Spatial resolution of the Inveon small-animal PET scanner for the entire field of view

In high throughput small-animal positron emission tomography (PET) studies, it can be advantageous to scan more than one animal at the same time. To optimally position these animals in the scanner, both sensitivity and spatial resolution have to be known across the entire field of view (FOV). The Siemens Inveon small-animal PET scanner has been characterized according to NEMA NU 4-2008 standards, but the spatial resolution has only been determined in a small portion of the FOV and only for filtered backprojection (FBP). In this study, the spatial resolution in the entire FOV was determined for the Inveon using FBP, ordered subset expectation maximization in 2 dimensions (OSEM2D) and maximum a posteriori (MAP) reconstructions. OSEM2D produced the best spatial resolution in the axial center of the FOV, but MAP outperformed the two other reconstruction algorithms in terms of uniformity of the resolution.