Zimu Huo

Zimu Huo

I’m interested in developing advanced data acquisition methods and reconstruction algorithms in magnetic resonance imaging (MRI).

Simulatenous Mulit-slice reconstruction tutorial 1

1 minute read

Published:

Simultaneous Multislice (SMS) is a data acceleration technique that acquires multiple slices at the same time, rather than skipping lines within an acquisition. This method can be visualized as capturing all images within an extended field of view and then undersampling with a slice factor in a simulation. In practice, the signals from all slices are acquired together and superimposed linearly, causing multiple slices to overlap in the final image. The objective of the reconstruction process is to separate these slices with the highest possible quality.

In this simulation of the SMS experiment, we concatenate multiple slices into an extended field of view. Techniques like SENSE and GRAPPA treat this extended field as a single image, applying the reconstruction in their original, unmodified form. However, GRAPPA techniques encounter difficulties in this scenario due to the CAIPI shift causing a phase discontinuity between the images. This sharp change cannot be captured by a small GRAPPA kernel. Since the GRAPPA kernel is small and bandlimited, its image domain representation is smooth and slowly varying, making it inadequate for capturing the sharp phase change.

View the SENSE/GRAPPA tutorial here

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