Simultaneous Echo Refocusing EPI (SER-EPI) using Spin Echoes
نویسندگان
چکیده
Fig. 1: General scheme for spin echo based SER-EPI sequence: The standard SER-scheme is extended not only by the refocusing 180 RF-pulse but also by a gradient pulse in phase-encoding direction. This gradient prephasing pulse aligns the gradient echo with the spin echo of the first excitation pulse s1. Fig.2: k-space data of spin-echo based SER-EPI sequence: Phase-encode direction is top to bottom. The position of each spin echo is marked by a dashed line. The temporal distance between those two positions equals the spacing of the excitation
منابع مشابه
Simultaneous spin-echo refocusing.
A new approach to spin-echo imaging is presented in which the 180 degrees RF pulse refocuses two or more spin-echoes at different positions in the readout period. When simultaneous echo refocusing (SER) is implemented using multiple 180 degrees pulses, an undesirable mixing of stimulated echoes and primary echoes from different slices can occur. A novel periodic gradient spoiler scheme eliminat...
متن کامل3D steady-state diffusion-weighted imaging with trajectory using radially batched internal navigator echoes (TURBINE).
While most diffusion-weighted imaging (DWI) is acquired using single-shot diffusion-weighted spin-echo echo-planar imaging, steady-state DWI is an alternative method with the potential to achieve higher-resolution images with less distortion. Steady-state DWI is, however, best suited to a segmented three-dimensional acquisition and thus requires three-dimensional navigation to fully correct for...
متن کاملAccelerated DWI Using Simultaneous Image refocused EPI Optimized for Clinical Imaging
Introduction To reduce imaging times in clinical diffusion imaging, the simultaneous image refocusing (SIR) technique can be utilized to acquire multiple slices in a single readout, thereby shortening the total scan time. With 2 simultaneously refocused echoes, an approximate acceleration factor of 1.5 can be achieved as compared to non-SIR imaging. Multiplexing the slices increases the efficie...
متن کاملMultiplex RARE Dixon: a novel multislice RARE sequence applied to simultaneous slice fat-water Dixon imaging
Introduction Multislice excitation methods have been widely used to increase efficiency in volume coverage. In the simultaneous spin-echo refocusing sequence (SER) [1], two or more slices are excited simultaneously and refocused with a train of 180° pulses which act simultaneously on both slices. However, the SER sequence does not fulfil CPMG conditions, and requires special spoiler gradients t...
متن کاملFaster fat-water imaging with a novel multislice time-shifted GRASE-Dixon sequence
Introduction Recently, the gradientand spin-echo (GRASE) technique has been used to increase efficiency in Dixon fat-water imaging [1,2]. In these sequences, oscillating gradient lobes are carefully positioned between spin refocusing pulses to acquire multiple echoes with the necessary fat-water phase shifts. As it is necessary to collect at least two echoes with approximately π fat-water phase...
متن کامل