From simultaneous to synergistic MR-PET brain imaging: A review of hybrid MR-PET imaging methodologies

Abstract

Simultaneous Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) scanning is a recent major development in biomedical imaging. The full integration of the PET detector ring and electronics within the MR system has been a technologically challenging design to develop but provides capacity for simultaneous imaging and the potential for new diagnostic and research capability. This article reviews state-of-the-art MR-PET hardware and software, and discusses future developments focusing on neuroimaging methodologies for MR-PET scanning. We particularly focus on the methodologies that lead to an improved synergy between MRI and PET, including optimal data acquisition, PET attenuation and motion correction, and joint image reconstruction and processing methods based on the underlying complementary and mutual information. We further review the current and potential future applications of simultaneous MR-PET in both systems neuroscience and clinical neuroimaging research. We demonstrate a simultaneous data acquisition protocol to highlight new applications of MR-PET neuroimaging research studies.

Keywords: MR-PET; PET/MR; attenuation correction; dynamic FDG-PET; functional MRI; joint image reconstruction; motion.

Figure 1

Data flow in simultaneous MR‐PET imaging. The following modules are unique to the dual modality: MR based AC; MR derived motion parameters; joint MR‐PET image reconstruction

Figure 2

Simultaneous BOLD‐fMRI/FDG‐fPET activation using a checkboard visual stimulation in a single subject (adapted from Li et al., 2018). Consistent with the results of (Wehrl et al., 2013) in the rat, the results from the two modalities are comparable, but with more focused activity in the FDG‐fPET than BOLD‐fMRI data [Color figure can be viewed at http://wileyonlinelibrary.com]