Iowa State University researchers have developed a novel coil, namely Quadruple Butterfly Coil (QBC). This device has improved significant higher focality over the commercial Figure of Eight (FOE) coils with decreased stimulated area in brain. Model simulation results indicated that QBC stimulates a localized area of the brain, which minimized the stimulation of surrounding neural networks.
Transcranial Magnetic Stimulation (TMS) is a widely used technique for the investigation of stimulation responses of the brain which has proven to have therapeutic effects for neurological disorders such as traumatic brain injury, Parkinson’s disease and post-traumatic stress disorder (PTSD). There have been many coils designed in the last twenty years due to TMS’ popularity, but no coils have shown significant improvement in focality over the commercial Figure of Eight (FOE) coils, while maintaining the field intensity required to stimulate at the depth of the surface of the brain.
Iowa State University researchers designed a new coil, Quadruple Butterfly Coil (QBC) with an improved double coil with two sets of coils. This new coil achieved a finer resolution for stimulation, with decreased stimulation volume over the cortex, while without deeper brain stimulation. QBC has been compared with commercial FOE coils using 50 anatomically realistic heterogeneous MRI derived head models, and results shows QBC has a significant improvement in focality over FOE with decreased stimulation area by approximately 1/3.
Lately, QBC performance for the application of Schizophrenic patients has been simulated at Magnetics Research Group at ISU. Preliminary results demonstrated the QBC provides a lightly weaker field, but has more focal over the FOE coils. Specifically, the volume stimulated above 50% the local maximum was 30x greater in the FOE.