Contents lists available at ScienceDirect Radiation Physics and Chemistry journal homepage: www.elsevier.com/locate/radphyschem Impact of muscular uptake and statistical noise on tumor quantification based on simulated FDG-PET studies Jesús Silva-Rodríguez a , Inés Domínguez-Prado b , Juan Pardo-Montero a,c, ⁎ , A. Álvaro Ruibal a,b,d,e , Pablo Aguiar a,d, ⁎ a Grupo de Investigación en Imaxe Molecular, Instituto de Investigación Sanitarias (IDIS), Santiago de Compostela, Galicia, Spain b Servizo de Medicina Nuclear, Complexo Hospitalario Universitario de Santiago de Compostela, Galicia, Spain c Servizo de Radiofísica e Protección Radiolóxica, Complexo Hospitalario Universitario de Santiago de Compostela, Galicia, Spain d Departamento de Psiquiatría, Radioloxía e Saúde Pública, Facultade de Medicina, Universidade Santiago Compostela, Spain e Fundación Tejerina, Madrid, Spain ARTICLE INFO Keywords: PET SUV Quantification ABSTRACT Purpose: The aim of this work is to study the effect of physiological muscular uptake variations and statistical noise on tumor quantification in FDG-PET studies. Methods: We designed a realistic framework based on simulated FDG-PET acquisitions from an anthro- pomorphic phantom that included different muscular uptake levels and three spherical lung lesions with diameters of 31, 21 and 9 mm. A distribution of muscular uptake levels was obtained from 136 patients remitted to our center for whole-body FDG-PET. Simulated FDG-PET acquisitions were obtained by using the Simulation System for Emission Tomography package (SimSET) Monte Carlo package. Simulated data was reconstructed by using an iterative Ordered Subset Expectation Maximization (OSEM) algorithm implemented in the Software for Tomographic Image Reconstruction (STIR) library. Tumor quantification was carried out by using estimations of SUV max , SUV 50 and SUV mean from different noise realizations, lung lesions and multiple muscular uptakes. Results: Our analysis provided quantification variability values of 17–22% (SUV max ), 11–19% (SUV 50 ) and 8– 10% (SUV mean ) when muscular uptake variations and statistical noise were included. Meanwhile, quantification variability due only to statistical noise was 7–8% (SUV max ), 3–7% (SUV 50 ) and 1–2% (SUV mean ) for large tumors ( > 20 mm) and 13% (SUV max ), 16% (SUV 50 ) and 8% (SUV mean ) for small tumors ( < 10 mm), thus showing that the variability in tumor quantification is mainly affected by muscular uptake variations when large enough tumors are considered. In addition, our results showed that quantification variability is strongly dominated by statistical noise when the injected dose decreases below 222 MBq. Conclusions: Our study revealed that muscular uptake variations between patients who are totally relaxed should be considered as an uncertainty source of tumor quantification values. 1. Introduction Current potential of FDG-PET relies on its capability to provide quantitative information about glucose metabolism, enabling an objec- tive tumor characterization and therefore a reliable differential diag- nosis or earlier evaluation of treatment response (Bourland, 2006; Jeraj and Machtay, 2008; Fletcher et al., 2008; Freudenberg et al., 2008; Ben-Haim et al., 2009). The quantitative analysis is usually performed by using a semi-quantitative parameter known as Standard Uptake Value (SUV) that is routinely measured in most centers (90%) (Beyer et al., 2011). Nevertheless, this quantitative parameter must be used carefully since it can be affected by many different error sources, such as physiological changes between different studies from the same patient (Boellaard, 2009), patient management issues (Silva-Rodríguez et al., 2014) or technical issues related to acquisition (Wijesooriya et al., 2013; Musarudin et al., 2015), reconstruction (Boellaard et al., 2004) and quantification protocols (Boellaard et al., 2008, 2010). Additional errors due to different procedures and methodologies across institutions can affect multicenter studies (Adams et al., 2010; Graham et al., 2011). Many authors have pointed to the need for further methodology standardization in order to minimize the impact of these effects and thus increase the reliability of SUV measurements http://dx.doi.org/10.1016/j.radphyschem.2016.10.015 Received 11 September 2015; Received in revised form 20 September 2016; Accepted 23 October 2016 ⁎ Corresponding authors at: Servizo de Medicina Nuclear, Complexo Hospitalario Universitario de Santiago de Compostela, Galicia, Spain. E-mail addresses: juan.pardo.montero@sergas.es (J. Pardo-Montero), pablo.aguiar.fernandez@sergas.es (P. Aguiar). Radiation Physics and Chemistry 131 (2017) 28–34 0969-806X/ © 2016 Elsevier Ltd. All rights reserved. Available online 26 October 2016 crossmark