PET/MR Imaging in Vascular Disease Atherosclerosis and Inflammation Rasmus Sejersten Ripa, MD, DMSc, Sune Folke Pedersen, PhD, Andreas Kjær, MD, PhD, DMSc* INTRODUCTION Within imaging of atherosclerotic disease, in everyday clinical practice the approach of lume- nography using computed tomography (CT), ultra- sonography, or invasive angiography is still the backbone of evaluation. Although this approach has merit as preoperative evaluation, that is, whether invasive procedures, such as endarterec- tomy, percutaneous coronary intervention, and coronary artery bypass grafting, to remove steno- sis are likely to be successful, these methods are less effective to predict the likelihood of future thromboembolic events caused by vulnerability of plaques. As an example of the shortcoming of using the degree of stenosis for risk stratification is the selection of patients that shall undergo carotid endarterectomy. Here the numbers needed to treat are as high as 6 to 1. 1 Accordingly, it is increasingly acknowledged that molecular and functional imaging approaches are needed. Both PET and MR imaging have been used separately for plaque characterization, whereas this is not to the same extent the case for CT, apart from eval- uation of calcification; therefore, the use of hybrid imaging with PET/MR imaging may seem particu- larly relevant for the evaluation of atherosclerosis and plaques. Indeed, at the fourth International Workshop on PET/MR Imaging held in Tu ¨ bingen in 2015 there was in particular optimism for the use of PET/MR imaging in cardiovascular disease where it was even suggested that it could become a primary clinical application of hybrid PET/MR im- aging. 2 Here, the authors shall not judge whether The authors have nothing to disclose. The authors have received generous support from the John & Birthe Meyer Foundation, the National Advanced Technology Foundation, The Innovation Fund Denmark, Danish Medical Research Council, Rigshospitalet Research Foundation, Svend Andersen Foundation, AP Møller Foun- dation, Novo Nordisk Foundation, and Lundbeck Foundation to perform studies reported here. Department of Clinical Physiology, Nuclear Medicine & PET and Cluster for Molecular Imaging, Rigshospitalet and University of Copenhagen, KF-4012, Rigshosptialet, Blegdamsvej 9, Copenhagen 2100, Denmark * Corresponding author. E-mail address: akjaer@sund.ku.dk KEYWORDS  PET/MR  PET/CT  Molecular imaging  Atherosclerosis  Vulnerable plaque  Cardiovascular disease  Inflammation  Macrophages KEY POINTS  For evaluation of risk of thromboembolic events, such as stroke and acute myocardial infarction, molecular imaging of plaque vulnerability is more relevant than the degree of stenosis.  PET/MR imaging is a favorable combination for plaque imaging, as PET can visualize plaque activity and MR imaging can visualize plaque composition.  Vascular imaging of atherosclerosis and atherosclerotic plaques may become a major application of hybrid PET/MR imaging.  So far, surprisingly few studies using PET/MR imaging for imaging of atherosclerosis have been published. PET Clin 11 (2016) 479–488 http://dx.doi.org/10.1016/j.cpet.2016.05.009 1556-8598/16/$ – see front matter Ó 2016 Elsevier Inc. All rights reserved. pet.theclinics.com Downloaded from ClinicalKey.com at BS - University of Copenhagen October 19, 2016. For personal use only. No other uses without permission. Copyright ©2016. Elsevier Inc. All rights reserved.