The overall aim of this group is to develop a candidate protocol for segmentation of hippocampal and parahippocampal subregions applicable to in vivo human imaging, which would facilitate a direct comparison between the results obtained from different labs.
This is an open working group and we therefore invite anyone who is interested to join and encourage feedback on this effort. The more input we get from various fields (anatomists, ex vivo imagers, and in vivo imagers across a range of field strengths), the better!
As a first step, we have decided to focus on subfield segmentation in the body of the hippocampus using 3T MRI, before moving to the head and tail sections. Upon completion of the 3T harmonized protocol, it will be adjusted for other applications, such as 7T structural images, which may involve adding more granular rules on top of the 3T protocol.
The Boundary Working Group itself is composed of several smaller working groups and a steering committee (Ana Daugherty, Renaud La Joie, Rosanna Olsen, Laura Wisse).
The harmonized protocol must achieve anatomical validity confirmed by histological reference materials.
Existing segmentation protocols are based on a variety of pre-existing histology atlases, which may in part have contributed to the variability amongst imaging protocols. Also, these atlases usually describe one individual and show a limited number of slices along the anterior-posterior length of the hippocampus while the angulation of histology samples commonly differs from the orientation of MRI. To resolve this, we aim at gathering several histology samples from different pathology labs. This unique and comprehensive atlas set will optimize the anatomical validity of the final harmonized protocol.
Members of the Outer Boundary Group include Ricardo Insausti, Jean Augustinack, Katrin Amunts & Olga Kedo.
Body ranging Group
As a first step of harmonized protocol development, we will start with the body of the hippocampus.
This specific working group aims at developing and testing specific rules to reliably determine which slices should be considered as hippocampal body using a variety of high-resolution MR images.
Members of the Body Ranging Group include Daniela Jesseca Palombo, Attila Keresztes, Robin de Florès, Joshua Lee, Lorenzo Pasquini, Elliott Johnson, Elizabeth Marie Mulligan, Meg Schlichting, Yushan Huang.
Outer Boundary Group
This working group aims at precisely developing and testing tracing guidelines with respect to the outer boundaries of the hippocampus with surrounding structures and CSF spaces. The current protocol details (and outline structure) were modeled after the recently validated Harmonized Hippocampal Protocol (HarP) for volumetric segmentation of the whole hippocampus, adapting these previously-defined guidelines to the specificities of our high-resolution images.
Members of the Outer Boundary Group include Robert S.C. Amaral, David Berron, Prabesh Kanel, John Pluta, Trevor Steve. We are also in contact with Marina Boccardi and Martina Bocchetta to benefit from their experience with HarP.
Inner Boundary Group
This working group is meant to develop and test geometric heuristic rules to identify boundaries between subfields within the hippocampal body. These rules will notably be based on anatomical landmarks observable in histological samples.
Members of the Outer Boundary Group include David Berron, Valerie Carr, Robin de Flores, Nikolai Malykhin & Rosanna Olsen.