Myelin and iron concentration in the human brain: A quantitative study of MRI contrast

Stüber, Carsten; Morawski, Markus; Schäfer, Andreas; Labadie, Christian; Wähnert, Miriam; Leuze, Christoph; Streicher, Markus; Barapatre, Nirav; Reimann, Katja; Geyer, Stefan; Spemann, D.; Turner, Robert

doi:10.1016/j.neuroimage.2014.02.026

Cited by 587 publications

(727 citation statements)

References 72 publications

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“…The MP2RAGE sequence allows the acquisition of a quantitative T 1 map and T 1 w image within a reasonable (i.e., <10 min) time frame (Marques et al, 2010). Whereas the T 1 map can be directly used to quantify microstructural (e.g., myelin)‐related changes of the brain (Stuber et al, 2014), the T 1 w image can be readily processed by publicly available software, such as the widely used FreeSurfer, to obtain cortical thickness maps (Fischl & Dale, 2000). However, it has been noted that the quantitative T 1 values using the MP2RAGE sequence, similar to other quantitative T 1 approaches, are affected by

{normalB}_{1}^{-}

and

{normalB}_{1}^{+}

imperfections.…”

Section: Discussionmentioning

confidence: 99%

The impact of correction on MP2RAGE cortical T₁ and apparent cortical thickness at 7T

Haast

Ivanov

Uludağ

2018

Human Brain Mapping

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Determination of cortical thickness using MRI has often been criticized due to the presence of various error sources. Specifically, anatomical MRI relying on T1 contrast may be unreliable due to spatially variable image contrast between gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF). Especially at ultra‐high field (≥ 7T) MRI, transmit and receive B1‐related image inhomogeneities can hamper correct classification of tissue types. In the current paper, we demonstrate that residual normalB1+ (transmit) inhomogeneities in the T1‐weighted and quantitative T1 images using the MP2RAGE sequence at 7T lead to biases in cortical thickness measurements. As expected, post‐hoc correction for the spatially varying normalB1+ profile reduced the apparent T1 values across the cortex in regions with low normalB1+, and slightly increased apparent T1 in regions with high normalB1+. As a result, improved contrast‐to‐noise ratio both at the GM‐CSF and GM‐WM boundaries can be observed leading to more accurate surface reconstructions and cortical thickness estimates. Overall, the changes in cortical thickness ranged between a 5% decrease to a 70% increase after normalB1+ correction, reducing the variance of cortical thickness values across the brain dramatically and increasing the comparability with normative data. More specifically, the cortical thickness estimates increased in regions characterized by a strong decrease of apparent T1 after normalB1+ correction in regions with low normalB1+ due to improved detection of the pial surface. The current results suggest that cortical thickness can be more accurately determined using MP2RAGE data at 7T if normalB1+ inhomogeneities are accounted for.

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{normalB}_{1}^{-}

and

{normalB}_{1}^{+}

imperfections.…”

Section: Discussionmentioning

confidence: 99%

The impact of correction on MP2RAGE cortical T₁ and apparent cortical thickness at 7T

Haast

Ivanov

Uludağ

2018

Human Brain Mapping

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“…15, 38 Limitations in the validity of this assumption may be a source of bias. Models such as the one presented here are also a first step towards in vivo histology,2 in which quantitative maps are combined using biophysical models in order to extract descriptors of the underlying tissue such as myelin and iron levels3 or the degree of myelination of fibres 48. Any biases present in the parameter maps derived from this model would propagate through to these biological descriptors.…”

Section: Discussionmentioning

confidence: 99%

“…However, since qMRI metrics are sensitive to multiple biological factors (e.g. fibre density, water, myelin and iron content), multiple parameters are needed to improve biological specificity 3. The multi‐parameter mapping (MPM) protocol1 is one such quantitative imaging approach, in which data are combined to calculate maps of the longitudinal relaxation rate ( R 1 ), the effective transverse relaxation rate ( R 2 *), the magnetization transfer saturation (MT) and the effective proton density (PD*).…”

Section: Introductionmentioning

confidence: 99%

Synthetic quantitative MRI through relaxometry modelling

2016

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Quantitative MRI (qMRI) provides standardized measures of specific physical parameters that are sensitive to the underlying tissue microstructure and are a first step towards achieving maps of biologically relevant metrics through in vivo histology using MRI. Recently proposed models have described the interdependence of qMRI parameters. Combining such models with the concept of image synthesis points towards a novel approach to synthetic qMRI, in which maps of fundamentally different physical properties are constructed through the use of biophysical models. In this study, the utility of synthetic qMRI is investigated within the context of a recently proposed linear relaxometry model. Two neuroimaging applications are considered. In the first, artefact‐free quantitative maps are synthesized from motion‐corrupted data by exploiting the over‐determined nature of the relaxometry model and the fact that the artefact is inconsistent across the data. In the second application, a map of magnetization transfer (MT) saturation is synthesized without the need to acquire an MT‐weighted volume, which directly leads to a reduction in the specific absorption rate of the acquisition. This feature would be particularly important for ultra‐high field applications. The synthetic MT map is shown to provide improved segmentation of deep grey matter structures, relative to segmentation using T 1‐weighted images or R 1 maps. The proposed approach of synthetic qMRI shows promise for maximizing the extraction of high quality information related to tissue microstructure from qMRI protocols and furthering our understanding of the interrelation of these qMRI parameters.

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“…T1-und MT-Karten wurden auch als Marker für die kortikale Myelinisierung verwendet [3,13,67,68]. Die T1-Myelinkarten zeigten nicht nur einen ähnlichen kortikalen Verlauf wie aus der Myelinfärbung mittels Ex-vivo-Histologie bekannt [67], sondern zeigten auch einen Struktur-Funktions-Zusammenhang zwischen der Myelinisierung und der funktionellen Aktivierung in der primären visuellen [67] …”

Section: » Vorteil Der Qmrt-daten Gegenüber Der Mrt Ist Ihre Verbesseunclassified

“…Darüber hinaus ermöglicht die sog. biophysikalische Modellierung des MRT-Signals die Messung mikroskopischer Hirngewebeinformationen, wie beispielsweise die Verteilung von axonalen Durchmessern [2] oder Eisen-und Myelindichten [3]. Dieses neue Feld innerhalb der computationalen Neuroanatomie eröffnet damit ein Fenster auf die Mikrostruktur ähnlich wie die Histologie und wird daher auch In-vivo-Histologie mittels MRT oder hMRT (.…”

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Computationale Neuroanatomie und Mikrostrukturbildgebung mit der Magnetresonanztomographie

Mohammadi

Weiskopf

2017

Nervenarzt

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Myelin and iron concentration in the human brain: A quantitative study of MRI contrast

Cited by 587 publications

References 72 publications

The impact of correction on MP2RAGE cortical T₁ and apparent cortical thickness at 7T

The impact of correction on MP2RAGE cortical T₁ and apparent cortical thickness at 7T

Synthetic quantitative MRI through relaxometry modelling

Computationale Neuroanatomie und Mikrostrukturbildgebung mit der Magnetresonanztomographie

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Myelin and iron concentration in the human brain: A quantitative study of MRI contrast

Cited by 587 publications

References 72 publications

The impact of correction on MP2RAGE cortical T1 and apparent cortical thickness at 7T

The impact of correction on MP2RAGE cortical T1 and apparent cortical thickness at 7T

Synthetic quantitative MRI through relaxometry modelling

Computationale Neuroanatomie und Mikrostrukturbildgebung mit der Magnetresonanztomographie

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The impact of correction on MP2RAGE cortical T₁ and apparent cortical thickness at 7T

The impact of correction on MP2RAGE cortical T₁ and apparent cortical thickness at 7T