The Application Value Of Low Dose Contrast Media In CT Pulmonary Angiography With Gemstone Energy Spectrum CT

Objective:To investigate the application value of low dose contrast agent gemstone energy spectrum CT GSI scanning in CTPA.Methods:CTPA examination was performed on 40 patients with suspected acute pulmonary embolism.According to the registration number,they were randomly divided into two groups,and according to the amount of contrast agent and the scanning method,they were divided into groups A and B.In group A,conventional scanning method was used,and the dosage of contrast agent was 80ml(350mg/ml).Group B was scanned by GSI,and the dosage of contrast agent was 30ml(350mg/ml).The single factor anova was used to select the best single energy level for the energy spectrum images of group B.Objective and subjective evaluation was made on the images obtained from the conventional group and the energy spectrum optimal single energy group.Objective evaluation included CT values of pulmonary artery segments,image background noise,SNR,CNR,CTDIvol,DLP and ED of the two groups.The obtained data were compared by t test of independent samples.Mann-WhitneyU nonparametric rank sum test was used to compare the difference of subjective score between the two groups of images.Results:The optimal single energy image level of the energy spectrum sequence of pulmonary artery is about 65 keV.Compared with the conventional group,CT values,SNR and CNR of pulmonary artery in the energy spectrum group were significantly different(P<0.05).The CT values of pulmonary artery in group B were higher than those in group A.The noise of group B was lower than that of group A,with no significant difference(P = 0.065).The radiation dose CTDIvol,DLP and ED energy spectrum groups were lower than The conventional group,with statistically significant differences(P<0.05).The subjective scores of the two groups could meet the requirements of clinical diagnosis,and the difference was not statistically significant(P>0.05).Conclusion:Low dose contrast agent in gemstone spectrum CT pulmonary artery imaging,can obtain better image quality to meet the diagnostic requirements,can effectively reduce the incidence of contrast agent nephropathy.