Abstract：Objective To investigate the effect of iodine delivery rate (IDR) and contrast agent dose on the image quality of carotid
artery CT angiography (CTA) imaging in obese patients, so as to guide the optimal use of contrast agents. Methods Eighty patients
with clinically suspected carotid stenosis or carotid plaques were randomly divided into 4 groups (20 patients each group) who
underwent carotid artery CTA examination. Group A: 50 mL dosage of lopamiro 300 mgI/mL, 5 mL/s injection velocity, IDR
1.5 gI/s. Group B: 50 mL dosage of lopamiro 300 mgI/mL, 4.5 mL/s injection velocity, IDR 1.35 gI/s. Group C: 40 mL dosage of lopamiro
370 mgI/mL, 4.5 mL/s injection velocity, IDR 1.67 gI/s. Group D: 30 mL dosage of lopamiro 370 mgI/mL, 4.5 mL/s injection velocity,
IDR 1.67 gI/s. The CT values of the same carotid artery in four groups were analyzed and compared, the contrast-to-noise ratio (CNR)
and noise-signal ratio (SNR) were compared, and the image quality was evaluated. Results There was no significant differences in CT
value of carotid artery at the same place of group A, B and C. The CT values of the carotid artery in the first three groups were significantly
different with group D. The four groups’ CNR and SNR were (19.25±6.37) and (23.10±7.15); (21.19±5.90) and (25.38±6.40);
(21.61±7.60) and (25.87±7.50); (13.39±3.50) and (17.78±3.96), respectively. There was no significant difference of CNR and SNR
among the first three groups, but they were statistically significant with group D. There were no significant differences of quality of the
image reconstruction among the first groups, while they were statistically different with group D, but the image quality of group D could
still meet the diagnostic needs. Conclusion For obese subjects, increasing the injection speed can raise IDR and guarantee the quality of
the image, but it also will increase the risk of injection. In this study, a high concentration of contrast is used to improve IDR when the total
iodine is unchanged. It will not only affect the image quality, but also decrease the injection speed and reduce the risk of contrast media.
