Application Of Revolution CT Double Low Technique And Multi-Parameter Analysis In Head And Neck CT Angiography

Part I: Application value of Revolution CT monochromatic imaging combined with low tube current and individualized dose in head and neck CTAObjective: To explore the application value of Revolution CT monochromatic imaging combined with low tube current and individualized dose in Computed Tomography Angiography(CTA)of head and neck.Methods:A total of 100 patients with suspected head and neck vascular disease who needed to undergo head and neck CTA examination in our hospital from December2019 to February 2021 were prospectively collected and classified into control group A and study group B,50 cases in each group.Group A: 64-slice conventional spiral CT and Group B: Revolution CT monochromatic imaging combined with low-tube current and individualized dose dual-low technique.The general clinical data of the patients were compared and analyzed,including age,gender and body weight,and the image quality of the two groups was evaluated subjectively and objectively.Subjective evaluation included: volume rendering,maximum intensity projection and curved planar reconstruction images were evaluated by 3-point scale;objective evaluation included: 1)Measured two sets of images of the aorta,the carotid bifurcation,M1 segment of middle cerebral artery,with level around vertebral muscles or temporal muscle and CT value of both side body air with level,according to the formula to calculate the corresponding image noise,standard deviation,contrast to noise percentage(CNR),signal noise percentage(SNR);2)Record the dose length product(DLP)of the two groups;3)According to the formula to calculate the effective radiation dose(ED)and iodine load per capita.Results:1.There was no statistical difference in gender,age and body weight between group A and group B(P > 0.05).There was no statistical significance in the subjective score of image noise and image quality between group A and group B(P > 0.05).There were no significant differences in SNR and CNR of aortic arch,carotid artery bifurcation and M1 segment of middle cerebral artery between group A and B(P >0.05).2.The CT values of aortic arch,carotid bifurcation and M1 segment of middlecerebral artery were 431.61±65.53 HU,530.15±83.95 HU and 472.71±90.93 HU respectively in group A,while those of group B were 565.08±80.54 HU,594.38±87.05 HU and 541.56±86.26 HU respectively.The CT value of the control group was lower than that of the study group,and the difference was statistically significant(P< 0.05).The values of DLP and ED in group A were 1327.99± 113.86 m Gy·cm and7.83±0.67 m Sv respectively,while those in group B were 693.88±47.02 m Gy·cm and4.09±0.27 m Sv respectively.DLP and ED in the study group were significantly lower than those in the control group(P < 0.05).The average dosage of iodine contrast agent and iodine load in the study group were lower than those in the control group,and the difference between the two groups was statistically significant(P < 0.05).Conclusion:1.In terms of image quality,Revolution CT double low technology group and conventional 64-row spiral CTA scanning technology group can meet the requirements of clinical diagnosis.2.The radiation dose,iodine contrast agent dosage and iodine load of Revolution CT double low technology group were lower than those in the conventional 64-row spiral CTA scanning group,and the difference was statistically significant(P < 0.05).Part II: Application value of Revolution CT multi-parameter analysis in carotid plaque vulnerability assessmentObjective:To explore the clinical value of multi-parameter analysis on the Revolution CT energy spectrum curve,Effective-Z and Effective-Z diagram in the evaluation of carotid plaque vulnerability.Methods: 350 patients with suspected head and neck vascular disease who underwent Revolution CT head and neck CTA in our hospital from December 2019 to February2021 were retrospectively reviewed and found to have carotid atherosclerotic plaques at the bifurcation of carotid arteries for analysis,46 of whom met the inclusion criteria.In the best single energy image,the CT threshold values of lipid and fiber components in the plaques were calibrated by using multi-parameter analysis such as energy spectrum curve,Effective-Z and Effective-Z diagram,and the difference of composition ratio of lipid and fiber components before and after calibration was compared and analyzed.Results: In the best single energy image,the difference of lipid composition and fiber composition ratio in plaque before and after calibration was statistically significant(P <0.05).Conclusion: In the best single energy image,the CT threshold calibration of lipid and fiber components in plaque can be performed by using multi-parameter analysis such as energy spectrum curve,Effective-Z and Effective-Z diagram,which has a certain guiding significance for the evaluation of carotid plaque vulnerability.