Dual-source CT coronary angiography involving injection protocol with iodine load tailored to patient body weight and body mass index: Estimation of optimal contrast material dose

Abstract

Body mass index (BMI) has a positive linear influence on arterial attenuation at coronary CT angiography involving injection protocol with dose linearly tailored to body weight (BW). Excessive contrast material may inadvertently be given in heavier patients when the dose is determined by BW only. To investigate the effect of injection protocol with dose of contrast material (CM) tailored to BW and BMI on coronary arterial attenuation, contrast-to-noise ratio, and image noise at dual-source CT coronary angiography (DSCT-CA). A total of 233 consecutive patients (mean age, 60.2 years) undergoing DSCT-CA were included. Image acquisition protocol was standardized (120 kV, 380 mAs, and retrospective electrocardiograph-triggered DSCT-CA). CM dosage calculation was randomly categorized into groups: a BW group and a BW-BMI group. CM flow rate in both groups was calculated as dosage divided by scan time plus 8 s. Correlations between BW, BMI, and attenuations of ascending aorta (AA) above coronary ostia, left main coronary artery (LM), proximal right coronary artery (RCA), left anterior descending (LAD), and left circumflex artery (LCX), contrast to noise ratio of LM (LMCNR) and RCA (RCACNR), and image noise were evaluated with simple linear regression for two groups individually. In BW group, attenuations of AA and coronary arteries showed positive linear correlations to BW and BMI. In contrast, no relationships were found in BW-BMI group. LMCNR and RCACNR were inversely determined by BW and BMI in both groups. Image noise increased with BW and BMI increasing in two groups. BMI has a positive linear influence on arterial attenuation with fixed iodine per BW. The injection protocol with CM dose tailored to BW and BMI is reasonable during DSCT-CA.