Impact Of Different KeV Images In Dual-energy Spectral CT On The Quantifications For Male Emphysema Patients

Object: 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 by using energy spectrum scanning mode,GSI(gemstone spectral imaging)view and Shaded Surface Lung software.Method: Dual-energy spectral CT scanning was performed on 40 male patients with emphysema.Create a set of data from the 50-80 KeV every 5KeV using GSI view software,a total of 7 groups,and 5mm(thick layer)MO NO data was reconstructed in 0.625mm(thin layer)MONO data.Then calculate the total volume of the lungs,average density and EI index by using the Shaded surface lung software.The total volume,mean density and EI index of patients under different reconstruction thickness and in images of different photon energies(KeV)were measured and compared.The statistical software version is SPSS22.0.P< 0.05 was considered to be statistically significant.Result: 1)There was no significant difference in total volume and mean CT value in different photon energies(unit:volume(ml),CT ?(Hu)volume P=0.655>0.05;mean CT value P =0.998>0.05),but the total volume measurement was more stable for photon energy greater than 60 KeV.Total volume in each group of 50-80 KeV was 4329.9±993.9,4507.0±1057.8,4719.8±1170.2,4776.4±1206.4,4780.1±1207.6,4780.1±1207.6,4779.9±1200.8,4766.6±1185.0,4665.7±1143.4;The average CT value in each group of 50-80 KeV was-855.4±31.2,-855.9±32.9,-852.4±36.7,-850.8±38.2,-852.1±38.0,-853.2±38.0,-854.2±37.8.2)There were differences in the EI index under different KeVs(P<0.05).EI index measurement at low KeV exhibited a large error,and the measurement was more stability with photon energies greater than 60 KeV.EI-950 index in each group of 50-80 KeVs is 0.205±0.096,0.180±0.095,0.133±0.096,0.093±0.0172,0.113±0.095,0.118±0.096,0.124±0.098.3)There was no significant difference in the total volume measurement between thin and thick layer CT.Mean value of the total volume of thin layers is 4495.0±1309.0,The mean value of the total volume of the thick layer is 4515.5±1361.2.4)There were differences in both average CT value and EI index in CT scanning with different thickness.(CT value P=0.023<0.05;EI index P=0.03<0.05).The CT value increased about 20 HU in thick layer CT compared with the thin layer CT.The average CT value of the thin layer is-841.2±36.9,the average CT value of the thick layer is-821.2±39.1.The EI-910 index of thin layer was 0.227 ± 0.155,and the EI-910 index was 0.136± 0.128.Conclusion:Different KeVs and image thickness have influence on the quantitative determination of emphysema.