Experimental Validation of a Preclinical SPECT/MR Insert

The experimental characterization of a SiPM-based 10-module SPECT gamma imager suitable for insertion and operation inside unmodified MR scanners for simultaneous (and potentially multi-tracer) preclinical imaging is presented. The design challenges, here fulfilled, such as compactness while granting proper cooling, mutual compatibility and resilience to high (3-7 T) magnetic fields inside the bore, suitable energetic (better than 14% at 140 keV) and spatial resolution (better than 1 mm) are discussed. The carefully optimized detection module, featuring a 5 × 5 cm
²
CsI(Tl) scintillator coupled to arrays of SiPM conditioned by a 36-channel ASIC, and the digital daisy chain infrastructure are the basis for the realization of a larger (20-module ring) clinical insert. Moreover, planar image reconstruction based on advanced statistical approaches such as maximum likelihood and iteratively estimated light response function is reported.