Numerical and experimental investigation of the causes and thresholds of magnetophosphenes induced by magnetic resonance imaging gradient switching

• Applicant: Dr. Valerie Klein
• Subject Area: Medical Physics, Biomedical Technology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 519309174

Magnetophosphenes are visual stimuli produced by stimulation of electrically excitable cells in the retina. In MRI, phosphenes can occur due to electric fields induced by switching gradient fields. The goal of this research is to study magnetophosphenes by developing a detailed simulation pipeline for predicting phosphenes and by conducting an experimental study in which the threshold for magnetophosphene generation is measured in human volunteers. The mechanisms underlying magnetophosphenes are not well understood to date. Some of the open questions that will be answered by this research project are what type of excitable cells in the retina are stimulated by the induced E-fields and what mechanisms underlie the observed frequency dependence of magnetophosphene thresholds. By examining the magnetophosphene thresholds of different MRI gradient systems, this work will help define safe limits for the operation of whole-body and head MRI gradient systems. Detailed and validated simulations of magnetophosphenes will serve as a basis for developing strategies to minimize the occurrence of phosphenes in MRI, e.g., by optimizing gradient coils or sequence designs. The goal of this research is to avoid the induction of phosphenes in MRI altogether, thereby reducing gradient performance limitations that are particularly relevant for long gradient rise times (such as those used in diffusion imaging).

• DFG Programme: Research Grants
• International Connection: USA
• Co-Investigator: Professor Dr. Lothar Rudi Schad
• Cooperation Partners: Dr. Mathias Davids; Professor Dr. Bastien Guerin; Professor Dr. Lawrence Wald