Is beta-blockade necessary to obtain diagnostic image quality at low radiation dose of coronary CT angiography using a 2nd generation 320-row scanner?

Abstract

PURPOSE To evaluate the effect of beta-blockade on coronary computed tomography angiography (CCTA) image quality and radiation dose using a second-generation 320-row scanner.

MATERIAL AND METHODS 200 patients (mean age 60± 3, range 20-86 years;92 females) were included in this prospective study, including 97 patients without beta-blockade and 103 patients with beta-blockade. Target heart rate (HR) in this 2nd group was < 75 bpm, enabling single heartbeat scan, the threshold for a dual heart beat scan was HR < 100 bpm. Image quality in coronary segments ≥ 1.5 mm was evaluated by 2 readers using a four-point scale from grade 1, no artifact to 4, unevaluable. Effects of radiation dose, caliber, HR, arrhythmia, age, BMI, scan length, number of heartbeat/scan, coronary stent, beta-blockade, coronary calcifications, kilovoltage(kV), tube current(mA), and signal to noise ratio(SNR), defined as the ratio between the mean attenuation and the standard deviation in the aorta of on radiation dose (mSv) and image quality were analyzed by using regression analysis. RESULTS: Image quality (grade 1 or 2) was diagnostic in 99,9% and interobserver agreement was good (κ=0,61). Regression analysis of the radiation dose (mean 1,5±0.2 mSv) shows that there is a negative impact of BMI (mean 27,1±2,0kg/m²), arrhythmia during acquisition (n =8), Agatston score, scan length, number of heart beat/scan and the age on the radiation dose, whereas vessel caliber, number of heart beat/scan, age, HR(mean 61,4 beats/min) and SNR negatively impacted the image quality (p-values < 0.05). Beta-blockade impacted neither radiation dose nor image quality (p >0.05).

CONCLUSION Using a second generation 320-row scanner, beta-blockers does not result in a better coronary image quality or lower radiation dose.