Ole Lajord Munk, March 2016

The Mediso nanoScan PET/MRI scanner was delivered from Mediso Medical Imaging Systems in 2013.
The MRI part of the system is a self-shielded 1T permanent MRI magnet, which does not require cooling. We have two radiofrequency coils, a 35-mm and a 60-mm diameter coil, used for imaging of mice and rats, respectively. MR imaging can be performed using 2D and 3D sequences such as spin echo and gradient echo. The MRI provides good soft tissue contrast required for anatomical/morphological imaging with a spatial resolution down to 0.1 mm.
The PET part consist 12 detector modules, with a total of 38,000 lutetium yttrium oxyorthosilicate (LYSO) crystals of 1.1 x 1.1 x 13 mm3, and magnetically shielded position-sensitive photomultiplier tubes. The PET system has a 9.4 mm (axial) and 12.0 mm (transaxial) coverage. PET data are acquired in list-mode, and several reconstruction methods are available including 3D iterative reconstruction with all corrections including attenuation and scatter in the animal, detector geometry (PSF), depth-of-interaction (DOI), and positron range. The resulting PET images have a high and relatively uniform spatial resolution around 0.7 mm. We currently use the PET/MRI-system for small-animal research in brain, kidney and tumour physiology using a variety of PET tracers.