Low-Dose Coronary CT Angiography in Patients with Atrial Fibrillation: Comparison of Image Quality and Radiation Exposure with Two Different Approaches

Rationale and Objectives: To evaluate image quality, coronary interpretability and radiation exposure of coronary CT angiography (CCTA)performed in patients with atrial fibrillation (AF)with the latest scanner generation, comparing two different technical approaches. A new scanner that combines a 0.23 mm spatial resolution, a new generation of iterative reconstruction, fast gantry rotation time and the intracycle motion-correction algorithm to improve the temporal resolution was recently introduced in the clinical field. Materials and Methods: We enrolled 105 consecutive patients with chronic AF who performed CCTA with a whole-heart coverage high-definition CT scanner (16-cm z-axis coverage with 256 detector rows, 0.28 s gantry rotation time). Five of them were excluded for impaired renal function. Patients were randomized between a double acquisition protocol (50 patients, group 1)or a single acquisition protocol (50 patients, group 2). The image quality, coronary segment interpretability and effective dose (ED)of CCTA were assessed. Results: The mean HR during the scan was 85.6±21 bpm in group 1 vs. 83.7±23 bpm in Group 2, respectively (p < ns). In group 2, overall image quality was high and comparable with that of group 1 (Likert scale =3.2 ± 1.4 vs. 3.3 ± 1.2, p = ns, in group 1 and 2, respectively). Coronary interpretability was high and similar between the two groups (97.5% and 97.1% in group 1 and 2, p = ns, respectively). Mean ED was significantly higher in group 1 than in group 2 (5.3 ± 1.8 mSv vs. 2.7 ± 0.7 mSv, p < 0.001). Conclusion: The novel whole-heart coverage CT scanner allows to perform CCTA with a single-acquisition protocol with high image quality and low radiation exposure in AF patients.