Clinical Research Of Dual Source CT Coronary Angiography Under Double-low-dose For Normal Body Mass Index Patients

Part one Application of dual source coronary CT angiography underlow tube voltage for normal body mass index patientsObjectiveTo assess the image quality of dual source CT coronary angiography under low tubevoltage for normal body mass index patients and to investigate the radiation dose.Material and methodsStudy population: In our hospital,60patients suspected to have coronary arterydiseases and BMI between18.6~25kg/m2of dual source coronary CT angiography,randomly divided into A, B groups, respectively with100KV,80KV tube voltage.CCTA protocol: The CCTA studies were performed using dual-CT(SomatomDefinition Flash).Standard coronary imaging protocols were applied, including0.5mg ofsublingual nitroglycerin was administered to all of the subjects、using high concentrationscontrast material(Omnipaque350mgI/ml)and CM automatic bolus-tracking.The patientswere supine,using Flash spiral model,R-R interval was55%.The scanning range from thetracheal bifurcation1cm to diaphragmatic surface,selecting the head to foot direction.Firstly coronary artery calcium score was scanning,and then the coronary arteryenhancement was scanning.Image analysis: After sanning recording scan length,CT volume dose index and doselength product,calculating the effective radiation dose.To objectively evaluate theattenuation(in HU)and standard deviation(in HU)of the descending thoracic aorta,and theattenuation (in HU) of the three territories (right coronary artery, left anterior descending,left circumflex coronary artery and perivasculartissue of each of the arteries).Thendetermined SNR and CNR of RCA、LAD、LCX.The CT data analysis was performed bytwo radiologists who had more than3years of experience in cardiovascular radiologyrespectively. Statistical analysis: Statistical analyses were performed using SPSS17.0. Continuousvariables are expressed as mean±SD and categoric variables are expressed as frequenciesor percentages.Using descriptive P-P diagram and homogeneity of variance test to analysisthe measurement parameters normality and homogeneity of variance.Weighted Cohen’skappa coefficients (κ-values) were calculated for the assessment of interobserveragreements of image quality.Two independent sample Wilcoxon test was used forcontinuous variables.Coronary artery image quality evaluation results used twoindependent sample X2test,and diagnosed coronary artery segments used X2test tocompare the rate of two independent samples.P values<0.05were considered to bestatistically significant,<0.01were considered to be highly statistically significant.ResultsThere were no statistically significant between the two groups in age, height, weight,heart rate, BMI, CTDIvol and DLP.Group A of ED was0.8mSv, group B was0.41mSv,the difference was statistically significant.In our study,image noise in group A was28±6HU,group B was increased to46±9HU,the difference was statistically significant;theattenuation(in HU) of aorticroot、RCA、LAD and LCX with80KV were significantlyincreased,and the difference were statistically significant.There were no statisticallysignificant between two groups of RCASNR,LADSNR,RCACNR;LCXSNR,LADCNR,LCXCNRbetween two groups were statistically significant.There were significant differences insubjective image quality differences between the two groups,but the two groups can bediagnosied coronary artery segments was no statistical difference.ConclusionFor the normal body mass index patients,dual source coronary CT angiography with80KV tube voltage could diagnose coronary artery disease and could significantly reducethe radiation dose. Part two Application of dual source coronary CT angiography underlow tube voltage and low concentration and volume of contrastmaterial for normal body mass index patientsObjectiveTo assess the image quality of dual source CT coronary angiography under the tubevoltage80KV and low concentration and volume of contrast material for normal bodymass index patients and to investigate the radiation dose and iodine load.Material and methodsStudy population: In our hospital,90patients suspected to have coronary arterydiseases and BMI between18.6~25kg/m2of dual source coronary CTangiography,randomly divided into A、B、C groups,each group had30patients.CCTA protocol: The CCTA studies were performed using dual-CT(SomatomDefinition Flash). Group A used high concentrations of contrast materialiohexol(Omnipaque350mgI/ml),total60ml,the flow rate was5ml/s;Group B used lowconcentrations of contrast material iopromide(Ultravist300mgI/ml),total60ml,the flowrate was5ml/s;Group C used low concentrations of contrast material iopromide(Ultravist300mgI/ml),total45ml,the flow rate was5ml/s.After contrast material was injected,thesame rate of saline were injected50ml in three groups.The CM automatic bolus-trackingwas used.The patients were supine,using Flash spiral model,R-R interval was55%.Thescanning range from the tracheal bifurcation1cm to diaphragmatic surface, selecting thehead to foot direction.Firstly coronary artery calcium score was scanning,and then thecoronary artery enhancement was scanning.The original data wrer used iterativereconstruction such as SAFIRE.Image analysis: After sanning recording scan length,CT volume dose index and doselength product,calculating the effective radiation dose.To objectively evaluate theattenuation(in HU)and standard deviation(in HU)of the descending thoracic aorta,and theattenuation (in HU) of the three territories (right coronary artery, left anterior descending,left circumflex coronary artery and perivasculartissue of each of the arteries).Thendetermined SNR and CNR of RCA、LAD、LCX.The CT data analysis was performed bytwo radiologists who had more than3years of experience in cardiovascular radiologyrespectively. Statistical analysis: Statistical analyses were performed using SPSS17.0.Twoindependent sample Kruskal-Wallis test was used for continuous variables.Objectiveparameters and image quality score of coronary artery between the two two groups wasused compared Bonferroni method.P values<0.05were considered to be statisticallysignificant,<0.01were considered to be highly statistically significant.ResultsThere were no statistically significant between the two groups in age,height,weight,heart rate,BMI,CTDIvol,DLP and ED.The difference of the attenuation of the threeterritories and LCXSNR、LCXCNRwere statistically significant in three groups.Thedifference of the attenuation of the three territories were statistically significant in threegroups,but the difference of image noise and SNR、CNR of three territories were nostatistically significant in group A and B.The difference of the attenuation of the threeterritories、 LCXSNR、LCXCNRwere statistically significant in three groups,but thedifference of image noise and SNR、CNR of RCA and LAD were no statisticallysignificant in group B and C.The comparison between two two groups,there were nostatistically significant in subjective image quality and diagnosied coronary arterysegments.ConclusionFor the normal body mass index patients, dual source CT coronary angiography under80KV tube voltage and low concentration and volume of contrast material could havegood image quality and diagnose coronary artery disease. The radiation dose and iodineload were reduced.