PETcoil: first results from a second-generation RF-penetrable TOF-PET brain insert for simultaneous PET/MRI

Area of Science:

• Medical Imaging
• Physics
• Engineering

Background:

• Simultaneous Positron Emission Tomography (PET)/Magnetic Resonance Imaging (MRI) offers integrated anatomical, functional, and molecular insights for disease diagnosis.
• Advancements in PET/MRI technology are crucial for improving diagnostic capabilities.

Purpose of the Study:

• To report the initial system performance of a novel, second-generation, MR-compatible, radiofrequency-penetrable Time-of-Flight PET insert.
• To evaluate the spatial resolution, sensitivity, and stability of the full-ring PET insert.

Main Methods:

• Developed a full-ring PET insert with smaller scintillation crystals and ring diameter for enhanced resolution and sensitivity.
• Utilized 12,288 LYSO-SiPM channels with a crystal size of 3.2 × 3.2 × 20 mm³.
• Conducted stability tests over ten hours and resolution phantom studies (2.8 mm rods).
• Performed initial MR compatibility studies with the unpowered PET ring.

Main Results:

• Preserved global photopeak energy resolution (11.74 ± 0.03 % FWHM) and coincidence time resolution (238.1 ± 0.5 ps FWHM).
• Achieved successful resolution of 2.8 mm rods in phantom studies, with VPR of 0.28 ± 0.08 (no TOF) and 0.24 ± 0.07 (TOF).
• Demonstrated stable system performance (<1% change over 10 hours) and enhanced image quality with TOF.
• No observable MR artifacts detected during initial unpowered MR compatibility tests, though SNR degradation (~30%) occurred with the body coil.

Conclusions:

• The developed MR-compatible TOF-PET insert demonstrates promising performance with high spatial resolution and sensitivity.
• The system exhibits stable operation and potential for improved image quality through TOF reconstruction.
• Further development is needed for a dedicated receive-only MR coil to mitigate SNR degradation.