In this report, PEM scanner using a Pr:LuAG scintillator crystal will be discussed. We have developed the PEM scanner with planer detectors which can change the angle and the distance depending on the condition of diagnosis. The planer detectors were composed of four units respectively and one unit consisted of a 20 × 64 pixels scintillator array optically coupled with three H8500 multi anode photomultipliers. As a scintillator Pr:LuAG was installed which possesses interesting properties such as a very fast decay time of 20 ns and a good energy resolution of 4.2 %. The Pr:LuAG pixel size was 2.1 mm × 2.1 mm × 15 mm and the BaSO4-type reflector was used for the array assembly. Based on this PEM system we have performed the clinical studies and compared with the images detected by the PET scanner. Because the spatial resolution of PEM is better than PET, advantages of PEM scanner were clearly shown.