Keywords: RF Pulse Design & Fields, Brain
Motivation: Contrast in high-field MRI is obscured by the spatially non-uniform excitation flip angle profile of conventional birdcage transmit coils.
Goal(s): We demonstrate that a single $$$B_z$$$ coil operated in the kHz range can supplement a birdcage to create a spatially-uniform flip angle profile using multiphoton excitation.
Approach: We use a stream function boundary element method to optimize the $$$B_z$$$ coil windings to produce homogeneous nonselective multiphoton excitations across a universal pulse database and validate with Bloch simulations.
Results: The single $$$B_z$$$ channel achieved a mean flip angle NRMSE of 13.9% for a 90º target MP-pTx pulse in test subjects.
Impact: The design method provides a simplified hardware configuration and reduced local SAR concerns compared to either conventional pTx or our previous work using a full shim array in conjunction with multiphoton parallel transmission.
How to access this content:
For one year after publication, abstracts and videos are only open to registrants of this annual meeting. Registrants should use their existing login information. Non-registrant access can be purchased via the ISMRM E-Library.
After one year, current ISMRM & ISMRT members get free access to both the abstracts and videos. Non-members and non-registrants must purchase access via the ISMRM E-Library.
After two years, the meeting proceedings (abstracts) are opened to the public and require no login information. Videos remain behind password for access by members, registrants and E-Library customers.
Keywords