Coronary Computed Tomography Angiography: Patient-related factors determining image quality using a second-generation 320-slice CT scanner

Abstract

Purpose: To investigate the diagnostic confidence of Coronary Computed Tomography Angiography (CCTA) and the effect of patient-related factors on CCTA image quality using a second-generation 320-slice scanner. Methods and results: 200 consecutive patients (mean age 60 ± 12 years; 109 men) prospectively underwent CCTA. The mean body mass index (BMI) was 27.1 ± 4.9 kg/m2; the median heart rate (HR) was 60.0 (interquartile range (IQR), 53.9–66.1) beats per minute (bpm). The median segment's diameter was 2.8 (IQR, 2.2–3.4) mm. For each coronary segment ≥1.5 mm in diameter, two readers scored: diameter narrowing as b or ≥50%, overall diagnostic confidence and motion-related image quality, with interobserver agreement kappa-values of 0.89, 0.91 and 0.61 respectively. Seventy-nine of the 2505 evaluated segments (3.2%) had non-diagnostic image quality because of coronary calcifications (66/79; 83.5%), stent- (6/79; 7.5%), pacemaker- (2/79; 2.5%) or motionrelated artifacts (5/79; 6.5%). The effect of patient-related factors on motion-related image quality was investigated by multinomial logistic regression in 181 patients with calcium score (IQR, 0–446.5). Increasing coronary diameter was the most improving image quality factor (odds ratio (OR), 1.8637; p b 0.001), marginally followed by lower HR (OR, 0.9547; p b 0.001) and calcium score (OR, 0.9997; p = 0.04). Gender (p = 0.70), age (p = 0.24) and BMI (p = 0.45) did not affect image quality. Conclusion: Using a second-generation 320-slice scanner, CCTA diagnostic confidence is predominantly affected by coronary calcifications, whereas motion-related image quality is non-diagnostic only in exceptional cases and mainly influenced by the coronary diameter. For future developments, our study findings therefore suggest greater requirements concerning spatial resolution and calcium-related artifact removal than concerning temporal resolution, especially to improve diagnostic confidence in patient groups with smaller coronary diameters.