Newly, improve integration concepts for hybridization of positron emission tomography and magnetic resonance imaging

• Applicant: Professor Dr.-Ing. Volkmar Schulz
• Subject Area: Medical Physics, Biomedical Technology
• Term: from 2016 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 288267690

The combination of positron emission tomography (PET) with its high sensitivity and magnetic resonance imaging (MRI), providing high quality anatomic information, enables advanced preclinical as well as clinical research. For the best possible quality achievable with such a hybrid device, image acquisition of PET and MRI have to be performed simultaneously which results in a better spatial and temporal co-registration of datasets enabling also applications such as motion compensation. However, integrating both modalities into a hybrid device enabling such a simultaneous acquisition is considered to be a challenging task since both devices are expected to interact with each other. In the recent years several combined PET/MRI prototypes have been developed. All solutions presented so far still suffer from spatial compromises necessary to integrate the PET detector inside an MRI system's bore. Besides reducing the available FOV, the spatial constraint limits the performance of both imaging devices: In particular the sensitivity on the PET side and the signal-to-noise performance on the MRI side. As a consequence we propose to investigate an integration concept in which the PET detector's scintillation crystals are incorporated into the RF coil of the MRI namely into an otherwise unused space between the RF resonator and its surrounding RF screen. Hence this space can be enlarged in comparison to conventional approaches, significant improvements of the MRI's SNR as well as PET's sensitivity can be realized. To enable such an advanced incorporation, a plurality of research questions needed to be answered carefully which are targeted by the proposed research project.As a target scenario, we aim at the integration of our fully digital PET/MRI readout platform, using a digital version of Silicon Photomultipliers, into a preclinical small-bore MRI system (Bruker BioSpic 7020 USR). In order to address the integration task systematically, two demonstrators are being developed. With the first demonstrator the optical properties of a combined light guide/RF screening technology and its impact on the PET performance like crystal identification or energy resolution will be investigated. The second demonstrator will serve as a research platform to investigate the suitability of different RF screening materials or geometries/topologies and the consequences for the SNR performance of the RF coil. The development and evaluation of both demonstrators will be performed iteratively yielding two demonstrators which will be finally combined into a hybrid demonstrator. This hybrid demonstrator will be used to study the PET and MRI performance under simultaneous acquisition conditions and will allow a comprehensive assessment of the technologies developed within this projects enabling future highly integrated PET/MRI systems for preclinical as well as clinical applications.

• DFG Programme: Research Grants
• Cooperation Partners: Professor Dr. Bernhard Blümich; Professor Dr.-Ing. Dirk Heberling