Research On Low-tube-voltage Coronary Computed Tomography With Low Concentration Iodinated Contrast Media By 320-slice CT

Object: To investigate the clinical feasibility of the scan protocol using low-tube-voltage and low concentration iodinated media in 320-slice CT coronary angiography.Method:40 patients(body mass index, 18-26kg/m2) with suspected or known coronary heart disease, were selected from out-patient department from May 1, 2014 to October 1,2015. They were divided into two groups randomly, underwent coronary CT(CCTA) with a 320-MDCT scanner. 20 patients received 120 k Vp with iopromide(350mg I/ml). Another 20 patients received 100 k Vp with iodixanol(270mg I/ml). The two groups received automatic exposure control(AEC). The other scanning parameters were the same. The injection speed of iodinated contrast was equal to 5.0m L/s, using the Sure Start technology. The original images were delivered to Aquilion One V4.74 Vitrea CT postprocessing workstation to reconstruct with two and three dimensional techniques such as MPR, CPR, VR and MIP. Image quality was assessed, using a five-point grading scale by two independent experienced doctors(Deputy Director of Physicians or above) who were unwitting beforehand. Diagnostic, excellent segments and correspondent rates are estimated. The scoring results were compared between group A and group B. The CT attenuation of left coronary artery, image noise, signal-to-noise(SNR), contrast-to-noise ration(CNR), and radiation dose and iodine intake were compared.Results:The effective dose(ED) and iodine intake exited significant differences between the two groups(P<0.05), and the values in group B(2.60±0.52 m Sv) were less than those of group A(12.03±4.19 m Sv). The ED in group B reduces 72.95%, comparing to group A. Accordingly, the amount of iodine in group B reduces 18.29%. Statistically significant difference of image noise and CT values of LCR were found between group A and B(P<0.05), in addition, image noise in group B(73.56±32.34SD) were higher than group A(6.78±29.12SD). However, the SNR, CNR and image quality scores were comparative to both groups(P>0.05).Conclusion :(1) The effective dose of such a scanning project of “270mg I/m L Iodixanol+100k Vp tube voltage” reduced 72.95%,comparing to “350mg I/m L Iopromide+120k Vp tube voltage”. Accordingly, the iodine intake reduced 22.86%.(2) It can acquire images meeting the needs of the clinical diagnosis to use“270mg I/m L Iodixanol+100k Vp tube voltage”.