Progress update from the hippocampal subfields group

Heterogeneity of segmentation protocols for medial temporal lobe regions and hippocampal subfields on in vivo magnetic resonance imaging hinders the ability to integrate findings across studies. We aim to develop a harmonized protocol based on expert consensus and histological evidence. Our international working group, funded by the EU Joint Programme–Neurodegenerative Disease Research (JPND), is working toward the production of a reliable, validated, harmonized protocol for segmentation of medial temporal lobe regions. The working group uses a novel postmortem data set and online consensus procedures to ensure validity and facilitate adoption. This progress report describes the initial results and milestones that we have achieved to date, including the development of a draft protocol and results from the initial reliability tests and consensus procedures. A harmonized protocol will enable the standardization of segmentation methods across laboratories interested in medial temporal lobe research worldwide. •Harmonization of MRI-based segmentation of medial temporal regions is needed.•The Hippocampal Subfield Group includes >200 imaging and anatomy experts worldwide.•Reliable and valid protocol based on specialized histology data set in development.•A modified Delphi procedure is used to determine consensus on protocol rules.•Final protocol will provide subfield delineation in hippocampal body, head, and tail.