Fast Imaging Pulse Sequences (Under Construction)#
Modern MRI scanning relies heavily fast imaging pulse sequences, primarily echo-planar imaging (EPI) and Fast/Turbo Spin-echo (FSE/TSE) methods. These allow for multiple k-space lines to be acquired within a single TR.
Learning Goals#
Describe how images are formed
Describe how EPI works
Describe how data is acquired in FSE/TSE sequences
Understand the most popular pulse sequences and their acronyms
Describe how EPI works
Describe how FSE/TSE sequences work
Manipulate MRI sequence parameters to improve performance
Understand how and when to accelerate with EPI
Understand how and when to accelerate with FSE/TSE
Identify artifacts and how to mitigate them
Identify EPI artifacts including distortion and T2*
Identify FSE/TSE artifacts include T2 blurring
Echo-planar Imaging (EPI)#
These pulse sequences readout multiple k-space lines in a row for faster imaging.
Fast/Turbo Spin-echo (FSE/TSE)#
These pulse sequences use multiple spin-echo refocusing pulses after a single exictation pulse. This enables multiple k-space lines to be acquired during the multiple spin-echoes that are formed. This technique was originally called Rapid Acquisition with Relaxation Enhancement (RARE), and is known on various MRI scanners as fast spin-echo (FSE, GE Healthcare), turbo spin-echo (TSE, Siemens Healthineers), or turbo field-echo (TFE, Philips Healthcare).