MRI-compatibility study of a PET-insert based on a low-profile detection front-end with submillimeter spatial...

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Biomedical Engineering

Background:

• The LabPET II detection module shows promise for creating MRI-compatible PET inserts with submillimeter resolution for small animal studies.
• Challenges include the module's radial size and the presence of ferromagnetic components, hindering its integration into MRI systems.
• A novel low-profile detection module, based on the LabPET II architecture, is investigated to overcome these limitations.

Purpose of the Study:

• To evaluate the performance of a new low-profile detection module designed for MRI compatibility.
• To assess the impact of MRI-like radiofrequency (RF) signals and gradient coil pulses on the module's performance.
• To investigate the effectiveness of shielding in mitigating electromagnetic interference (EMI) for simultaneous PET/MRI applications.

Main Methods:

• The low-profile detection module's analog signal baseline, RMS noise, and energy resolution (using dual time-over-threshold) were measured under various MRI-like RF and gradient pulse conditions.
• Performance was evaluated inside a 7T MRI scanner using gradient echo sequences, assessing effects on MR images.
• Measurements were repeated for a shielded version of the module, both inside and outside the MRI environment.

Main Results:

• Unshielded module experienced up to 50% increase in noise and 17% degradation in energy resolution due to RF and gradient pulses.
• Shielding the module with a conducting composite layer effectively eliminated these degrading effects.
• The shielded module performed consistently inside and outside the 7T MRI, and acquired MR images showed no artifacts, confirming EMI immunity.

Conclusions:

• The low-profile detection module is a viable PET-insert candidate for simultaneous PET/MRI due to its thin profile and improved EMI performance.
• Shielding is crucial for mitigating electromagnetic interference, ensuring comparable performance inside and outside the MRI.
• The shielded module enables simultaneous PET/MRI operation without compromising PET data or MR image quality.