# Design and Performance Assessment of a High-Resolution Small-Animal PET System

## TL;DR

A new high-resolution PET system for small animals was developed and tested, showing strong performance in imaging mice and rats for preclinical research.

## Contribution

A novel small-animal PET system using LYSO crystals and MPPC is evaluated for high-resolution and high-sensitivity imaging.

## Key findings

- The system achieved a tangential spatial resolution of 0.9 mm using 3D OSEM reconstruction.
- Peak sensitivity of 8.74% and average energy resolution of 12.5% were recorded.
- NECR reached 878.7 kcps for mouse phantom and 421.4 kcps for rat phantom at specific activity levels.

## Abstract

This work reports the performance evaluation of a newly developed small-animal positron emission tomography (PET) system based on lutetium-yttrium oxyorthosilicate (LYSO) crystals and multi-pixel photon counter (MPPC). Performance was evaluated, including spatial resolution, system sensitivity, energy resolution, scatter fraction (SF), noise–equivalent count rate (NECR), micro-Derenzo phantom imaging, and in vivo imaging of mice and rats. The system achieved a tangential spatial resolution of 0.9 mm in the axial direction at a quarter axial offset using the three-dimensional ordered-subsets expectation maximization (3D OSEM) reconstruction algorithm. The peak sensitivity was 8.74% within a 200–750 keV energy window, with an average energy resolution of 12.5%. Scatter fractions were 12.9% and 30.0% for mouse- and rat-like phantoms, respectively. The NECR reached 878.7 kcps at 57.6 MBq for the mouse phantom and 421.4 kcps at 63.2 MBq for the rat phantom. High-resolution phantom and in vivo images confirmed the system’s capability for quantitative, high-sensitivity small-animal imaging, demonstrating its potential for preclinical molecular imaging studies.