Eur Radiol (2010) 20: 1180–1187 DOI 10.1007/s00330-009-1634-9 C H E S T Ying Wang Geertruida H. de Bock Rob J. van Klaveren Peter van Ooyen Wim Tukker Yingru Zhao Monique D. Dorrius Rozemarijn Vliegenthart Proença Wendy J. Post Matthijs Oudkerk Received: 11 May 2009 Revised: 29 September 2009 Accepted: 1 October 2009 Published online: 18 November 2009 # The Author(s) 2009. This article is published with open access at Springerlink.com Y. Wang . P. van Ooyen . W. Tukker . Y. Zhao . M. D. Dorrius . R. V. Proença . M. Oudkerk (*) Department of Radiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9700 RB Groningen, The Netherlands e-mail: m.oudkerk@rad.umcg.nl Tel.: +31-503-614260 Fax: +31-503-611798 G. H. de Bock . W. J. Post Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands R. J. van Klaveren Department of Pulmonology, Erasmus Medical Center, Rotterdam, The Netherlands Introduction Volumetric measurement of pulmonary nodules at low-dose chest CT: effect of reconstruction setting on measurement variability Abstract Objective: To assess volumetric measurement variability in pulmonary nodules detected at low-dose chest CT with three reconstruction settings. Methods: The volume of 200 solid pulmonary nodules was measured three times using commercially available semi-automated software of low-dose chest CT data-sets reconstructed with 1 mm section thickness and a soft kernel (A), 2 mm and a soft kernel (B), and 2 mm and a sharp kernel (C), respectively. Repeatability coefficients of the three measurements within each setting were calculated by the Bland and Altman method. A three-level model was applied to test the impact of reconstruction setting on the measured volume. Results: The repeatability coefficients were 8.9, 22.5 and 37.5% for settings A, B and C. Three-level analysis showed that settings A and C yielded a 1.29 times higher estimate of nodule volume compared with setting B (P= 0.03). The significant interaction among setting, nodule location and morphology demonstrated that the effect of the reconstruction setting was different for different types of nodules. Low-dose CT reconstructed with 1 mm section thickness and a soft kernel provided the most repeatable volume measurement. Conclusion: A wide, nodule-type-dependent range of agreement between volume measurements with different reconstruction settings suggests strict consistency is required for serial CT studies. Keywords Multi-detector computed tomography . Pulmonary nodules . Volume measurement . Section thickness . Reconstruction kernel Currently, an increasing number of pulmonary nodules are being detected incidentally with the evolution of multi- detector computed tomography (CT) technology and the use of high resolution images [1]. Assessment of changes in nodule volume to determine the volume doubling time based on serial CT examinations has proven to be a valuable tool in the differentiation between benign and malignant pulmonary nodules as malignant nodules typically present with a volume doubling time between 30 and 400 days [2–7]. Three-dimensional (3-D) volumetric measurements are more accurate and reproducible than two-dimensional measure- ments and are increasingly used in lung cancer screening programs and tumour response evaluation after chemother- apy [8–13]. However, none of the available 3-D software tools appears to be completely reproducible and a certain degree of variability exists [14–18]. Potential sources of volumetric measurement error are, in addition to the type of software used, also dependent on the reader, nodule characteristics, imaging and reconstruction settings [15–17]. Several studies [19–22] explored the effect of reconstruction settings on volume measurement variability, but they are derived from