能谱CT不同千电子伏特对男性肺气肿患者定量测定的影响分析

Impact of different kiloelectron volt images in dual-energy spectral CT on the quantifications for male emphysema patients

目的讨论能谱CT扫描方式下,不同千电子伏特(ke V)下对男性肺气肿患者总体积、平均CT值、气肿指数测量时的影响。方法对确诊的40例男性肺气肿患者行能谱扫描。评价不同ke V下,不同重建层厚下全肺总体积,平均密度,气肿指数差异是否有统计学意义。结果 (1)不同ke V下肺气肿总体积、平均CT值差异无统计学意义(体积P=0.655>0.05;平均CT值P=0.998>0.05)。但>60 ke V时总体积测量更稳定。(2)不同ke V下气肿指数差异有统计学意义(P<0.01)。低ke V测量气肿指数会产生较大误差,>60 ke V时测量稳定。(3)薄层与厚层CT对体积测量差异无统计学意义(P=0.946>0.05)。(4)不同层厚对平均CT值及气肿指数测量差异有统计学意义(CT值P=0.023<0.05;气肿指数P=0.03<0.05)。厚层CT较薄层CT升高20 Hu左右。结论不同ke V及层厚对肺气肿定量测定有影响。

Objective To evaluate the influence of different keV images in dual-energy spectral CT on the total volume, average density and EI index of the male patients with pulmonary emphysema. Methods Dual-energy spectral CT scanning was performed on 40 male patients with emphysema. The totalvolume, mean density and El index of patients under different reconstruction thickness and in images of different photon energies （keV） were measured and compared. Results ① There was no significant difference in total volume and mean CT value indifferent photon energies （volume P=0.655; mean CT value P=0.998）, but the total volume measurement was more stable for photon energy greater than 60 keV. ② Therewere differences in the EI index under different keVs （P〈0.01）. EI index measurement at low keV exhibited a large error, and the measurement was more stability with photon energies greater than 60 keV. ③ There was no significant difference in the total volume measurement between thin and thick layer CT （P=0.946）. ④ There were differences in both average CT value and EI index in CT scanning with different thickness.the CT value increased about 20 Hu in thick layer CT compared with the thin layer CT. Conclusion Different keVs and image thickness have influence on the quantitative determination of emphysema.