Application of 256-slice CT coronary angiography with lower radiation dose and lower contrast medium

MA Rong-xi; LI Xiao-hui; SUN Bo-zhang; LI Lin-meng

Abstract：Objective To evaluate the application of 256-slice CT coronary angiography (CTCA) at reduced tube voltage and contrast medium dose .Methods 52 patients suspected with coronary arterial disease underwent 256-slice CTA (tube voltage 80 kV ,contrast medium dose 0 .8 ml/kg) ,the images were post-processed with an iterative reconstruction algo-rithm level of iDose 5(group A);A control group of 50 patients underwent 64-slice CTA (group B) .Two groups were performed with conventional coronary angiography (CCG) .A 4-point scale was used for grading the overall image quality by 2 experienced radiologists .The sensitivity ,specificity ,positive predictive value (PPV) ,negative predictive value (NPV) and accuracy of CTA were evaluated .The radiation dose and contrast medium dose were recorded .Results Diag-nostic CTA images were obtained in all patients .677 diagnostic coronary segments were evaluated in group A ,the sensi-tivity ,specificity ,PPV ,NPV and accuracy were 94 .5% ,97 .4% ,92 .7% ,98 .0% and 96 .6% ,respectively .631 diag-nostic segments were evaluated in group B ,the sensitivity ,specificity ,PPV ,NPV and accuracy were 89 .1% ,96 .4% , 89 .9% ,96 .1% and 94 .5% ,respectively .The mean dose of contrast medium was 56 .8 ml for group A and 82 .2 ml for group B .The mean effective dose was 1 .46 mSv for group A and 8 .37 mSv for group B .Conclusion Combined use of low tube voltage ,low contrast medium dose and iterative reconstruction algorithm is more effective for reducing radiation dose and maintaining image quality in 256-slice CT coronary angiography .