Citation: Vecsey-Nagy, M.; Jokkel, Z.; Jermendy, Á.L.; Nagy, M.; Boussoussou, M.; Vattay, B.; Kolossváry, M.; Csobay-Novák, C.; Amin-Spector, S.; Merkely, B.; et al. The Impact of Novel Reconstruction Algorithms on Calcium Scoring: Results on a Dedicated Cardiac CT Scanner. Diagnostics 2023, 13, 789. https://doi.org/10.3390/ diagnostics13040789 Academic Editor: Andrea D. Annoni Received: 27 December 2022 Revised: 27 January 2023 Accepted: 10 February 2023 Published: 20 February 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). diagnostics Article The Impact of Novel Reconstruction Algorithms on Calcium Scoring: Results on a Dedicated Cardiac CT Scanner Milán Vecsey-Nagy 1, * ,† , Zsófia Jokkel 1,† , Ádám Levente Jermendy 1 , Martin Nagy 1 , Melinda Boussoussou 1 , Borbála Vattay 1 ,Márton Kolossváry 2,3 , Csaba Csobay-Novák 1 , Sigal Amin-Spector 4 ,Béla Merkely 1 and Bálint Szilveszter 1 1 Heart and Vascular Center, Semmelweis University, 68. Varosmajor Street, 1122 Budapest, Hungary 2 Gottsegen National Cardiovascular Center, 29. Haller Street, 1096 Budapest, Hungary 3 Physiological Controls Research Center, University Research and Innovation Center, Óbuda University, 96/b Bécsi út, 1034 Budapest, Hungary 4 Arineta Ltd., 15. Khalamish Street, P.O. Box 3057, Caesarea 3088900, Israel * Correspondence: vecsey_nagy.milan@med.semmelweis-univ.hu † These authors contributed equally to this work. Abstract: Contemporary reconstruction algorithms yield the potential of reducing radiation expo- sure by denoising coronary computed tomography angiography (CCTA) datasets. We aimed to assess the reliability of coronary artery calcium score (CACS) measurements with an advanced adaptive statistical iterative reconstruction (ASIR-CV) and model-based adaptive filter (MBAF2) designed for a dedicated cardiac CT scanner by comparing them to the gold-standard filtered back projection (FBP) calculations. We analyzed non-contrast coronary CT images of 404 consecutive patients undergoing clinically indicated CCTA. CACS and total calcium volume were quantified and compared on three reconstructions (FBP, ASIR-CV, and MBAF2+ASIR-CV). Patients were classified into risk categories based on CACS and the rate of reclassification was assessed. Patients were categorized into the following groups based on FBP reconstructions: 172 zero CACS, 38 minimal (1–10), 87 mild (11–100), 57 moderate (101–400), and 50 severe (400<). Overall, 19/404 (4.7%) pa- tients were reclassified into a lower-risk group with MBAF2+ASIR-CV, while 8 additional patients (27/404, 6.7%) shifted downward when applying stand-alone ASIR-CV. The total calcium volume with FBP was 7.0 (0.0–133.25) mm 3 , 4.0 (0.0–103.5) mm 3 using ASIR-CV, and 5.0 (0.0–118.5) mm 3 with MBAF2+ASIR-CV (all comparisons p < 0.001). The concomitant use of ASIR-CV and MBAF2 may allow the reduction of noise levels while maintaining similar CACS values as FBP measurements. Keywords: coronary artery disease; coronary artery calcium score; image reconstruction; cardiovascular risk 1. Introduction Coronary artery disease (CAD) is responsible for approximately half of cardiovascular disease (CVD) associated deaths; meanwhile, CVDs remain the leading cause of morbidity and mortality worldwide [1,2]. Although there are several pharmacological methods and lifestyle options available for primary and secondary prevention of CVDs, identifying patients who could benefit most from early initiation of therapy remains a significant challenge [3]. Traditional risk models incorporating markers such as age and sex provide limited accuracy at an individual level to guide patient management [4]. Therefore, further methods are needed for the prediction of CV risk in order to provide precise early detection and risk stratification for patients [5]. Coronary artery calcium score (CACS) is a robust non-invasive diagnostic marker for the quantification of calcified coronary atherosclerotic burden [6]. CACS can be measured using non-contrast cardiac CT scans with relatively low radiation exposure; nevertheless, it provides valuable prognostic information regarding future cardiovascular events in both symptomatic and asymptomatic patients [7]. Several population-based studies have Diagnostics 2023, 13, 789. https://doi.org/10.3390/diagnostics13040789 https://www.mdpi.com/journal/diagnostics