A cytoarchitecture-driven myelin model reveals area-specific signatures in human primary and secondary areas using ultra-high resolution in-vivo brain MRI

Abstract

This work presents a novel approach for modelling laminar myelin patterns in the human cortex in brain MR images on the basis of known cytoarchitecture. For the first time, it is possible to estimate intracortical contrast visible in quantitative ultra-high resolution MR images in specific primary and secondary cytoarchitectonic areas. The presented technique reveals different area-specific signatures which may help to study the spatial distribution of cortical T1 values and the distribution of cortical myelin in general. It may lead to a new discussion on the concordance of cyto- and myeloarchitectonic boundaries, given the absence of such concordance atlases. The modelled myelin patterns are quantitatively compared with data from human ultra-high resolution in-vivo 7T brain MR images (9 subjects). In the validation, the results are compared to one post-mortem brain sample and its ex-vivo MRI and histological data. Details of the analysis pipeline are provided. In the context of the increasing interest in advanced methods in brain segmentation and cortical architectural studies, the presented model helps to bridge the gap between the microanatomy revealed by classical histology and the macroanatomy visible in MRI.

The developing human connectome project: A minimal processing pipeline for neonatal cortical surface reconstruction

“…Outside of these restrictions, it is important to acknowledge that myelin has been studied long before in the past (Barkovich et al, 1988;Counsell et al, 2002;Prastawa et al, 2005). Fur-thermore, for studies specifically interested in the development of cortical myelin, there exist more advanced methods for sensitising MRI acquisition to myelin content (Borich et al, 2013;Deoni et al, 2011;Dinse et al, 2015;Laule et al, 2008;MacKay and Laule, 2016;Melbourne et al, 2013;Stüber et al, 2014). Some of these in particular, have been shown to be sensitive to developmental changes in myelin (predominantly of the white matter) (Deoni et al, 2011(Deoni et al, , 2015.…”

Studying cyto and myeloarchitecture of the human cortex at ultra-high field with quantitative imaging: R1, R2* and magnetic susceptibility

“…Another segmentation approach would have been automatic segmentation of the subject specific clusters for different quantitative contrasts similar to the functional parcellation of the cortex (Honnorat et al, 2015). The richness of the cortical information attained in these maps opens the door to more advanced co-registration procedures between subjects as well as its segmentation (Dinse et al, 2015). In such approaches both the spatial distribution and the through depth behaviour of the parcellated ROIs could be compared and taken into account during the transformation of the subject specific clusters to the average subject space.…”

How to choose the right MR sequence for your research question at 7 T and above?

“…While at lower fields (3T), R 1 cortical map studies have been based mainly on variable flip angle based methods (Dick et al, 2012;Sereno et al, 2013), at higher field strengths the MP2RAGE sequence has been more commonly used. The latter have achieved 0.6-0.7 mm isotropic resolutions in ~11mins Dinse et al, 2015;Marques et al, 2016;Marques and Gruetter, 2013), while higher resolution protocols at 0.5mm isotropic resolution were acquired in ~30 mins Waehnert et al, 2016) or ~2 hours for 0.35mm protocols (Federau and Gallichan, 2016). It is interesting to note that the details observed in the cortex differ between the different image weightings (T2-w FSE, T1-w MP2RAGE and T2*-w GRE) as illustrated in the last three columns of figure 7.…”