Evaluation of the co-registration capabilities of a MRI/PET compatible bed in an Experimental autoimmune encephalomyelitis (EAE) model Giovanna Esposito a,n , Luca D’angeli a , Antonietta Bartoli a,1 , Linda Chaabane b , Enzo Terreno a a Molecular and Preclinical Imaging Center, University of Torino, Italy b INSPE-Division of Neuroscience, San Raffaele Scientific Institute, 20132 Milano, Italy article info Available online 7 September 2012 Keywords: PET MRI EAE 18 F-FDG abstract Positron Emission Tomography (PET) with 18 F-FDG is a promising tool for the detection and evaluation of active inflammation in animal models of neuroinflammation. MRI is a complementary imaging technique with high resolution and contrast suitable to obtain the anatomical data required to analyze PET data. To combine PET and MRI modalities, we developed a support bed system compatible for both scanners that allowed to perform imaging exams without animal repositioning. With this approach, MRI and PET data were acquired in mice with Experimental autoimmune encephalomyelitis (EAE). In this model, it was possible to measure a variation of 18 F-FDG uptake proportional to the degree of disease severity which is mainly related to Central Nervous System (CNS) inflammation. Against the low resolved PET images, the co-registered MRI/PET images allowed to distinguish the different brain structures and to obtain a more accurate tracer evaluation. This is essential in particular for brain regions whose size is of the order of the spatial resolution of PET. & 2012 Elsevier B.V. All rights reserved. 1. Introduction In vivo neuroimaging in small animal models can provide important insights into the understanding of a given neuropathology, thereby playing a fundamental role not only for diagnostic purposes, but also for the selection of the most appropriate therapeutic [1,2]. Despite the high sensitivity and specificity, Positron Emission Tomo- graphy (PET) is limited in small animal models due to the poor spatial resolution that leads to a reduced ability to quantify tracer uptake in specific regions of interest (ROIs). To overcome this limit, morphological imaging techniques such as Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) are used. MRI is a relevant imaging tool extensively used to detect brain damages in different pathologies. However, the limited sensitivity of the tech- nique does not allow the assessment of brain functions. In the present work, we evaluated the MRI–PET co-registration capabilities of an home-built support specifically developed to adapt a MRI bed to PET imaging. With this system, both MRI and PET were acquired in sequential mode without animal reposition- ing, thus avoiding motions and enabling a direct co-registration of functional and morphological data. To evaluate the relevance of this support, experiments were performed in a model of Multiple Sclerosis, the Experimental autoimmune encephalomyelitis (EAE) induced in mice. EAE is the most commonly used model for human inflammatory and demyelination disease of the CNS such as multiple sclerosis [3] and it is particularly suitable to explore the complex mechanism of the immune and neural systems to investigate new therapies. In a previous work [4], the uptake of 2-[ 18 F]fluoro-2-deoxy-D-glucose ( 18 F-FDG) has been suggested as a reliable marker of inflammation in an EAE mouse model, thus this tracer was used in our animal model to evaluate the co-registration capabilities of the bed system and to monitor the disease progres- sion. To this end, both 18 F-FDG–PET imaging and MRI were performed at different phases of disease development in EAE model. 2. Materials and methods 2.1. MRI/PET compatible bed MRI acquisitions were performed with a preclinical 7 T scan- ner (Pharmascan, Bruker), while PET scans were performed with the YAP(S)PET (ISE S.r.l.) [6]. The YAP(S)PET scanner is equipped with a carbon fiber bed which is incompatible with MRI. There- fore, a steel support for the YAP-(S)PET, specifically designed to embed the MRI plexiglas bed, was manufactured (Fig. 1A). With this support, it was possible to perform both MRI and PET in sequential mode (Fig. 1B and C) by keeping the animal under anesthesia and without moving the animal from its original position. Once MRI scans were performed, the bed was removed, transported to the PET scan and mounted on the steel support. Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/nima Nuclear Instruments and Methods in Physics Research A 0168-9002/$ - see front matter & 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.nima.2012.08.102 n Corresponding author. Tel.: þ39 012 5538942x515. E-mail address: giovanna.esposito@unito.it (G. Esposito). 1 Present address: CNR, Institute of Clinical Physiology, Pisa, Italy. Nuclear Instruments and Methods in Physics Research A 702 (2013) 108–110