Time-efficient and flexible design of optimized multishell HARDI diffusion.

Jana Hutter,Jesper Andersson,Saad Jbabdi,Shaihan Malik,Stamatios N Sotiropoulos,A David Edwards,Emer J Hughes,Joseph V Hajnal,Johannes Steinweg,Matteo Bastiani,Anthony N Price,Lucilio Cordero‐Grande,J Donald Tournier

doi:10.1002/mrm.26765

Abstract

PurposeAdvanced diffusion magnetic resonance imaging benefits from collecting as much data as is feasible but is highly sensitive to subject motion and the risk of data loss increases with longer acquisition times. Our purpose was to create a maximally time‐efficient and flexible diffusion acquisition capability with built‐in robustness to partially acquired or interrupted scans. Our framework has been developed for the developing Human Connectome Project, but different application domains are equally possible.MethodsComplete flexibility in the sampling of diffusion space combined with free choice of phase‐encode‐direction and the temporal ordering of the sampling scheme was developed taking into account motion robustness, internal consistency, and hardware limits. A split‐diffusion‐gradient preparation, multiband acceleration, and a restart capacity were added.ResultsThe framework was used to explore different parameters choices for the desired high angular resolution diffusion imaging diffusion sampling. For the developing Human Connectome Project, a high‐angular resolution, maximally time‐efficient (20 min) multishell protocol with 300 diffusion‐weighted volumes was acquired in >400 neonates. An optimal design of a high‐resolution (1.2 × 1.2 mm2) two‐shell acquisition with 54 diffusion weighted volumes was obtained using a split‐gradient design.ConclusionThe presented framework provides flexibility to generate time‐efficient and motion‐robust diffusion magnetic resonance imaging acquisitions taking into account hardware constraints that might otherwise result in sub‐optimal choices. Magn Reson Med 79:1276–1292, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Highlights

Diffusion magnetic resonance imaging is able to provide insight into the complex neural fibre tract architecture of the human brain in vivo [1]
The created modified Diffusion magnetic resonance imaging (dMRI) acquisition is highly flexible and can be used to design quite different acquisitions depending on priorities and hardware constraints
Key design requirements for developing Human Connectome Project (dHCP) are: total TA of 20 min, minimal imaged volume for the target population set at 145 Â 120 Â 96 mm3 which is sufficient for up to the 95th percentile for head size at 44 weeks gestational age, and a high angular resolution diffusion imaging (HARDI) prescription having four shells (b0, b400, b1000, b2600) with a distribution of 5:16:22:32 volumes per shell that was optimized for the neonatal brain

Summary

Introduction

Diffusion magnetic resonance imaging (dMRI) is able to provide insight into the complex neural fibre tract architecture of the human brain in vivo [1]. It has clinical applications in the study, diagnosis and treatment of neurological disorders [2], as well as many scientifically focused applications, with an important emerging focus on building comprehensive models of human brain connectivity [3,4]. The acquired dMRI data, using specific gradients with varying magnitude and direction that introduce sensitivity to water diffusive processes of molecules in the brain, provide the input to the chosen analysis pipeline and determine and limit its capacity to probe structural complexity of the human brain.

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Discussion

Conclusion