Coronary CT angiography in obese patients using 3rd generation dual-source CT: effect of body mass index on image quality

Objectives: To evaluate the image quality of coronary CT angiography (CCTA) in obese patients using a 3rd generation, dual-source CT scanner. Methods: We retrospectively evaluated 102 overweight and obese patients who had undergone CCTA. Studies were performed with 3rd generation dual-source CT, prospectively ECG-triggered acquisition at 120 kV, and automated tube current modulation. Advanced modeled iterative reconstruction was used. Patients were divided into three BMI groups: 1)25–29.9 kg/m2; 2)30–39.9 kg/m2; 3) ≥ 40 kg/m2. Vascular attenuation in the coronary arteries was measured. Contrast-to-noise ratio (CNR) was calculated. Image quality was subjectively evaluated using five-point scales. Results: Image quality was considered diagnostic in 97.6 % of examinations. CNR was consistently adequate in all groups but decreased for groups 2 and 3 in comparison to group 1 as well as for group 3 compared to group 2 (p = 0.001, respectively). Subjective image quality was significantly higher in group 1 compared to group 3 (attenuation proximal: 4.8 ± 0.4 vs. 4.4 ± 0.6, p = 0.011; attenuation distal: 4.5 ± 0.7 vs. 4.0 ± 0.8, p = 0.019; noise: 4.7 ± 0.6 vs. 3.8 ± 0.7, p < 0.001). The mean effective dose was 9.5 ± 3.9 mSv for group 1, 11.4 ± 4.7 mSv for group 2 and 14.0 ± 6.4 mSv for group 3. Conclusion: Diagnostic image quality can be routinely obtained at CCTA in obese patients with 3rd generation DSCT at 120 kV. Key Points: • Diagnostic CCTA can be routinely performed in obese patients with 3rdgeneration DSCT. • 120-kV tube voltage allows diagnostic image quality in patients with BMI > 40 kg/m2. • 80-ml contrast medium can be administered without significant decline in vascular attenuation.