Development and Evaluation of mini-EXPLORER: A Long Axial Field-of-View PET Scanner for Nonhuman Primate Imaging

Area of Science:

• Nuclear Medicine
• Medical Imaging
• Preclinical Research

Background:

• Positron Emission Tomography (PET) scanners with long axial fields-of-view (FOV) are crucial for high-sensitivity imaging.
• Existing scanners often have limitations in sensitivity and total-body coverage for nonhuman primate studies.
• Optimizing scanner geometry and acceptance angle is key to maximizing performance.

Purpose of the Study:

• To describe the design and physical performance of a novel long axial FOV PET scanner, the mini-EXPLORER.
• To evaluate the scanner's capabilities for high-sensitivity and total-body imaging of nonhuman primates.
• To assess the impact of a wide acceptance angle on scanner performance.

Main Methods:

• The mini-EXPLORER PET scanner was constructed using clinical components, featuring a 43.5 cm diameter and 45.7 cm axial length.
• National Electrical Manufacturers Association (NEMA) NU-2 and NU-4 phantoms were used to measure sensitivity, count rates, and spatial resolution.
• Performance was evaluated across different acceptance angles (14°-46°), and in vivo imaging was conducted using 18F-FDG in a rhesus monkey.

Main Results:

• The mini-EXPLORER achieved a total sensitivity of 5.0% and a peak noise-equivalent count rate of 1,741 kcps at a 46° acceptance angle.
• Spatial resolution was approximately 3.0 mm at the center of the FOV, with a minor axial resolution degradation at wider angles.
• In vivo studies demonstrated high sensitivity, enabling fast (1-s frames) and high-quality imaging (30-s to 5-min frames) at a single bed position.

Conclusions:

• The mini-EXPLORER PET scanner demonstrates excellent physical performance and imaging capabilities for nonhuman primates.
• A wide acceptance angle effectively maximizes sensitivity with only minor trade-offs in scatter fraction and axial resolution.
• This long axial FOV PET scanner is well-suited for advanced preclinical research requiring high sensitivity and total-body coverage.