| Part 1 The Value of Low-dose Triple-rule-out CT Angiography with Personalized Contrast Injection Scheme on Revolution CTObjective:To evaluate the value of triple-rule-out CT angiography(CTA)with100 kV tube voltage and the personalized contrast injection scheme on the wide-detector Revolution CT.Material and Method:One hundred and twenty patients with emergency chest pain were enrolled in FuJian Medical University Union Hospital from April 2016to August 2017.All of patients underwent triple-rule-out CTA scanning with 100kV tube voltage on GE Revolution CT.For three CTA procedures,the Iterative Reconstruction Technique,called adaptive statistical iterative reconstruction Veo(ASIR-V)was applied,for pulmonary artery and thoracic and abdominal aorta,the magnitude was set at 20%,while for coronary artery was set at 40%.They were divided into four groups(30 cases in each group)based on BMI(Body Mass Index)and contrast injection scheme:Group A had BMI<23 kg/m~2,with injection flow rate of 4ml/s and contrast agent dosage of 1ml/kg;Group B had BMI<23 kg/m~2,with injection flow rate 4ml/s and contrast agent dosage of 0.8ml/kg;Group C had BMI>23 kg/m~2,with injection flow rate 5ml/s and contrast agent dosage of1ml/kg;Group D had BMI>23 kg/m~2,with injection flow rate 5ml/s and contrast agent dosage of 0.8ml/kg.Following the administration of contrast agent,20ml saline was injected.Total amount of contrast agent for each person=0.8 or1.0ml/kg*body weight(kg)+dose used in Test Bolus.The Test Bolus method was adopted to determine the appropriate time point for triple-rule-out CTA scanning:the injection flow rate was 4ml/s or 5ml/s;the contrast agent dosage was 20ml,following injection of 20ml saline;the monitoring level was set at the aortic root level where both pulmonary artery and descending aorta can be displayed;the CT value on these two arteries were then measured;and the time points when CT values of pulmonary artery(t1)and descending aorta(t2)reached peak value were recorded.The time points for scanning pulmonary artery,coronary artery,and thoracic and abdominal aorta were set at t1+2s,t2+2s,t2+2s+3s,respectively.After scanning,we measured CT values on the 9 segments of pulmonary artery,15segments of coronary artery,and 9 segments of thoracic and abdominal aorta.The9 segments of pulmonary artery included the main pulmonary artery,left and right pulmonary trunk,left upper lobe pulmonary artery,left lingual lobe pulmonary artery,left inferior lobe pulmonary artery,right upper lobe pulmonary artery,right middle lobe pulmonary artery and right inferior lobe pulmonary artery;the 15segments of coronary artery included left main coronary artery,proximal,middle and distal segments of left anterior descending branch,1st diagonal branches,2nd diagonal branches,proximal and distal segments of left circumflex branch,obtuse marginal branch,proximal,middle and distal segments of right coronary artery,posterior descending artery,posterior branches of left ventricular,right marginal branch;and the 9 segments of thoracic and abdominal aorta included the ascending aorta,descending aorta,abdominal aortic trunk(right renal artery level)and its main branches(hepatic general artery,splenic artery,superior mesenteric artery,left and right renal artery),and iliac artery bifurcation.Meanwhile,the mean CT values and the corresponding standard deviation(SD)of the subcutaneous fat were also measured at three scanning time points.This SD value was then regarded as the index to indicate the image noise level.In addition,the effective radiation dose were calculated for each patient.Two physicians with more than 5 years of experience in the vascular radiology were responsible for subjective assessment of image quality based on four-point scale.The indexes included CT Value,SD value,CNR,SNR as well as subjective scoring of the pulmonary artery,coronary artery and thoracic and abdominal aorta were evaluated.Results:Between group A and group B,there were no significant differences(P=0.106~0.986)in terms of CT value,SD value,CNR,SNR and the subjective scoring.The same between-group differences were found between Groups C and D(P=0.118~0.956).Conclusions:Our results suggest the feasibility of the triple-rule-out CT angiography(CTA)with 100 kV tube voltage on the wide-detector Revolution CT;meanwhile,the CT images obtained by this scanning program with the personalized contrast injection scheme were qualified for clinical diagnosis.The optimized contrast injection scheme is with the contrast agent dosage of 0.8ml/kg and the distinct injection flow rates(injection flow rate of 4ml/s for the patients with BMI<23 kg/m~2;while injection flow rate of 5ml/s for the patients with BMI>23 kg/m~2).Part 2 The Value of Triple-rule-out CT Angiography with 80 k V Tube Voltage and the Iterative Reconstruction Technique(ASIR-V)in Pulmonary Artery and Thoraco-Abdominal Aorta ImagingObjective: To evaluate the feasibility of Triple-rule-out CT Angiography with 80 k V Tube Voltage and the Iterative Reconstruction Technique(ASIR-V)in Pulmonary Artery and Thoraco-Abdominal Aorta Imaging,by using the personalized contrast injection scheme,in order to decrease the radiation dose.Material and Method: One hundred and twenty patients with emergency chest pain were enrolled in Fu Jian Medical University Union Hospital from April 2016 to April 2018.All of patients underwent triple-rule-out CTA scanning on GE Revolution CT.The tube voltage for both pulmonary artery and thoraco-abdominal aorta CTA was set at 80 k V;while the tube voltage for coronary CTA was set at 100 k V.For three CTA procedures,the Iterative Reconstruction Technique,called adaptive statistical iterative reconstruction Veo(ASIR-V)was applied and the magnitude was set at 40%.Based on the distinct tube voltage during pulmonary artery and thoraco-abdominal Aorta CTA scanning and the personalized contrast injection scheme,all subjects were divided into four groups(30 cases in each group): In Group A,patients had BMI<23 kg /m2 and underwent CT scanning with 80 kv tube voltage,with injection flow rate of 4ml/s and contrast agent dosage of 0.8ml/kg;In Group B,patients had BMI<23 kg /m2 and underwent CT scanning with 100 kv tube voltage,with injection flow rate 4ml/s and contrast agent dosage of 0.8ml/kg;In Group C,patients had BMI>23 kg /m2 and underwent CT scanning with 80 kv tube voltage,with injection flow rate 5ml/s and contrast agent dosage of 0.8ml/kg;In Group D had BMI>23 kg /m2 and underwent CT scanning with 100 kv tube voltage,with injection flow rate 5ml/s and contrast agent dosage of 0.8ml/kg.Following the administration of contrast agent,20 ml saline was injected.Total amount of contrast agent for each person =0.8 or 1.0ml/kg * bodyweight(kg)+ dose used in Test Bolus.The Test Bolus method was adopted to determine the appropriate time point for triple-rule-out CTA scanning: the injection flow rate was 4ml/s or 5ml/s;the contrast agent dosage was 20 ml,following injection of 20 ml saline;the monitoring level was set at the aortic root level where both pulmonary artery and descending aorta can be displayed;the CT value on these two arteries were then measured;and the time points when CT values of pulmonary artery(t1)and descending aorta(t2)reached peak value were recorded.The time points for scanning pulmonary artery,coronary artery,and thoracic and abdominal aorta were set at t1+2s,t2+2s,t2+2s+3s,respectively.After scanning,we measured CT values on the 9 segments of pulmonary artery,15 segments of coronary artery,and 9 segments of thoracic and abdominal aorta.The 9 segments of pulmonary artery included the main pulmonary artery,left and right pulmonary trunk,left upper lobe pulmonary artery,left lingual lobe pulmonary artery,left inferior lobe pulmonary artery,right upper lobe pulmonary artery,right middle lobe pulmonary artery and right inferior lobe pulmonary artery;the 15 segments of coronary artery included left main coronary artery,proximal,middle and distal segments of left anterior descending branch,1st diagonal branches,2nd diagonal branches,proximal and distal segments of left circumflex branch,obtuse marginal branch,proximal,middle and distal segments of right coronary artery,posterior descending artery,posterior branches of left ventricular,right marginal branch;and the 9 segments of thoracic and abdominal aorta included the ascending aorta,descending aorta,abdominal aortic trunk(right renal artery level)and its main branches(hepatic general artery,splenic artery,superior mesenteric artery,left and right renal artery),and iliac artery bifurcation.Meanwhile,the mean CT values and the corresponding standard deviation(SD)of the subcutaneous fat were also measured at three scanning time points.This SD value was then regarded as the index to indicate the image noise level.In addition,the effective radiation dose were calculated for each patient.Two physicians with more than 5 years of experience in the vascular radiology were responsible for subjective assessment of image quality based on four-point scale.The indexes included CT value,SD value,CNR,SNR,DLP,ED as well as subjective scoring of the pulmonary artery,coronary artery and thoracic and abdominal aorta were evaluated.Results:Between group A and group B,there were no significant differencesn in terms of Noise,CNR,SNR and the subjective scoring(P=0.128~0.997).The same between-group differences were found between Groups C and D(P=0.109~0.858).Compared with Group B,the CT values measured in both pulmonary artery and thoraco-abdominal aorta in Group A were significantly increased;while the DLP and ED in Group A significantly decreased(P=0.001~0.039).The same between-group differences in terms of CT value,DLP and ED were found between Groups C and D(P=0.001~0.039).For coronary CTA,no significant differences in terms of above measurements were found between Groups A and B(P=0.213~0.411)and between Groups C and D(P=0.105~0.453).Conclusions: During the Pulmonary Artery and Thoracic-Abdominal Aorta Imaging,the Triple-rule-out CT Angiography with 80 k V Tube Voltage and the ASIR-V technique can produce the vascular images with increased CT value and decrease the radiation dose,based on the personalized contrast agent injection scheme.Meanwhile,this scanning program can produce the qualified coronary images for clinical diagnosis. |
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