Introduction: Combined functional imaging, using information gathered by multiple modalities such as Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) opens new horizons in medical research. In this study we present two novelties, so far not shown in small animal imaging. By sequential PET and MR imaging we were able to study and compare brain activation in animals using [O]H2O PET and BOLD fMRI. In addition we were able to obtain in vivo BOLD data inside a MR compatible small animal PET-Insert [1], allowing future simultaneous PET/MR studies.

The combination of Positron Emission Tomography (PET) and Magnetic Resonance (MR) is a promising tool in biomedical research and clinical diagnostic imaging. In this study we performed to our knowledge the first simultaneous PET and MR perfusion measurements using [O]water, as a PET perfusion marker, and arterial spin labeling (ASL), for MR perfusion measurements, in small animals. Due to the isochronous collection of data we were able to minimize confounding parameters such as variations in the physiology and compare quantitatively these two perfusion measurement approaches.

H. F. Wehrl, M. S. Judenhofer, P. Martirosian, F. Maier, G. Reischl, F. Schick, and B. J. Pichler Laboratory for Preclinical Imaging of the Werner Siemens-Foundation, Department of Radiology, University of Tuebingen, Tuebingen, BW, Germany, Section on Experimental Radiology, Department of Radiology, University of Tuebingen, Tuebingen, BW, Germany, Radiopharmacy and PET-Center, Department of Radiology, University of Tuebingen, Tuebingen, BW, Germany