Segmentation of brainstem AAN nuclei

Authors: Mark D. Olchanyi, Juan Eugenio Iglesias, Brian L. Edlow

E-mail(s): olchanyi [at] mit.edu, jiglesiasgonzalez [at] mgh.harvard.edu and bedlow [at] mgh.harvard.edu

Rather than directly contacting the author, please post your questions on this module to the FreeSurfer mailing list at freesurfer [at] nmr.mgh.harvard.edu

If you use these tools in your analysis, please cite:

* Histology-guided MRI segmentation of brainstem nuclei critical to consciousness. Mark David Olchanyi, Jean Augustinack, Robin L Haynes, Laura D Lewis, Nicholas Cicero, Jian Li, Christophe Destrieux, Rebecca D Folkerth, Hannah C Kinney, Bruce Fischl, Emery N Brown, Juan Eugenio Iglesias, Brian L Edlow, medRxiv; doi: https://doi.org/10.1101/2024.09.26.24314117

See also: BrainstemSubstructures, ThalamicNuclei, HippocampalSubfieldsAndNucleiOfAmygdala

Contents

1. Motivation and General Description
2. Installation
3. Tool usage
4. Frequently asked questions (FAQ)

1. Motivation and General Description

The AANsegment tool generates automated segmentations of ten brainstem nuclei that are part of the ascending arousal network in MRI scans. The nuclei which we segment are listed below:

• ventral tegmental area (VTA)
• locus coeruleus (LC)
• dorsal raphe (DR)
• median raphe (MnR)
• pontis oralis (PnO)
• laterodorsal tegmental nucleus (LDTg)
• parabrachial complex (PBC)
• periaqueductal grey (PAG)
• midbrain reticular formation (mRt)
• pedunculotegmental nucleus (PTg)

We generate segmentations with a Bayesian approach that uses a probabilistic atlas generated from five ex vivo brain specimens manually annotated with corresponding histopathological and immunohistochemical sections. Segmentations from various MRI sequences are illustrated below:

2. Installation

This method requires the use of MATLAB 8.4 (2014b) runtime, which is completely free and does not require a MATLAB license. It can be downloaded from https://ssd.mathworks.com/supportfiles/downloads/R2014b/deployment_files/R2014b/installers/glnxa64/MCR_R2014b_glnxa64_installer.zip. Further instructions to how to install MATLAB runtime can be found here: https://surfer.nmr.mgh.harvard.edu/fswiki/MatlabRuntime

3. Tool Usage

We are in the process of integrating the method into a python framework, but as of current, you can run the method by calling the segmentation shell script:

SegmentAAN.sh <SUBJECT_ID> <SUBJECT_DIR> 

where <SUBJECT_ID> is the FreeSurfer subject folder name and <SUBJECT_DIR> is the directory where the subject folder is stored. <SUBJECT_DIR> is only necessary if it has not been set as an environment variable, or if you want to override it. For standard usage, the method requires a T1 volume and corresponding ASEG volume generated from the FreeSurfer recon-all stream, which is ran with the following command:

recon-all -all -s <SUBJECT_ID>