Expanding the Capabilities of Interventional Imaging: Applications of Dual-Energy CBCT for Quantifying Cardiac Iodine Concentrations and Metal Artifact Reduction
Abstract
Purpose
To demonstrate that dual-energy CBCT (DE-CBCT) on angiography systems can deliver material-specific quantitative imaging and metal artifact reduction at the point of intervention.
Methods
DE-CBCT was performed on fixed-room angiography systems (bi-plane and C-arm) by acquiring scans at 70kV and 125kV+Sn. To enable the use of commercial material decomposition software (syngo.via, Siemens Healthineers), the DE-CBCT ratio for iodine was first calibrated using a Gammex multi-energy CT phantom. To investigate cardiac iodine quantification, a CIRS Dynamic Cardiac phantom with iodine inserts of 5 and 10mg/mL was imaged stationary and with heart rate of 60 beats/minute (cardiac motion profile: ±5mm inferior/superior, ±8mm anterior/posterior, and ±6mm lateral). DE-CBCT derived iodine concentrations were measured and compared with known concentrations. To investigate metal artifact reduction (MAR) capabilities of DE-CBCT, a Gammex multi-energy CT phantom with titanium and stainless-steel inserts was imaged. Image quality of virtual monoenergetic images (VMI) was quantified via measurement of the standard deviation of the CBCT-HU over regions-of-interests (ROIs) placed throughout the phantom.
Results
In the CIRS phantom, the average cardiac iodine concentration measured using bi-plane and C-arm DE-CBCT when stationary was 4.4±0.5 mg/mL and 4.3±0.5 mg/mL (5 mg/mL inserts) and 9.7±0.2 mg/mL and 9.8±0.4 mg/mL (10 mg/mL inserts), respectively. With motion, the 5 mg/mL iodine inserts were not identifiable. For the 10 mg/mL inserts with motion, the average cardiac iodine concentration was 6.7±0.9 mg/mL and 5.0±0.7 mg/mL bi-plane and C-arm DE-CBCT, respectively. Noticeable MAR was observed for all systems/scans of the Gammex phantom in VMIs above 100 keV. The standard deviation of CBCT-HU within a central ROI between the metal inserts in 130 keV VMI decreased 46.8% and 65.3% for the bi-plane and C-arm DE-CBCT, respectively, compared to single-energy CBCT at 70kV.
Conclusion
The future clinical utility of DE-CBCT on angiography systems for various applications in interventional radiology was demonstrated.