TY - JOUR
T1 - A Diffeomorphic Vector Field Approach to Analyze the Thickness of the Hippocampus from 7 T MRI
AU - Guyot, Alexis
AU - Fouquier, Ana B.Graciano
AU - Gerardin, Emilie
AU - Chupin, Marie
AU - Glaunes, Joan A.
AU - Marrakchi-Kacem, Linda
AU - Germain, Johanne
AU - Boutet, Claire
AU - Cury, Claire
AU - Hertz-Pannier, Lucie
AU - Vignaud, Alexandre
AU - Durrleman, Stanley
AU - Henry, Thomas R.
AU - Van De Moortele, Pierre Francois
AU - Trouve, Alain
AU - Colliot, Olivier
N1 - Publisher Copyright:
© 1964-2012 IEEE.
PY - 2021/2
Y1 - 2021/2
N2 - Objective: 7-Tesla MRI of the hippocampus enhances the visualization of its internal substructures. Among these substructures, the cornu Ammonis and subiculum form a contiguous folded ribbon of gray matter. Here, we propose a method to analyze local thickness measurements of this ribbon. Methods: We introduce an original approach based upon the estimation of a diffeomorphic vector field that traverses the ribbon. The method is designed to handle specificities of the hippocampus and corresponding 7-Tesla acquisitions: highly convoluted surface, non-closed ribbon, incompletely defined inner/outer boundaries, anisotropic acquisitions. We furthermore propose to conduct group comparisons using a population template built from the central surfaces of individual subjects. Results: We first assessed the robustness of our approach to anisotropy, as well as to inter-rater variability, on a post-mortem scan and on in vivo acquisitions respectively. We then conducted a group study on a dataset of in vivo MRI from temporal lobe epilepsy (TLE) patients and healthy controls. The method detected local thinning patterns in patients, predominantly ipsilaterally to the seizure focus, which is consistent with medical knowledge. Conclusion: This new technique allows measuring the thickness of the hippocampus from 7-Tesla MRI. It shows good robustness with respect to anisotropy and inter-rater variability and has the potential to detect local atrophy in patients. Significance: As 7-Tesla MRI is increasingly available, this new method may become a useful tool to study local alterations of the hippocampus in brain disorders. It is made freely available to the community (code: https://github.com/aramis-lab/hiplay7-thickness, postmortem segmentation: https://doi.org/10.5281/zenodo.3533264).
AB - Objective: 7-Tesla MRI of the hippocampus enhances the visualization of its internal substructures. Among these substructures, the cornu Ammonis and subiculum form a contiguous folded ribbon of gray matter. Here, we propose a method to analyze local thickness measurements of this ribbon. Methods: We introduce an original approach based upon the estimation of a diffeomorphic vector field that traverses the ribbon. The method is designed to handle specificities of the hippocampus and corresponding 7-Tesla acquisitions: highly convoluted surface, non-closed ribbon, incompletely defined inner/outer boundaries, anisotropic acquisitions. We furthermore propose to conduct group comparisons using a population template built from the central surfaces of individual subjects. Results: We first assessed the robustness of our approach to anisotropy, as well as to inter-rater variability, on a post-mortem scan and on in vivo acquisitions respectively. We then conducted a group study on a dataset of in vivo MRI from temporal lobe epilepsy (TLE) patients and healthy controls. The method detected local thinning patterns in patients, predominantly ipsilaterally to the seizure focus, which is consistent with medical knowledge. Conclusion: This new technique allows measuring the thickness of the hippocampus from 7-Tesla MRI. It shows good robustness with respect to anisotropy and inter-rater variability and has the potential to detect local atrophy in patients. Significance: As 7-Tesla MRI is increasingly available, this new method may become a useful tool to study local alterations of the hippocampus in brain disorders. It is made freely available to the community (code: https://github.com/aramis-lab/hiplay7-thickness, postmortem segmentation: https://doi.org/10.5281/zenodo.3533264).
KW - 7-Tesla
KW - Diffeomorphism
KW - Hippocampus
KW - Magnetic Resonance Imaging
KW - Morphometry
KW - Thickness
KW - Ultra-high-field
UR - http://www.scopus.com/inward/record.url?scp=85099883057&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85099883057&partnerID=8YFLogxK
U2 - 10.1109/TBME.2020.2999941
DO - 10.1109/TBME.2020.2999941
M3 - Article
C2 - 32746019
AN - SCOPUS:85099883057
SN - 0018-9294
VL - 68
SP - 393
EP - 403
JO - IEEE Transactions on Biomedical Engineering
JF - IEEE Transactions on Biomedical Engineering
IS - 2
M1 - 9108539
ER -