Multimodal imaging: Simultaneous EEG in a 3T Hybrid MR–PET system

Abstract The new generation of integrated MR–PET systems allows the simultaneous acquisition of MR and PET data. While MR delivers structural data with an excellent spatial resolution, the advantage of PET is its information on a molecular level. However, both modalities have a low temporal resolution. Thus, for pharmacological studies or patients who suffer from treatment resistant epilepsy the combination of yet another modality such as EEG could be desirable. We tested the feasibility of evoked visual potentials in a 3T Hybrid MR–PET system (Siemens Germany) in comparison to a standalone 3T Trio System (Siemens Germany). A T2⁎-weighted EPI sequence was used: TR: 2.2 s, TE: 30 ms, FOV: 200 mm, slice thickness 3, 36 slices in a healthy volunteer (male, 27 years old) using an MR-compatible 32-channel EEG system (Brainproducts, Munich, Germany). We applied 200 trials of visual stimulation from a white and black checkerboard. Visual evoked potentials were analyzed using Brain Vision Analyzer (Brainproducts, Munich, Germany). Gradient correction and cardioballistic artefact correction were performed as implemented in Vision Analyzer. Visual event related potentials were successfully recorded at the 3T Hybrid MR–PET system. Both curves differ slightly in shape and latency due to the following factors: the distance from the screen varies slightly and the size of the field of view of the subjects is smaller in the 3T MR–PET system in comparison to the 3T stand alone system. Extending the 3T MR–PET Hybrid system to 3T Hybrid MR–PET–EEG is feasible and adds another tool to clinical neuroimaging and research.