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Abstract:
The combination of positron emission tomography (PET) and magnetic resonance imaging (MRI), enabling truly simultaneous acquisition, will bridge the gap between molecular and systems functional imaging and diagnosis. MRI and PET offer richly complementary functionality and sensitivity; fusion into a combined system enabling to image neuroscientific molecular processes (e.g. neuromodulators such as dopamine and serotonine) and cerebral blood flow and blood oxygenation simultaneously. Furthermore, information obtained by MRI can be used to improve analysis and reconstruction of PET images (e.g. motion information or structural information for attenuation correction). Using a developed animal PET/MRI system in Tübingen, we have shown excellent performance in both phantom and in vivo examinations (Nature Medicine Apr;14(4):459-65). The new human BrainPET consists of a PET detector that can be inserted into a 3 Tesla TIM Trio (Siemens Medical Solutions) human MRI system. The BrainPET was designed to operate silently in the frequency range used for MR imaging at 3T, making it compatible with the advanced MR brain imaging protocols that can be performed at this field strength. The BrainPET is the first human PET system which is to be designed to be insensitive to magnetic fields by using Avalanche Photodiodes instead of PMTs as light detectors, and non-magnetic detector and front-end electronic materials. A first prototype BrainPET has been built by Siemens in close collaboration with the University of Tübingen. It seems to be obvious that the combination of PET and MRI would be advantageous over PET/CT. Especially the combination of morphology with multi-functional information, from PET, MRS, MRI and fMRI in one examination paves the way for a new perspective in molecular imaging. Furthermore, in sharp contrast to PET/CT, PET/MRI data could be acquired simultaneously rather than sequentially, allowing a more accurate correlation of the different data sets.
