Impact of a New Motion-Correction Algorithm on Image Quality of Low-Dose Coronary CT Angiography in Patients with Insufficient Heart Rate Control

Rationale and Objectives: Prospective electrocardiogram (ECG) triggering allows coronary computed tomography angiography (CCTA) Scanning with low radiation dose but requires heart rates below 63 beats/min. We assessed the impact of a novel vendor-specific motion-correction algorithm on image quality and interpretability of low-dose CCTA acquired despite insufficient heart rate control. Materials and Methods: In 40 patients undergoing CCTA for the assessment of known or suspected coronary artery disease who did not reach the target heart rate below 63 beats/min despite beta-blockade before prospective low-dose scanning, the temporal acquisition window was increased (80 ms additional padding). The new algorithm detects and integrates vessel path and velocity from adjacent cardiac phases for motion correction. Two blinded observers assessed image quality on a 4-point Likert scale (1, nonevaluative; 2, reduced but evaluative; 3, good;,and 4, excellent) and the fraction of interpretable segments (score 2 or more) using motion correction versus standard reconstruction. Results: Image reconstruction with motion correction resulted in an increased median coronary artery image quality score (excellent inter-observer agreement, kappa=0.85) compared to standard reconstruction (3.4 vs. 3.0, P < .001). Consequently, motion-corrected-reconstruction significantly improved the overall interpretability of coronary arteries (from 78% to 88%, P < .001). Estimated mean effective radiation dose was 2.3 +/- 0.8 mSv. Conclusions: A novel, vendor-specific, motion-corrected, reconstruction algorithm improves image quality and interpretability of prospectively ECG-triggered low-dose CCTA despite insufficient heart rate control.