Mean Squared Error (MSE)-Based Excitation Pattern Design for Parallel Transmit and Receive SENSE MRI Image Reconstruction

Abstract

Parallel coils at both the transmitter and receiver can be used to offer more control over the magnetic resonance imaging (MRI) system, and this implementation has potential to improve the performance in high-field MRI. A new MSE-based EXcitation Pattern (MSE-EXP) design for image reconstruction in parallel transmit and receive SENSitivity Encoding (pTxRx SENSE) MRI is presented in this paper to maximize the performance of an MRI using an array of transmit and receive coils. In the the small-tip-angle regime, we derive theoretically effective excitation patterns for fully-sampled k -space data (with no SNR assumption) and for under-sampled k -space data under both low and high SNR assumptions. The proposed MSE-EXP-encoded pTxRx SENSE MRI has two main advantages for high-field MRI, one is the specific absorption rate (SAR) management through prespecification of the global SAR regulatory limit in the excitation pattern design weight constraint and an another is the imaging acceleration by effective reduction of aliasing artifacts, particularly for advanced image reconstruction in highly under-sampled pTxRx SENSE MRI in the high-SNR regime. Numerical experiments demonstrate that reconstruction accuracy in pTxRx SENSE MRI is significantly improved by the proposed MSE-EXP design, but our study also identifies several practical challenges associated with generation of the proposed MSE-EXP.