Radio-Frequency Coil Array for Improved Concurrent Transcranial Magnetic Stimulation and Functional Magnetic Resonance Imaging

Purpose: To perform concurrent TMS-fMRI on difficult targets, such as the occipital lobe. Methods: a 3-channel flexible, thin RF coil was constructed that allows for whole head image coverage without impeding TMS placement. A custom MR-safe patient table which mates with typical 3T MR scanners was constructed for the purpose of face-down subject positioning to allow for access to posterior TMS targets. To counterbalance the loading effect of the TMS coil on the RF coil circuits "Dummy Loads" are introduced, which mimic the loading conditions of the TMS coil when it is not present. Results: the designed RF coil performed as expected, achieving acceptable SNR values at depths equal to the center of the average human head, and high SNR values near the surface. Conclusion: The system allows for concurrent TMS-fMRI, targeting any area of the being while imaging the entire volume.