Systematic Review of fMRI Compatible Devices: Design and Testing Criteria

Functional Magnetic Resonance Imaging (fMRI) is at present one of the most used methodologies for functional brain exploration, both in clinical and research settings. fMRI can noninvasively measure neural activity by using specific experimental paradigms. Often, these paradigms require the stimulation of the subject to perform sensorimotor tasks: in the past, the stimuli have been administered manually for investigating fundamental aspects of tactile perception and somatosensory processing. Nowadays, the use of mechatronic devices to stimulate the subject during fMRI studies is growing, also to assure reproducibility, control, and monitoring of task performances. For these reasons, researchers are interested in designing interfaces to be used inside the MRI environment during fMRI studies. For the design of every new device safety and compatibility constraints, imposed by the presence of high static magnetic field, switching magnetic gradients and radiofrequency electromagnetic pulses, must be satisfied. Moreover, it should be considered that functional imaging sequences are even more sensitive to perturbations of the magnetic field than MRI standard diagnostic sequences. Despite several existing devices for use in fMRI studies, an extensive review is still lacking. Our survey aims to introduce into the challenges imposed on the development of fMRI-compatible devices. The current state of the art of compatible devices in fMRI will be presented, pointing out the functionalities and peculiarities of various kinds of device. A particular emphasis will be placed on the tests for the evaluation of fMRI compatibility. This review will be useful both for designers of devices to be used in fMRI studies and for neuroscientists that are having to design fMRI experimental paradigm, and therefore require an overview of existing instruments, but also a knowledge of the benefits and criticism arising from their use.