MRI compatibility study of an integrated PET/RF-coil prototype system at 3T

Area of Science:

• Medical Imaging
• Biophysics
• Electrical Engineering

Background:

• Simultaneous PET/MR imaging offers combined functional and anatomical insights.
• Integrating PET detectors into MRI RF coils presents electromagnetic interference challenges.

Purpose of the Study:

• To evaluate the impact of an integrated PET/RF head coil system on MRI performance at 3-T.
• To assess the feasibility of using shielded PET detector modules within an MRI RF coil for simultaneous imaging.

Main Methods:

• Developed a PET insert with Cu-shielded detector modules integrated into an 8-element birdcage RF coil.
• Evaluated MRI performance metrics: B0 inhomogeneity, B1 distribution, SAR, and SNR using a phantom.
• Compared MRI performance with and without the integrated PET system.

Main Results:

• Observed a maximum 3μT increase in B0 inhomogeneity and a 5% increase in B1 inhomogeneity in the central transverse plane.
• Reported a 1.21x increase in average SAR and a 1.62x increase in maximum local SAR.
• Noted a significant reduction in SNR (approx. 70% for spin-echo, 60% for gradient-echo) due to shielded PET modules.

Conclusions:

• The integrated PET/RF-coil system demonstrates feasibility for simultaneous PET/MR imaging.
• Despite performance trade-offs, the system can be utilized with existing 3-T MRI scanners.
• Further optimization may mitigate SNR reduction and enhance overall imaging quality.