The clinical value of combining low concentration contrast agent, low tube voltage and iterative reconstruction in CT coronary angiography

ZHANG Hong; MA Yanhe; L(U) Jun; YANG Yapeng; YUAN Wei; SONG Zhenchun

doi:10.19300/j.2017.L4666

Abstract：Objective To evaluation the image quality and radiation dose of combining low kV,low concentration contrast agents and with iterative reconstruction in CT coronary angiography (CTCA).Methods Ninety cases (52 males,38females;age 56.72±14.51 years) were randomly equally divided into groups of A,B and C (30 cases in each group).The contrast agent concentrations of the three groups were:group A 270 mgI/mL,group B 350 mgI/mL,and group C 370 mgI/mL.Group A tube voltage 100 kV,group B and group C tube voltage 120 kV.Tube current were 200～250 mAs.We used 4 points method to evaluate the quality of the images.The CT values at the entrances of left and right coronary arteries and the ascending aortic root were measured.The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the images were calculated to evaluate the image quality objectively.At the same time,the CT dose index,dose length product (DLP) and contrast injection were recorded.The radiation dose and iodine dose were calculated respectively.The analysis of variance with Fisher's Least Significant Difference (LSD) post hoc was used to test the differences in age,DLP,effective dose,signal intensity,noise,CNR,and SNR among the three groups.Gender,subjective scores of image quality were checked byx2.Results There was no significant difference in gender,age,height,body mass,body mass index among the 3 groups (P＞0.05).Total of 1210 (98.94％) coronary artery segments fulfilled diagnostic requirements in 3 groups.Among the 3 groups,the images quality of the coronary arteries showed no significant difference (x2=4.56,P=0.325).There was no significant difference in CT value,SNR and CNR at entrances of left and right coronary arteries and ascending aorta roots among the 3 groups (P＞0.05).The total DLP,effective dose and iodine dose in group A were significantly lower than those in group B and C (P＜0.05),which decreased by 27.58％,27.58％ and 21.27％ respectively compared with group B,and decreased by 28.21％,28.21％ and 24.83％ respectively compared with group C.Conclusions Low kV,low concentration contrast agent and iterative reconstruction in CTCA can obtain comparable image quality to conventional CTCA,while significantly reducing the radiation dose and the administration of iodine dose.