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  Flexible proton density (PD) mapping using multi-contrast variable flip angle (VFA) data

Lorio, S., Tierney, T. M., McDowell, A., Arthurs, O. J., Lutti, A., Weiskopf, N., et al. (2019). Flexible proton density (PD) mapping using multi-contrast variable flip angle (VFA) data. NeuroImage, 186, 464-475. doi:10.1016/j.neuroimage.2018.11.023.

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Item Permalink: http://hdl.handle.net/21.11116/0000-0002-9776-F Version Permalink: http://hdl.handle.net/21.11116/0000-0003-CAB0-2
Genre: Journal Article

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 Creators:
Lorio, Sara1, Author
Tierney, Tim M.2, Author
McDowell, Amy1, Author
Arthurs, Owen J.1, 3, Author
Lutti, Antoine4, Author
Weiskopf, Nikolaus5, Author              
Carmichael, David W.1, 6, Author
Affiliations:
1UCL Great Ormond Street Institute of Child Health, University College London, United Kingdom, ou_persistent22              
2Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, United Kingdom, ou_persistent22              
3Department of Radiology, UCL Great Ormond Street Institute of Child Health, University College London, United Kingdom, ou_persistent22              
4Département des Neurosciences Cliniques, Laboratoire de Recherche en Neuroimagerie (LREN), Centre hospitalier universitaire vaudois, Lausanne, Switzerland, ou_persistent22              
5Department Neurophysics (Weiskopf), MPI for Human Cognitive and Brain Sciences, Max Planck Society, ou_2205649              
6Centre for Medical Engineering, King’s College London, United Kingdom, ou_persistent22              

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Free keywords: Quantitative MRI; Proton density; Biophysical tissue properties; Anatomical malformation; Post-mortem MRI
 Abstract: Quantitative proton density (PD) maps measure the amount of free water, which is important for non-invasive tissue characterization in pathology and across lifespan. PD mapping requires the estimation and subsequent removal of factors influencing the signal intensity other than PD. These factors include the T1, T2* relaxation effects, transmit field inhomogeneities, receiver coil sensitivity profile (RP) and the spatially invariant factor that is required to scale the data. While the transmit field can be reliably measured, the RP estimation is usually based on image post-processing techniques due to limitations of its measurement at magnetic fields higher than 1.5 T. The post-processing methods are based on unified bias-field/tissue segmentation, fitting the sensitivity profile from images obtained with different coils, or on the linear relationship between T1 and PD. The scaling factor is derived from the signal within a specific tissue compartment or reference object. However, these approaches for calculating the RP and scaling factor have limitations particularly in severe pathology or over a wide age range, restricting their application. We propose a new approach for PD mapping based on a multi-contrast variable flip angle acquisition protocol and a data-driven estimation method for the RP correction and map scaling. By combining all the multi-contrast data acquired at different echo times, we are able to fully correct the MRI signal for T2* relaxation effects and to decrease the variance and the entropy of PD values within tissue class of the final map. The RP is determined from the corrected data applying a non-parametric bias estimation, and the scaling factor is based on the median intensity of an external calibration object. Finally, we compare the signal intensity and homogeneity of the multi-contrast PD map with the well-established effective PD (PD*) mapping, for which the RP is based on concurrent bias field estimation and tissue classification, and the scaling factor is estimated from the mean white matter signal. The multi-contrast PD values homogeneity and accuracy within the cerebrospinal fluid (CSF) and deep brain structures are increased beyond that obtained using PD* maps. We demonstrate that the multi-contrast RP approach is insensitive to anatomical or a priori tissue information by applying it in a patient with extensive brain abnormalities and for whole body PD mapping in post-mortem foetal imaging.

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Language(s): eng - English
 Dates: 2018-11-132018-04-202018-11-162018-11-192019-02-01
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: Peer
 Identifiers: DOI: 10.1016/j.neuroimage.2018.11.023
PMID: 30465865
Other: Epub 2018
 Degree: -

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Project name : Entschlüsselung der pathophysiologischen Prozesse induziert durch eine Querschnittlähmung: Anwendung von MRT basierter in vivo und ex vivo Histologie / hMRIofSCI
Grant ID : 01EW1711B
Funding program : ERA-NET NEURON
Funding organization : German Federal Ministry of Education and Research (BMBF)
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Funding organization : Department of Health, Australian Government
Project name : Antibodies against Nogo-A to enhance plasticity, regeneration and functional recovery after acute spinal cord injury, a multicenter European clinical proof of concept trial / NISCI
Grant ID : 681094
Funding program : Horizon 2020
Funding organization : European Commission (EC)
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Grant ID : 15.0137
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Funding organization : Swiss State Secretariat for Education, Research and Innovation (SERI)
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Grant ID : GN2214
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Funding organization : Henry Smith Charity and Action Medical Research
Project name : Non-invasive in vivo histology in health and disease using Magnetic Resonance Imaging (MRI) / HMRI
Grant ID : 616905
Funding program : Funding Programme 7
Funding organization : European Commission (EC)
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Grant ID : -
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Funding organization : NIHR GOSH Biomedical Research Centre
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Grant ID : NIHR-CS-012-002
Funding program : Clinician Scientist Fellowship Award
Funding organization : National Institute for Health Research (NIHR)
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Funding organization : Great Ormond Street Hospital Children's Charity
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Funding program : -
Funding organization : NIHR GOSH Biomedical Research Centre
Project name : -
Grant ID : 203148/Z/16/Z
Funding program : -
Funding organization : Wellcome/EPSRC Centre for Medical Engineering

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Title: NeuroImage
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: Orlando, FL : Academic Press
Pages: - Volume / Issue: 186 Sequence Number: - Start / End Page: 464 - 475 Identifier: ISSN: 1053-8119
CoNE: https://pure.mpg.de/cone/journals/resource/954922650166