Increased sensitivity and signal-to-noise ratio in diffusion-weighted MRI using multi-echo acquisitions
Cornelius Eichner,
Michael Paquette,
Toralf Mildner,
Torsten Schlumm,
Kamilla Pléh,
Liran Samuni,
Catherine Crockford,
Roman M. Wittig,
Carsten Jäger,
Harald E. Möller,
Angela D. Friederici,
Alfred Anwander
Affiliations
Cornelius Eichner
Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neuropsychology, Leipzig, Germany; Corresponding author.
Michael Paquette
Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neuropsychology, Leipzig, Germany
Toralf Mildner
Max Planck Institute for Human Cognitive and Brain Sciences, NMR Group, Leipzig, Germany
Torsten Schlumm
Max Planck Institute for Human Cognitive and Brain Sciences, NMR Group, Leipzig, Germany
Kamilla Pléh
Robert Koch Institute, Epidemiology of Highly Pathogenic Microorganisms, Berlin, Germany; Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
Liran Samuni
Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire; Harvard University, Department of Human Evolutionary Biology, Cambridge, MA, United States
Catherine Crockford
Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire; Max Planck Institute for Evolutionary Anthropology, Department of Human Behavior, Ecology and Culture, Leipzig, Germany
Roman M. Wittig
Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire; Max Planck Institute for Evolutionary Anthropology, Department of Human Behavior, Ecology and Culture, Leipzig, Germany
Carsten Jäger
Paul Flechsig Institute for Brain Research, University of Leipzig, Germany; Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neurophysics, Leipzig, Germany
Harald E. Möller
Max Planck Institute for Human Cognitive and Brain Sciences, NMR Group, Leipzig, Germany
Angela D. Friederici
Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neuropsychology, Leipzig, Germany
Alfred Anwander
Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neuropsychology, Leipzig, Germany
Post-mortem diffusion MRI (dMRI) enables acquisitions of structural imaging data with otherwise unreachable resolutions - at the expense of longer scanning times. These data are typically acquired using highly segmented image acquisition strategies, thereby resulting in an incomplete signal decay before the MRI encoding continues. Especially in dMRI, with low signal intensities and lengthy contrast encoding, such temporal inefficiency translates into reduced image quality and longer scanning times. This study introduces Multi Echo (ME) acquisitions to dMRI on a human MRI system - a time-efficient approach, which increases SNR (Signal-to-Noise Ratio) and reduces noise bias for dMRI images. The benefit of the introduced ME-dMRI method was validated using numerical Monte Carlo simulations and showcased on a post-mortem brain of a wild chimpanzee. The proposed Maximum Likelihood Estimation echo combination results in an optimal SNR without detectable signal bias. The combined strategy comes at a small price in scanning time (here 30% additional) and leads to a substantial SNR increase (here white matter: ~ 1.6x, equivalent to 2.6 averages, grey matter: ~ 1.9x, equivalent to 3.6 averages) and a general reduction of the noise bias.
