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Optimizing coronary CT angiography with spectral dual-layer CT: motion-compensated virtual monoenergetic imaging
E Encinas Vargas1, P M Tetteroo1, C H Kristiansen2
1Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands.
Insights
Motion-compensated reconstruction (MCR) with low virtual monoenergetic images (VMIs) allows for a 50% reduction in contrast media (CM) dose during coronary computed tomography angiography (CCTA) without compromising image quality, even at high heart rates (HRs). This technique optimizes CCTA for better assessment of coronary artery disease (CAD).
Area of Science:
- Medical Imaging
- Radiology
- Cardiovascular Imaging
Background:
- Reduced contrast media (CM) dose in coronary computed tomography angiography (CCTA) presents challenges for assessing coronary artery disease (CAD), especially at elevated heart rates (HRs).
- Motion artifacts and decreased contrast-to-noise ratio (CNR) are significant issues at lower CM doses and higher HRs.
Purpose of the Study:
- To evaluate the effectiveness of a vendor-specific coronary motion-compensated reconstruction (MCR) technique in maintaining image quality during CCTA with reduced CM dose and simulated elevated HRs.
- To assess the impact of MCR on motion area and CNR in virtual monoenergetic images (VMIs) at various simulated HRs and CM doses.
Main Methods:
- A dynamic phantom simulating coronary arteries was imaged using a clinical CCTA protocol with 50% reduced CM dose.
- Coronary motion-compensated reconstruction (MCR) was applied to virtual monoenergetic images (VMIs) reconstructed at different energy levels (40-70 keV).
- Image quality metrics, including motion area and CNR, were compared against a reference standard of conventional CCTA at 100% CM dose.
Main Results:
- At 50% CM dose, elevated velocities (≥30 mm/s) significantly increased motion area (up to 50%) without MCR.
- Without MCR, VMIs showed significant CNR decreases (up to 65%) at velocities ≥30 mm/s.
- The combination of MCR and 40 keV VMI maintained CNR comparable to the reference, irrespective of HR, at 50% CM dose.
Conclusions:
- The combination of MCR and low VMIs (40 keV) enables a 50% reduction in CM dose for CCTA.
- This approach maintains comparable motion area and CNR to conventional CCTA with a full CM dose, even at higher HRs.
- These findings suggest a potential optimization strategy for low CM dose CCTA in patients with elevated HRs, improving CAD assessment.
Abstract:
Reduced contrast media (CM) dose at elevated heart rates (HRs) poses a challenge for coronary artery disease (CAD) assessment. Using a dynamic phantom, we evaluated the performance of a vendor-specific coronary motion-compensated reconstruction (MCR) at various simulated HRs and reduced CM dose in low virtual monoenergetic images (VMIs) from coronary computed tomography angiography (CCTA). A clinical CCTA protocol was used to image a 5-mm artificial coronary artery, filled with 100% (400 Hounsfield units (HU)) and 50% CM dose, using a robotic arm for translation at six velocities (0-50 mm/s, 10 mm/s steps). Conventional images and VMIs (40-70 keV, 10 keV steps) were reconstructed without and with MCR. The study evaluated the MCR influence on motion area and contrast-to-noise ratio (CNR) of the resulting segmented arteries (motion area), with the static conventional reconstructed artery at 100% CM dose as the reference, and non-overlapping 95% confidence intervals with the reference indicating significant differences. At 50% CM dose, motion area increased significantly (up to 50%) at elevated velocities (≥ 30 mm/s) without MCR, while no significant variations were observed with MCR. Additionally, without MCR, VMIs exhibited significant CNR decreases (up to 65%) at velocities ≥ 30 mm/s. Only the combination of MCR and 40 keV VMI achieved CNR comparable to the reference, regardless of HR. The combination of MCR with low VMIs enables 50% CM dose reduction, with similar motion area and CNR when compared to conventional CCTA with 100% CM dose. These parameter settings can potentially be used to optimize low CM dose CCTA at higher HRs.
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