Effects of image reconstruction methods and metal artefact reduction on the analysability and quantification of coronary artery calcium near a pacemaker lead: A phantom study.

INTRODUCTION: Coronary artery calcium (CAC) scoring using non-contrast cardiac CT is widely used for cardiovascular risk stratification. However, metallic devices such as pacemaker leads can produce streak artefacts that hinder reliable CAC assessment. This study evaluated the effects of reconstruction methods and metal artefact reduction (MAR) on CAC quantification adjacent to a pacemaker lead. METHODS: A cardiac CT calibration phantom containing calcified inserts (200-800 mgHA/cm3; diameters 1-5 mm) was scanned using a 320-detector row CT scanner. A pacemaker lead was placed on the phantom surface to simulate metal artefacts. Images were reconstructed using filtered back projection (FBP), hybrid iterative reconstruction (HIR), and deep learning reconstruction (DLR), each with and without MAR. Agatston score, calcium volume, maximum CT value, CT value offset, and relative artefact index (AIr) were evaluated to assess quantitative consistency and artefact severity. RESULTS: MAR substantially improved analysability of calcifications adjacent to the pacemaker lead while maintaining measurement consistency for calcifications analysable under both MAR-off and MAR-on conditions. Without a pacemaker lead, MAR had minimal influence on CAC measurements. In the presence of a lead, MAR markedly reduced streak artefacts and restored analysability of nearby calcifications. CT value offset and AIr were significantly reduced after MAR application for all reconstruction methods. Among the reconstruction methods, DLR showed the lowest CT value offset under both MAR-off and MAR-on conditions and the lowest residual AIr after MAR application. CONCLUSION: MAR improved analysability of CAC adjacent to a pacemaker lead while preserving quantitative consistency for calcifications analysable under both MAR-off and MAR-on conditions. IMPLICATIONS FOR PRACTICE: These findings provide practical guidance for radiographers performing CAC scoring in patients with metallic cardiac devices.