ORIGINAL PAPER Influence of iterative image reconstruction on CT-based calcium score measurements Jochen A. C. van Osch • Mohamed Mouden • Jorn A. van Dalen • Jorik R. Timmer • Stoffer Reiffers • Siert Knollema • Marcel J. W. Greuter • Jan Paul Ottervanger • Piet L. Jager Received: 10 December 2013 / Accepted: 21 March 2014 / Published online: 28 March 2014 Ó Springer Science+Business Media Dordrecht 2014 Abstract Iterative reconstruction techniques for coronary CT angiography have been introduced as an alternative for traditional filter back projection (FBP) to reduce image noise, allowing improved image quality and a potential for dose reduction. However, the impact of iterative recon- struction on the coronary artery calcium score is not fully known. In 112 consecutive stable patients with suspected coronary artery disease, the coronary calcium scores were assessed. Comparisons were made between the Agatston, volume and mass scores obtained with traditional FBP, and by using adaptive statistical iterative reconstruction (ASIR). A significant reduction of the Agatston score, volume score and mass score was observed for ASIR when compared to FBP, with median differences of resp. 26, 5 mm 3 and 1 mg. Using the ASIR reconstruction, the number of patients with a calcium score of zero increased by 13 %. Iterative CT reconstruction significantly reduces the Agatston, volume and mass scores. Since the calcium score is used as a prognostic tool for coronary artery disease, caution must be taken when using iterative reconstruction. Keywords Iterative image reconstruction Á Computed tomography Á Cardiac imaging techniques Á Coronary stenosis Á Coronary disease Á Calcium scoring Abbreviations FBP Filtered back projection IR Iterative reconstruction ASIR Adaptive statistical iterative reconstruction CAC Coronary artery calcium CAD Coronary artery disease CCTA Coronary CT angiography Introduction Coronary artery calcium (CAC) scoring is a well-validated clinical tool for the early detection of coronary artery atherosclerosis and provides valuable prognostic informa- tion [1–3]. In symptomatic patients, CAC scoring may be applied for the exclusion of obstructive coronary artery disease (CAD) in selected populations [4–9]; while in most centers CAC scoring is routinely assessed prior to coronary CT angiography (CCTA). Furthermore, simultaneous CAC scoring is increasingly used in patients referred for myo- cardial perfusion imaging (MPI) [10], as such enhancing the diagnostic process and potentially influencing post- imaging clinical management [11, 12]. However, increasingly concerns have been raised with regard to the radiation exposure associated with medical imaging procedures, including non-invasive cardiac CT J. A. C. van Osch Á J. A. van Dalen Department of Medical Physics, Isala Hospital, Zwolle, The Netherlands J. A. C. van Osch (&) Á S. Reiffers Á S. Knollema Á P. L. Jager Department of Nuclear Medicine, Isala Hospital, Dr. van Heesweg 2, 8025 AB Zwolle, The Netherlands e-mail: j.a.c.van.osch@isala.nl M. Mouden Á J. R. Timmer Á J. P. Ottervanger Department of Cardiology, Isala Hospital, Zwolle, The Netherlands M. J. W. Greuter Department of Radiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands 123 Int J Cardiovasc Imaging (2014) 30:961–967 DOI 10.1007/s10554-014-0409-9