Performance measurement of a PET insert using strip-line readout and waveform sampling data acquisition for simultaneous PET/MRI

Previously we reported the development of a PET insert for PET/MRI using strip-line signal readout and waveform sampling data acquisition for small animal imaging. Based on encouraging results obtained from the previous prototype, we have made several major upgrades for improvement. Firstly, the number of detector modules were increased from 8 to 14 to increase sensitivity and eliminate image artifacts. Each detector module consists of 8x4 LYSO arrays (3x3x10 mm
³
each) and two Hamamatsu S13361-3050NE-04 MPPC arrays (4x4, 3.2 mm pitch). The detector modules are installed within a 3d-printed plastic supporting structure with 60 mm inner diameter and 115 mm outer diameter to fit inside 9.4 Tesla Bruker BioSpec 94/30 USR MR scanner. The axial field of view of the PET insert is 25.6 mm. Secondly, the SiPM signal readout multiplexing ratio is increased double in the detector module by redesigning the strip-line board;32 SiPM signals from MPPC arrays are routed to 2 strip-lines so that 16 LYSO/SiPMs send outputs to a common strip-line for readout. Experiments using the PET insert have been conducted inside and outside an MR scanner for performance evaluation. The mutual interferences of the integrated system are assessed by comparing PET and MR images of a custom-made resolution phantom. Preliminary test results are very promising and demonstrate that detector design based on strip-line signal readout is suitable for PET/MR system. We present the development of the PET insert and the preliminary experimental results.