ORIGINAL PAPER FDG–PET can distinguish inflamed from non-inflamed plaque in an animal model of atherosclerosis John R. Davies Æ David Izquierdo-Garcia Æ James H. F. Rudd Æ Nichola Figg Æ Hugh K. Richards Æ Joseph L. E. Bird Æ Franklin I. Aigbirhio Æ Anthony P. Davenport Æ Peter L. Weissberg Æ Tim D. Fryer Æ Elizabeth A. Warburton Received: 18 January 2009 / Accepted: 29 August 2009 / Published online: 22 September 2009 Ó Springer Science+Business Media, B.V. 2009 Abstract The presence of activated macrophages is an important predictor of atherosclerotic plaque rup- ture. In this study, our aim was to determine the accuracy of 18 F- fluorodeoxyglucose (FDG) microPET imaging for quantifying aortic wall macrophage con- tent in a rabbit model of atherosclerosis. Rabbits were divided into a control group and two groups post aortic balloon injury: 6 months high-cholesterol diet (HC); and 3 months HC followed by 3 months low- cholesterol diet plus statin (LCS). In vivo and ex vivo microPET, ex vivo well counting and histological quantification of the atherosclerotic aortas were per- formed for all groups. Macrophage density was greater in the HC group than the LCS group (5.1 ± 1.4% vs. 0.6 ± 0.7%, P \ 0.001) with a trend towards greater macrophage density in LCS compared to controls (P = 0.08). There was a strong correlation across all groups between macrophage density and standardized uptake value (SUV) derived from ex vivo microPET (r = 0.95, P \ 0.001) and well counting (r = 0.96, P \ 0.001). Ex vivo FDG SUV was significantly different between the three groups (P \ 0.001). How- ever, the correlation between in vivo microPET FDG SUV and macrophage density was insignificant (r = 0.16, P = 0.57) with no statistical differences in FDG SUV seen between the three groups. This study confirms that in an animal model of inflamed and non- inflamed atherosclerosis, significant differences in FDG SUV allow differentiation of highly inflamed atherosclerotic aortas from those stabilized by statin therapy and low cholesterol diet and controls. Keywords PET Á FDG Á Inflammation Á Atherosclerosis Á Animal model Introduction The presence of inflammatory cells, particularly macrophages, in the intimal layer of the arterial wall The authors John R. Davies and David Izquierdo-Garcia have contributed equally to the study. J. R. Davies Á J. H. F. Rudd Á N. Figg Á P. L. Weissberg Division of Cardiovascular Medicine, University of Cambridge, Addenbrooke’s Hospital, Cambridge, UK D. Izquierdo-Garcia (&) Á J. L. E. Bird Á F. I. Aigbirhio Á T. D. Fryer Wolfson Brain Imaging Centre, University of Cambridge, Addenbrooke’s Hospital, Box 65, Cambridge CB2 0QQ, UK e-mail: di219@wbic.cam.ac.uk H. K. Richards Department of Neurosurgery, University of Cambridge, Addenbrooke’s Hospital, Cambridge, UK J. L. E. Bird Á A. P. Davenport Clinical Pharmacology Unit, University of Cambridge, Addenbrooke’s Hospital, Cambridge, UK E. A. Warburton Clinical Neurosciences, University of Cambridge, Addenbrooke’s Hospital, Cambridge, UK 123 Int J Cardiovasc Imaging (2010) 26:41–48 DOI 10.1007/s10554-009-9506-6