Computed Tomography-Based Coronary Artery Calcium Score Calculation at a Reduced Tube Voltage Utilizing Iterative...

Area of Science:

• Radiology
• Cardiovascular Imaging
• Medical Physics

Background:

• Coronary artery calcium scoring (CACS) is crucial for cardiovascular health assessment.
• Ionizing radiation from computed tomography (CT) poses a concern for CACS.
• Low-dose CT techniques are being explored to mitigate radiation risks.

Purpose of the Study:

• To evaluate the accuracy of iterative reconstruction (IR) and threshold modification for CACS.
• To assess CACS using low tube voltage (80 kVp) coronary CT angiography.
• To compare low-dose CT CACS accuracy against standard protocols.

Main Methods:

• 107 patients underwent dual-voltage (120 kVp and 80 kVp) electrocardiogram-gated CT scans.
• CACS was calculated using standard filtered back projection (FBP) and iterative reconstruction (IR) at 80 kVp.
• Hounsfield unit (HU) thresholds (130, 150, 170, 190) were applied to FBP-reconstructed 80 kVp images.
• Intraclass correlation coefficient (ICC) was used for CACS comparison.

Main Results:

• An 80 kVp protocol reduced effective dose by 64% compared to 120 kVp.
• High-level IR (strength 5) at 80 kVp showed excellent agreement (ICC > 0.9) with standard CACS for scores ≥ 11.
• Modifying HU threshold to 190 in FBP-reconstructed 80 kVp images demonstrated excellent agreement (ICC > 0.9) for scores ≥ 11 and good agreement (ICC = 0.84) for score zero.

Conclusions:

• Iterative reconstruction and density threshold modification enable accurate CACS calculation with low-voltage CT.
• These techniques offer a promising approach to reduce patient radiation exposure during CACS assessment.
• Low-dose CT protocols can maintain diagnostic accuracy for coronary artery calcium imaging.