Application of low radiation dosage of coronary CTA in overweight and obese patients

doi:10.3969/j.issn.1002-7386.2015.16.005

Abstract：Objective To investigate the feasibility of reducing coronary CTA radiation dose through decreasing kV in overweight and obesity patients .Methods Sixty overweight patients and 72 obesity patients were selected consecutively .These patients were divided into low-dose group and conventional-dose group, which were denoted as group A 1,group A2,group B1 and group B2,respectively.100kV for group A1,120kV for group A2 and group B1,140kV for group B2.The contrast agent (iohexol, 350mg/ml) was used for enhancement scanning .The image quality of the nine major segments of coronary artery were evaluated by subjective scoring .The enhanced CT values of the four segments including proximal right coronary artery ( RCA-p) , left main artery ( LMA ) , proximal left anterior descending artery ( LADp-) , proximal left circumflex artery (LCX-p) and muscle tissue of chest wall at the same levels were recorded .The enhancement levels above A1,A2,B1,B2, image quality score,image noise,signal to noise ratio (SNR),contrast to noise ratio (CNR), effective radiation dose (ED) were analyzed and compared by means of two independent samples t -test.Results All the patients completed coronary artery examination,and the image quality met the diagnostic requirement .There were no significant differences in image score of 9 coronary segments ,enhancement levels , image noise and SNR of the four coronary segments , however , there were significant differences between CNR and ED.The ED in group A1 and A2 were (8.47 ±0.76) mSv and (12.22 ±2.41) mSv, respectively,which in group B1 and B2 were (13.69 ±1.142) mSv and (20.31 ±1.36) mSv,respectively.Conclusion The coronary artery examination for overweight and obesity patients can reduce kV to decrease effective radiation dosage and decrease coronary image CNR .