Three-dimensional Fourier encoding of simultaneously excited slices: generalized acquisition and reconstruction...

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Medical Imaging Physics

Background:

• Simultaneous multislice (SMS) acquisitions accelerate imaging by combining single-shot sampling with slice-dimension acceleration.
• Current 2D descriptions of SMS sampling and reconstruction are established but limited.
• Three-dimensional (3D) volumetric acquisitions were previously required for slice acceleration.

Purpose of the Study:

• To present a generalized 3D Fourier encoding and reconstruction formalism for SMS acquisitions.
• To extend SMS methods to non-Cartesian sampling and reconstruction.
• To provide a unified framework applicable to various SMS acquisition types.

Main Methods:

• Defined an "SMS 3D" k-space where the field of view in the slice direction accommodates multiple slices.
• Viewed SMS acceleration as undersampling within this 3D k-space, allowing flexible distribution between in-plane and slice directions.
• Demonstrated reconstruction using SMS sensitivity encoding and non-Cartesian SMS imaging with blipped spiral trajectories.

Main Results:

• Successfully applied the SMS 3D k-space formalism to phantom and in vivo brain imaging.
• Included data acquired with blipped-controlled aliasing in parallel imaging (CAIPI) sampling.
• Demonstrated SMS sensitivity encoding reconstruction and non-Cartesian SMS imaging.

Conclusions:

• The 3D k-space approach enables the full framework of reconstruction methods for SMS acquisitions.
• Blipped-CAIPI is a specific instance of undersampling the SMS 3D k-space.
• Extending SMS methods to non-Cartesian 3D sampling and reconstruction is straightforward.