Simultaneous PET and MR Imaging with a Newly Developed 3TMR-BrainPET Scanner

A prototype of a new bimodal scanner was installed in our laboratory. This scanner combines magnetic resonance imaging (MRI) and positron emission tomography (PET) for brain studies. As the PET detector is located within the bore of the MRI scanner, simultaneous measurements become possible. The MR-component consists of a commercial 3T MRI scanner MAGNETOM Tim-Trio, whereas the PET detector BrainPET has been newly developed. The readout electronics of the PET are based on avalanche photodiodes (APDs) which can be applied in the magnetic field. The inner diameter of the PET ring, which consists of 32 cassettes, is 36 cm so that an MRI head coil can be inserted into this ring. First tests were carried out to analyse the countrate behaviour and the image resolution. To assess the image quality of simultaneous MR-PET, phantom studies were performed. The image resolution in the centre was between 2.1 and 2.5mm in x,y and z directions. First MR-PET studies showed no visible artefacts of the MR image and FDG-PET images provided high-resolution delineation of the cortex.