Influence of cardiac hemodynamic parameters on coronary artery opacification with 64-slice computed tomography

Abstract

Influence of cardiac hemodynamic parameters on coronary artery opacification with 64-slice computed tomographyAbstract The purpose of this study was to evaluate the influence of ejection fraction (EF), stroke volume (SV), heart rate, and cardiac output (CO) on coronary artery opacification with 64-slice computed tomography (CT). Sixty patients underwent, retrospectively, electrocardiography-gated 64-slice CT coronary angiography. Left ventricular EF, SV, and CO were calculated with semi-automated software. Attenuation values were measured and contrast-to-noise ratios (CNRs) were calculated in the proximal right coronary artery (RCA) and left main artery (LMA). Mean EF during scanning was 61.5±12.4%, SV was 63.2±15.6 ml, heart rate was 62.5±11.8 beats per minute (bpm), and CO was 3.88±1.06 l/min. There was no significant correlation between the EF and heart rate and the attenuation and CNR in either coronary artery. A significant negative correlation was found in both arteries between SV and attenuation (RCA r=−0.26, P<0.05; LMA r=−0.34, P<0.01) and between SV and CNR (RCA r=−0.26, P<0.05; LMA r=−0.26, P<0.05). Similarly, a significant negative correlation was found between the CO and attenuation (RCA r=−0.42, P<0.05; LMA r=−0.56, P<0.001) and between the CO and CNR (RCA r=−0.39, P<0.05; LMA r=−0.44, P<0.001). The actual hemodynamic status of the patient influences the coronary artery opacification with 64-slice CT, in that vessel opacification decreases as SV and CO increase.

Determinants of vessel contrast in BMI-adapted low dose CT coronary angiography with prospective ECG-triggering

“…CTCA image quality is impaired in patients with high BMI due to increased image noise and decreased coronary attenuation [9][10][11]13]. In the present study we have minimized the impact of BMI on image noise, supporting that the adjustment of tube voltage and current was appropriate.…”

“…First, the amount of contrast material was not BMI-adapted in concordance with a large body of literature [1][2][3][4]6,8], although suggested by a few previous reports [9,10]. However, only the use of a fixed amount of contrast material enabled us to specifically evaluate the influence of BMI on image noise and coronary vessel attenuation.…”

“…According to previous studies, an increase in BMI induces higher image noise [9][10][11] while an increase in CO is associated with a decrease in coronary artery contrast [13]. The latter is most probably caused by more contrast dilution in coronary arteries.…”

“…We performed the calculations of the CNR in the in the left main artery (LMA) as previously reported [13,18]. Briefly, we first determined image noise by placing a region of interest (ROI) (2x2cm) and measured the standard deviation of the attenuation value (in Hounsfield units, HU) in the ascending aorta.…”

“…body mass index (BMI), body surface area (BSA)) [9][10][11] or by contrast bolus dilution depending on cardiac output (CO) [12][13][14]. Coronary calcifications are known to influence image quality by their blooming and beam-hardening artifacts [1,4,7].…”