Technical considerations of functional MRI in deep brain stimulation: recent advances and future perspectives

Magnetic resonance imaging (MRI) is a valuable clinical and research tool for patients managed using deep brain stimulation (DBS). Unfortunately, MRI under these conditions is associated with substantial risks, necessitating stringent regulations that limit its clinical and research utility. In addition, magnetic susceptibility differences between DBS hardware and surrounding tissues significantly compromise spatial encoding mechanisms of conventional MRI sequences, resulting in image signal loss and geometric distortions. The impact on gradient-recalled echo echo-planar imaging sequences commonly utilised for functional MRI in DBS settings is particularly severe. This review presents a range of mitigation strategies aimed at both safety and enhanced image quality, spanning innovations in DBS hardware design to advanced MRI sequences capable of addressing issues inherent to the presence of DBS hardware, such as electrode heating and susceptibility artefacts. Additionally, we highlight approaches incorporating the discussed novel postprocessing techniques and functional MRI acquisition protocols, along with their limitations and associated challenges to enable their wider dissemination, with the overarching objective of improving the quality of life of DBS patients.