基于头颅模体的不同重建算法及低剂量扫描对内耳CT成像质量的影响研究

Research on the impact of different reconstruction algorithms and low-dose scanning based on head phantom on the CT imaging quality of inner ear

目的:研究不同重建算法下内耳CT成像质量的影响因素,探索不同重建算法降低内耳CT扫描剂量的可行性和应用价值。方法:基于头颅模体分别采用100、80、70、60、50和40mA固定管电流,行横断位多层螺旋容积高分辨率CT(HRCT),每种管电流进行25例次扫描试验,采用不同重建参数进行内耳CT常用的容积再现技术(VRT)、多平面重建(MPR)和最大密度投影(MIP)3种重建技术重建图像,分析对比不同管电流及重建参数对VRT、MPR、MIP图像软组织、骨质、伪影质量评分的影响。由4名从事影像诊断工作5年以上的影像科医师采用盲法对图像质量按0~3分进行图像质量评分。结果:相同管电流下,VRT、MPR和MIP图像的软组织、骨质、伪影质量评分均随重建间隔的增加而逐渐降低,差异均有统计学意义(F=61.853、49.296、71.280,P<0.05);相同重建间隔参数下VRT、MPR和MIP图像的软组织、骨质、伪影质量评分均随扫描时管电流的降低而逐渐降低,差异均有统计学意义(F=16.346、23.632、21.746,P<0.05)。VRT中图像软组织、骨质和伪影质量评分均与管电流呈正相关(r=0.892、0.907、0.871,P<0.05),与重建间隔呈负相关(r=-0.841、-0.864、-0.866,P<0.05)。结论:内耳CT扫描中,通过减小重建间隔,能有效提升薄层扫描、低剂量扫描的成像质量,进一步降低内耳CT的辐射剂量,在临床上具有应用可行性和临床价值。

Objective:To study the impact factors of computed tomography(CT)imaging quality of inner ear under different reconstruction algorithms,and to explore the feasibility and application value that different reconstruction algorithms reduced the CT scanning dose for inner ear.Methods:Based on the head phantom,fixed tube currents of 100,80,70,60,50,and 40 mA were respectively used to perform high-resolution CT(HRCT)of multi-slice spiral volume at transverse section.Each tube current was used to conduct 25 example number of scanning experiments.Different reconstruction parameters were used to reconstruct images by using three commonly reconstruction techniques for inner ear CT,which included volume rendering technique(VRT),multiple planar reconstruction(MPR)and maximum intensity projection(MIP).The effects of different tube currents and reconstruction parameters on the quality scores of soft tissue,bone,and artifacts in VRT,MPR and MIP images were analyzed and compared.Four physicians used a blind method to score the image quality as a scale of 0-3.Results:Under the same tube current,the quality scores of soft tissue,bone and artifact of VRT,MPR and MIP images gradually decreased with the increasing of reconstruction interval,and the differences were statistically significant(F=61.853,49.296,71.280,P<0.05),respectively.Under the parameters of same reconstruction interval,the quality scores of soft tissue,bone and artifact of VRT,MPR and MIP images gradually decreased with the decreasing of tube current during scanning,and the differences were statistically significant(F=16.346,23.632,21.746,P<0.05),respectively.The quality scores of soft tissue,bone and artifacts of images were positively correlated with tube current(r=0.892,0.907,0.871,P<0.05),and were negatively correlated with reconstruction interval(r=-0.841,-0.864,-0.866,P<0.05),respectively.Conclusion:In CT scanning of inner ear,the decrease of reconstruction interval can effectively improve the imaging qualities of thin-layer and low-dose scans,and further reduce the CT radiation dose of inner ear,which has clinical feasibility and application value.