Development of a combined microPET-MR system

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Nuclear Medicine

Background:

• Combining PET and MR imaging (PET-MR) offers superior soft tissue contrast and reduced radiation dose compared to PET-CT.
• Conventional PET detectors using photomultiplier tubes (PMTs) are sensitive to magnetic fields, posing a challenge for PET-MR integration.
• Alternative approaches include using magnetic field-insensitive detectors (APDs, SiPMs) or modifying existing systems.

Purpose of the Study:

• To develop and test a modified PET system compatible with a 1T MR scanner for small animal imaging.
• To evaluate methods for mitigating magnetic field effects on PMT-based PET detectors within an MR environment.

Main Methods:

• A microPET Focus 120 scanner was modified and integrated into a novel 1T superconducting magnet.
• Fiber optic bundles were used to shield PMTs from the main magnetic field, placing them in a ~30mT region.
• Key system features, including the use of long fiber optic bundles and the magnetic field's impact on PMTs, were tested.

Main Results:

• The design for a modified microPET-MR system for small animal imaging has been completed.
• Assembly and initial testing of the modified system are currently in progress.
• The study is evaluating the performance of PMTs shielded by fiber optics within the MR's magnetic field.

Conclusions:

• The integration of PET and MR imaging is feasible with system modifications to address magnetic field interference.
• This approach enables simultaneous PET-MR imaging, potentially improving diagnostic accuracy and reducing radiation exposure.
• The modified system is expected to advance small animal research and preclinical imaging applications.