| Objective: To explore the clinical application of third-generation dual-source CT for selection of personalized triple?rule?out CTA protocols in patients with chest pain.Materials and Methods: One hundred and fifty consecutive patients who underwent triple?rule?out CTA for chest pain at our hospital with third generation dual source CT between January 2021 and August 2021 were enrolled.The patients were divided into three groups(A,B and C)of 50 cases each according to different scanning protocols.CTA with automatic tube voltage selection(ATVS,CARE k V)and automatic tube current modulation(ATCM)was performed in all groups.Group A used double Turbo Flash scanning mode,requiring a heart rate below 75 beats/min,a flush rhythm,and a two-phase contrast injection protocol;group B used a prospective ECG-gated step scan mode,without heart rate and rhythm control,and a three-phase contrast injection protocol;group C used a single Turbo Flash scanning mode,requiring a heart rate below 75 beats/min,a flush rhythm,and a three-phase contrast injection protocol.The tube voltage was automatically selected by CARE k V based on the patient’s body mass index and the appropriate injection flow rate of contrast was chosen adapted to the determined k V value in all of the three groups.After scanning,the images were transferred to a post-processing workstation and reconstructed including MIP,MPR,CPR,and VR.The mean CT values,noise(SD),signal-to-noise ratio(SNR),and contrast-to-noise ratio(CNR)of the corresponding vessels and muscles were measured and calculated at the level of the ascending aorta,descending aorta,main pulmonary artery,basal trunk of the right and left pulmonary arteries,proximal right coronary artery,distal right coronary artery,proximal left anterior descending branch,distal left anterior descending branch,proximal left circumflex branch,and distal left circumflex branch.Dose length product(DLP)was recorded and the effective radiation dose(ED)to the patient was calculated.Image quality of thoracic aorta and pulmonary artery was subjectively scored by two radiologists according to the presence or absence of motion artifacts,and coronary arteries according to American Heart Association criteria for image quality.The radiation dose,contrast dosage,subjective scores of image quality and objective evaluation indexes(including angiographic CT values,SNR,CNR)were compared among the three groups.P-value<0.05 was considered statistically significant.Result:(1)There was no significant difference in the general data(age,gender,BMI)among the three groups studied(P > 0.05).(2)The mean effective radiation dose(ED)was in the middle(1.78 ± 0.55 m Sv)in group A,the highest(7.14 ± 3.17 m Sv)in group B,and the lowest(0.92 ± 0.32 m Sv)in group C of the three groups.The differences among the three groups and between two groups(A and B,B and C,A and C)in effective radiation dose were all statistically significant(P < 0.05).(3)The mean contrast dose in the three groups was the least in group A(37.32 ± 1.63 ml),the most in group B(75.84 ± 5.39 ml),and the middle in group C(72.66 ± 2.95 ml),and the differences among the three groups and between two groups(A and B,A and C)were statistically significant(P < 0.05),while difference between groups B and C was not statistically significant.(4)Results of the subjective scores of image quality: the mean scores of coronary artery,pulmonary artery and thoracic aorta were: group A(3.66 ±0.72,2.88 ± 0.33);group B(3.68 ± 0.62,2.84 ± 0.42);group C(3.64 ± 0.75,2.90 ±0.30).There was no statistically significant difference between the three groups(P >0.05).(5)Results of objective analysis of image quality: the mean CT values of all vessels in the three groups met the criteria for clinical diagnosis,and the results of statistical analysis were as follows: the differences in mean CT values,SNR and CNR among the three groups in the ascending and descending aorta were statistically significant(P < 0.05),among which the values of groups A and C were significantly higher than that of group B(P < 0.05),while the differences between groups A and C were not statistically significant.The differences in mean CT values,SNR and CNR among the three groups in the main pulmonary artery and the basal trunk of the right and left pulmonary arteries were statistically significant(P < 0.05),with the mean value of group A being significantly higher than that of groups B and C,while the differences between groups B and C were not statistically significant.The differences in mean CT values among the three groups in the proximal segment of the right coronary artery were statistically significant(P < 0.05),and the mean values of groups A and C were significantly higher than that of group B(P < 0.05),whereas the difference between groups A and C was not statistically significant.The differences in SNR and CNR among the three groups in the proximal segment of the right coronary artery were statistically significant(P < 0.05),and the mean value of group A was significantly higher than that of group B(P < 0.05),whereas the differences between groups(A and C,B and C)was not statistically significant.The differences in mean CT values,SNR and CNR among the three groups in the proximal segment of the left anterior descending branch and the proximal segment of the left circumflex branch were statistically significant(P < 0.05),with Group A and C being significantly higher than Group B(P < 0.05),while the differences between Groups(A and C,B and C)were not statistically significant.The differences in mean CT values,SNR and CNR in the distal segment of the right coronary artery,the distal segment of the left anterior descending branch,and the distal segment of the left circumflex branch were not statistically significant among the three groups(P > 0.05).Conclusion: All of the above three personalized triple?rule?out CTA protocols with the third generation dual-source CT can provide images compatible with the clinical requirements.The optimal scanning plan can be selected for patients according to their different conditions,which not only ensures the image quality for diagnostic radiology,but also minimizes the radiation dose and contrast agent dosage for patients,so as to obtain the maximum benefit for them. |
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