Clinical Study Of Low Tube Voltage And Low Concentration Iodine Contrast Medium For Cervicocranial CTA Using Third-generation Dual-source CT Scanner

Objective: To explore the clinical value of low tube voltage and low concentration iodine contrast medium for cervicocranial computed tomography angiography(CTA)by using the third-generation dual source CT scanner.Materials and Methods: This study included 400 patients who underwent cervicocranial CTA examination prospectively by using the third-generation dual source CT scanner from August 2019 to August 2020.According to different scanning modes(tube voltage)and different concentrations of iodine contrast medium,the patients were randomly divided into A,B,C and D groups,with 100 patients in each group.Contrast medium with iodine concentration of 350 mg I/ml was used in both group A and B,while contrast medium with iodine concentration of 300 mg I/ml was used in group C and group D.Group A and C underwent dual energy scanning with 80/sn150 k V tube voltage,while group B and D performed conventional scanning with tube voltage of 80 k V.After the scanning,the images were transmitted to the post-processing workstation,and MIP,MPR and VR were used for reconstruction.In the aortic arch,the right common carotid artery bifurcation,the right internal carotid artery,basilar artery and the right middle cerebral artery,the average CT value,signal-to-noise ratio(SNR),contrast to noise ratio(CNR)and noise(SD)were measured and calculated in the corresponding blood vessels and muscles.At the same time,two radiologists used five-point scale to grade the images according to image quality.Mann–Whitney U test was statistically used to analyze the difference in subjective scores of image quality between two groups.Objective image evaluation parameters,including radiation dose,vascular CT value,SNR,CNR,SD and total iodine,were compared between the two groups by using two independent samples T-test;The Kappa test was used to assess the consistency of image quality scores between two radiologists.Results: There was no statistically significant difference in the general data of patients of the four groups(P > 0.05).When using the same scanning mode(dual energy scanning with tube voltage of 80/sn150 k V or conventional scanning with tube voltage of 80 k V),there was significant difference in the total amount of iodine between the groups after injection of 350 mg I/ml(group A and B)and300mg I/ml(group C and D)contrast medium(P < 0.05),but no statistical difference was found in image quality evaluation results(including objective evaluation and subjective score)(P > 0.05).When a low concentration of iodine contrast medium(300mg I/ml)was used,SD of group C(dual energy scanning with tube voltage of 80 / sn150 k V)and group D(conventional scans with tube voltage of 80 k V)in the basilar artery and aorta of had statistically differences(P < 0.05),the SD and image quality in the remaining locations of subjective or objective evaluation parameters had no statistical difference(P > 0.05),however the radiation dose of group D was significantly less than that of group C(P < 0.05).Conclusion: Compared with the higher concentration(350mg I/ml)iodine contrast medium group,the image quality of cervicocranial CTA obtained with the lower concentration(300mg I/ml)iodine contrast medium can meet the requirements of clinical diagnosis;compared with the dual-energy group with a tube voltage of80/sn150 k V,the radiation dose received by the patients in the conventional scanning group with low tube voltage(80k V)was significantly reduced,and the image quality of the two groups was similar.