mri backprojection sequence with multiple gradient echoes, especially for diffusionsgewichtetes mri

摘要

In a magnetic resonance imaging apparatus, a subject is disposed in an imaging region (10). A magnet assembly (16, 18) creates a main magnetic field (Bo) through the imaging region (10). A sequence of radio frequency pulses and gradient field manipulations excites and manipulates magnetic resonance within dipoles of the subject. The sequence comprises a 90° RF excitation pulse and a 180° refocusing pulse as is known in the art of standard spin echo imaging. The sequence includes gradient pulses that induce at least two gradient recalled RF echoes (98, 100) while suppressing spin echo signals. The sequence also includes diffusion sensitive gradients (76, 82) that sense the movement of water or other molecules during the imaging sequence. The gradient induced echoes (98, 100) are symmetrically disposed about a time (TE). Included in the apparatus is a reconstruction processor (54) that takes real and imaginary portions of the received magnetic resonance signals and converts them into magnitude data of the signals. The magnitude data is used in lieu of phase encoding in reconstruction.