The influence of body mass index and gender on coronary arterial attenuation with fixed iodine load per body weight at dual-source CT coronary angiography

Abstract

Background Most of current coronary CT angiography protocols are not adapted to body weight (BW) or cardiac output and no literature about influence of gender on coronary attenuation are reported with administration of a fixed iodine load per BW. Purpose To determine the influence of body mass index (BMI) and gender on coronary arterial attenuation if contrast material dose is linearly adjusted to a patient's BW at dual-source CT coronary angiography (DSCT-CA). Material and Methods A total of 207 consecutive patients (mean age 60.6 years) undergoing DSCT-CA were included. Contrast material (370 mg I/mL) dose calculation was randomly categorized into two groups (Group1: 1.10 mL/kg for men and women; Group 2: men 1.10 mL/kg, women 0.99 mL/kg) and flow rate was calculated as dose was divided by scan time plus 8 s. Mean arterial attenuations between men and women were compared with respect to attenuations of ascending aorta (AA) above coronary ostia, left main coronary artery (LM), proximal segments of right coronary artery (RCA), left anterior descending (LAD), and left circumflex artery (LCX) in two groups, respectively. Attenuations of coronary arteries were correlated with BW and BMI with simple linear regression. Results The mean attenuations of AA, LM, RCA, LAD, and LCX were 407.8 ± 53.6 HU, 412.6 ± 55.4 HU, 411.4 ± 64.3 HU, 399.1 ± 56.7 HU, and 399.1 ± 60.2 HU, respectively, and there were no significant differences between men and women in group 1 (AA, P = 0.571; LM, P = 0.670; RCA, P = 0.737; LAD, P = 0.439, and LCX, P = 0.888). In group 2, the mean attenuations of AA, LM, RCA, LAD, and LCX in men were significantly higher than those in women (AA, P = 0.008; LM, P = 0.025; RCA, P = 0.017; LAD, P = 0.015, and LCX, P = 0.002). Positive linear regression between BW and attenuations of AA (R2 = 0.047, P = 0.02), LM (R2 = 0.036, P = 0.04), RCA (R2 = 0.080, P < 0.01), LAD (R2 = 0.078, P < 0.01), and LCX (R2 = 0.033, P = 0.05) was found in group 1, suggesting that attenuations of coronary arteries increased in heavier patients. Similarly, there was positive linear regression between BMI and attenuations of AA (R2 = 0.117, P < 0.01), LM (R2 = 0.090, P < 0.01), RCA (R2 = 0.138, P < 0.01), LAD (R2 = 0.111, P < 0.01), and LCX (R2 = 0.078, P < 0.01). Conclusion Men and women have similar coronary attenuations with a fixed iodine load per BW. BMI has a positive linear influence on arterial attenuation at DSCT-CA involving injection protocol with dose linearly tailored to BW. Excessive contrast material may inadvertently be given in heavier patients when the dose is determined by BW only. Contrast material dose may need to be tailored individually by BW and BMI.