(mean lung density,MLD).B组20例40个单侧肺,测量在不同扫描剂量、重建方式、成像阈值下部分肺容积(Vp)和MLD.结果 重建层厚对肺容积和密度测量结果有显著影响:1.25 mm重建层厚所获得的V及MLD较10 mm层厚小(P=0.000);扫描剂量对肺容积测量结果有显著影响,而对MLD无显著影响,低剂量扫描所获得的Vp较常规剂量小(P=0.001);重建方式对肺容积和肺密度测量结果有显著影响,骨重建获得的Vp及MLD较标准重建小(P＜0.05).结论 16层螺旋CT成像参数对肺容积和肺密度测量结果有显著影响,1.25 mm重建层厚、低剂量扫描和标准重建既能满足图像定量分析的需要,又能降低患者所接受的辐射剂量.

Assessment of lung volume and density by 16-slice CT with different imaging parameters

Objective To study the effect of imaging parameters of 16-slice CT on lung volumetry and density measurement. Methods Fifty cases were included and divided into 2 groups. In 30 cases of Group A, total lung volume (V) and mean lung density (MLD) were measured with different slice thickness, reconstruction algorithms and imaging threshold. In 20 cases and 40 unilateral lungs of Group B, partial lung volume (Vp) and MLD were measured with different scan doses, reconstruction algorithms and imaging threshold. Results There were highly significant differences of V and MLD between 1.25 mm and 10 mm slice thickness, the V and MLD measured with 1.25 mm slice thickness were smaller than with 10mm thickness (P=0.000). The effect of scan dose was significant on lung volume analysis but insignificant on MLD, the Vp measured with low dose scan was smaller than with conventional dose (P=0.001). Reconstruction algorithms affected lung volume and density analysis significantly, the Vp and MLD obtained with bone algorithms was smaller than with standard algorithms (P<0.05 ). Conclusion Quantitative analysis of lung volume and density using 16-slice CT is correlated significantly with imaging parameters. Slice thickness of 1.25 mm, low dose scan of 60 mAs and standard algorithms reconstruction can meet the requirements of quantitative analysis and reduce the radiation to patients.