Room: Karl Dean Ballroom B1
Purpose: Robotic C-Arm Cone Beam Computed Tomography (CBCT) systems are playing an increasingly pivotal role in developing image-guided interventional surgical cardiac procedures. Here, we demonstrate a world first 3D gated cardiac CBCT imaging protocol that uses the patientâ€™s electrocardiograph (ECG) signal to adaptively regulate the gantry velocity and projection time interval in real time, enabling personalised imaging acquisition that compensates for cardiac rhythm variations during the scan. In only a single rotation of the gantry, ACROBEAT ensures that a complete set of evenly spaced projections can be acquired from within a desired cardiac phase. Thus, the current need to complete multiple sweeps of the gantry and acquire projections not utilized in the reconstruction process, can be eliminated.
Methods: Simulated in-silico scans using real-time ECG traces from 3 healthy volunteers (average heart rates of 56, 75, 94 bpm respectively) were completed employing the current state-of-the-art protocol along with our adaptive ACROBEAT protocol with varying scan parameters. The XCAT phantom was imaged with each protocol during 60-70% of the cardiac cycle to reconstruct the gated 3D cardiac images. Image metrics of contrast-to-noise ratio and edge response width were used to compare and characterise the quality of the reconstructed images.
Results: For each of the volunteers (56, 75, 94 bpm), the ACROBEAT protocol enabled an increase in contrast-to-noise ratio over the current state-of-the-art protocol of 2-4, 3-4.5 and 4 times between heart/lung and 4-8, 6-8 and 3.5 times between left atrium/surrounding cardiac wall, respectively. Through varying the average angular separation between projections, ACROBEAT permitted a possible 36% reduction in scan time. There was no significant difference in the edge response width between protocols.
Conclusion: ACROBEAT provides the flexibility to trade image quality for total scan time. Further, its scan parameters can be tailored for a variety of different image-guided interventional surgical cardiac procedures.
Funding Support, Disclosures, and Conflict of Interest: This project is supported by a Cancer Australia grant (Priority-driven Collaborative Cancer Research Scheme) number 1123068.