[HTML][HTML] Increased sensitivity and signal-to-noise ratio in diffusion-weighted MRI using multi-echo acquisitions

C Eichner, M Paquette, T Mildner, T Schlumm, K Pléh… - NeuroImage, 2020 - Elsevier
C Eichner, M Paquette, T Mildner, T Schlumm, K Pléh, L Samuni, C Crockford, RM Wittig
NeuroImage, 2020Elsevier
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) …
Abstract
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.
Elsevier
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