Open AccessIn vivo normative atlas of the hippocampal subfields using multi‐echo susceptibility imaging at 7 Tesla
Author(s) -
Goubran Maged,
Rudko David A.,
Santyr Brendan,
Gati Joe,
Szekeres Trevor,
Peters Terry M.,
Khan Ali R.
Publication year - 2014
Publication title -
human brain mapping
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.005
H-Index - 191
eISSN - 1097-0193
pISSN - 1065-9471
DOI - 10.1002/hbm.22423
Subject(s) - hippocampal formation , quantitative susceptibility mapping , voxel , magnetic resonance imaging , atlas (anatomy) , nuclear magnetic resonance , artificial intelligence , pattern recognition (psychology) , nuclear medicine , computer science , neuroscience , physics , medicine , psychology , anatomy , radiology
Objectives: To generate a high‐resolution atlas of the hippocampal subfields using images acquired from 7 T, multi‐echo, gradient‐echo MRI for the evaluation of epilepsy and neurodegenerative disorders as well as investigatingR 2 *(apparent transverse relaxation rate) and quantitative volume magnetic susceptibility (QS) of the subfields. Experimental Design: Healthy control subjects ( n = 17) were scanned at 7 T using a multi‐echo gradient‐echo sequence and susceptibility‐weighted magnitude images,R 2 *and QS maps were reconstructed. We defined a hippocampal subfield labeling protocol for the magnitude image produced from the average of all echoes and assessed reproducibility through volume and shape metrics. A group‐wise diffeomorphic registration procedure was used to generate an average atlas of the subfields for the whole subject cohort. The quantitative MRI maps and subfield labels were then warped to the average atlas space and used to measure mean values ofR 2 *and QS characterizing each subfield. Principal Observations: We were able to reliably label hippocampal subfields on the multi‐echo susceptibility images. The group‐averaged atlas accurately aligns these structures to produce a high‐resolution depiction of the subfields, allowing assessment of both quantitative susceptibility andR 2 *across subjects. Our analysis of variance demonstrates that there are more apparent differences between the subfields on these quantitative maps than the normalized magnitude images. Conclusion: We constructed a high‐resolution atlas of the hippocampal subfields for use in voxel‐based studies and demonstrated in vivo quantification of susceptibility andR 2 *in the subfields. This work is the first in vivo quantification of susceptibility values within the hippocampal subfields at 7 T. Hum Brain Mapp 35:3588–3601, 2014 . © 2013 Wiley Periodicals, Inc.