Design of parallel transmission radiofrequency pulses robust against respiration in cardiac MRI at 7 Tesla.

ABSTRACT:

Purpose

Two-spoke parallel transmission (pTX) radiofrequency (RF) pulses have been demonstrated in cardiac MRI at 7T. However, current pulse designs rely on a single set of B1(+)/B0 maps that may not be valid for subsequent scans acquired at another phase of the respiration cycle because of organ displacement. Such mismatches may yield severe excitation profile degradation.

Methods

B1(+)/B0 maps were obtained, using 16 transmit channels at 7T, at three breath-hold positions: exhale, half-inhale, and inhale. Standard and robust RF pulses were designed using maps obtained at exhale only, and at multiple respiratory positions, respectively. Excitation patterns were analyzed for all positions using Bloch simulations. Flip-angle homogeneity was compared in vivo in cardiac CINE ac

SUBMITTER: Schmitter S 

PROVIDER: S-EPMC4437923 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature