A dedicated PET insert for a 1.5T MR system for simultaneous breast PET/MRI

Ziel/Aim Since the invention of PET, there has always been a need for improving the spatial resolution and system sensitivity of PET systems. Recently, commercial total-body PET/CT systems have been introduced offering 4 x sensitivity for a single organ with a resolution of 3-4 mm. With the EU project HYPMED, we would like to address the above-mentioned needs for breast cancer imaging by developing a PET insert for a clinical 1.5T MRI with a homogeneous spatial resolution of ~1.2 mm with four-fold sensitivity compared standard PET scanners.

Methodik/Methods The insert is designed for simultaneous imaging of PET and 1.5T MRI. It consists of a 4-channel RF receiver coil and two tilted high-resolution PET detector rings. Each detector ring consists of 14x2 detector stacks, resulting in two individual FOVs of about 10 cm height. To ensure a high resolution, a 3-layer crystal array is used. This array is readout by an MR-compatible sensor tile with 144 channels of DPC-3200 (Philips) [1].

Ergebnisse/Results The MRI compatibility of the readout electronics for the entire PET detector system has been investigated with previous defined protocols [2]. B0 disturbance of the detector stacks was reduced to <1ppm in the FOV by choosing non-magnetic components. Furthermore, the PET electronics have been successfully tested for gradient interference. Except for a slight temperature influence on the detector stacks, no data rate losses were observed during highest slew rates and duty cycles of the MRI system. Kinetic mounting of the detector stacks has been chosen, allowing for a precise fixation below 0.1 mm. Flood have been measured and show good crystal identification of the individual layers and crystals. All components of the PET-RF-insert are currently integrated to finalize the design.

Schlussfolgerungen/Conclusions The use of local PET detectors in a standard clinical MRI system is a promising approach for simultaneous multimodal imaging of individual organs with higher sensitivity,improved spatial resolution and an attractive cost range.

• Literatur/References

• 1 Weissler B. et al. IEEE TMI, 34.11 (2015):. 2258-2270.
• 2 Wehner J. et al, Physics in Medicine & Biology, 60 (06) ), p. 2231.

Publication History

Article published online:
08 April 2021