Abstract： Objective To investigate image quality and radiation dose of prospective ECG-gated coronary combined with carotid and cerebrovascular angiography and compare it with common coronary CTA and carotid-cerebrovascular CTA at a 256-slice spiral CT.Methods Fifty-seven patients were included in the study.The data was analyzed retrospectively and divided into 3 groups.Group 1 underwent coronary combined with carotid CTA ( n =17 ),which included a wide range of prospective ECG-gated coronary,carotid and cerebral vascular one-stop angiography.Group 2 underwent coronary CTA ( n =20),which was routine prospective ECG-gated coronary angiography.Group 3 underwent routine carotid and cerebrovascular CTA (n =20).Mean CT image attenuation and image noise were measured in the ascending aorta root,proximal parts of the bilateral common carotid artery and vertebral artery,and in the internal carotid artery at sellae level in the axial plane.Coronary artery image quality was rated using a four-point ordinal scale and carotid cerebral vascular image quality was rated using a three-point ordinal scale.Radiation dose were calculated.Mean CT image attenuation,image noise and radiation dose were compared among the 3 groups using t test.Using Mann-Whitney U,the coronary artery imaging quality was compared between group 1 and 2,and image quality of cerebral vessels was compared between group 1 and 3.Results Mean CT image attenuation [ (427 ±50) HU in group 1 and (426 ±86) HU in group 2] and image noise of the ascending aorta root [ (30 ± 9) HU in group 1 and (31 ± 9) HU in group 2 ] showed no statistical difference between group 1 and 2 (t =0.058,-0.325,P ＞0.05).There were no non-diagnosis coronary segments in group 1 and 2.And coronary segments with excellent or good image quality reached 98.1％ (202/206) in group 1 and 99.6％ ( 244/245 ) in group 2.It showed no significant difference between group 1 and 2 ( Z =-0.572,P ＞ 0.05 ).There were significant differences of mean CT image attenuation in the common carotid artery between group 1 [ ( 474 ± 70 ) HU ] and group 3 [ ( 348 ± 81 ) HU ],and in the vertebral artery between group 1 [(447 ±83)HU] and group 3 [(328 +66) HU] (t =5.043,4.869,P＜0.05).However,there was no significant difference of mean CT image attenuation in the internal carotid artery [ (370 ± 92) HU in group 1 and ( 367 ± 97 ) HU in group 3 ] ( t =0.111,P ＞ 0.05 ).There was a significant difference of image quality scores of carotid and cerebrovascular arteries between group 1 and 3 (Z =- 3.306,P ＜ 0.05 ).Effective radiation dose of groups 1,2,3 were ( 7.0 ± 0.8 ),( 3.1 ± 0.4 ) and (5.0 ± 0.3) mSv respectively.Conclusion The prospective ECG-gated coronary combined with carotid and cerebrovascular angiography is able to obtain diagnostic image quality of coronary,carotid and cerebral vascular at the 256-slice spiral CT.It is a simple,fast,noninvasive way to assess coronary and carotid cerebrovascular arteries,with advantages of less contrast medium and low radiation dose.