# Tractography dissection variability: What happens when 42 groups dissect 14 white matter bundles on the same dataset?

Kurt G. Schilling, François Rheault, Laurent Petit, Colin B. Hansen, Vishwesh Nath, Fang-Cheng Yeh, Gabriel Girard, Muhamed Barakovic, Jonathan Rafael-Patino, Thomas Yu, Elda Fischi-Gomez, Marco Pizzolato, Mario Ocampo-Pineda, Simona Schiavi, Erick J. Canales-Rodríguez, Alessandro Daducci, Cristina Granziera, Giorgio Innocenti, Jean-Philippe Thiran, Laura Mancini, Stephen Wastling, Sirio Cocozza, Maria Petracca, Giuseppe Pontillo, Matteo Mancini, Sjoerd B. Vos, Vejay N. Vakharia, John S. Duncan, Helena Melero, Lidia Manzanedo, Emilio Sanz-Morales, Ángel Peña-Melián, Fernando Calamante, Arnaud Attyé, Ryan P. Cabeen, Laura Korobova, Arthur W. Toga, Anupa Ambili Vijayakumari, Drew Parker, Ragini Verma, Ahmed Radwan, Stefan Sunaert, Louise Emsell, Alberto De Luca, Alexander Leemans, Claude J. Bajada, Hamied Haroon, Hojjatollah Azadbakht, Maxime Chamberland, Sila Genc, Chantal M. W. Tax, Ping-Hong Yeh, Rujirutana Srikanchana, Colin D. McKnight, Joseph Yuan-Mou Yang, Jian Chen, Claire E. Kelly, Chun-Hung Yeh, Jerome Cochereau, Jerome J. Maller, Thomas Welton, Fabien Almairac, Kiran K. Seunarine, Chris A. Clark, Fan Zhang, Nikos Makris, Alexandra Golby, Yogesh Rathi, Lauren J. O’Donnell, Yihao Xia, Dogu Baran Aydogan, Yonggang Shi, Francisco Guerreiro Fernandes, Mathijs Raemaekers, Shaun Warrington, Stijn Michielse, Alonso Ramírez-Manzanares, Luis Concha, Ramón Aranda, Mariano Rivera Meraz, Garikoitz Lerma-Usabiaga, Lucas Roitman, Lucius S. Fekonja, Navona Calarco, Michael Joseph, Hajer Nakua, Aristotle N. Voineskos, Philippe Karan, Gabrielle Grenier, Jon Haitz Legarreta, Nagesh Adluru, Veena A. Nair, Vivek Prabhakaran, Andrew L. Alexander, Koji Kamagata, Yuya Saito, Wataru Uchida, Christina Andica, Masahiro Abe, Roza G. Bayrak, Claudia A. M. Gandini Wheeler-Kingshott, Egidio D’Angelo, Fulvia Palesi, Giovanni Savini, Nicolò Rolandi, Pamela Guevara, Josselin Houenou, Narciso López-López, Jean-François Mangin, Cyril Poupon, Claudio Román, Andrea Vázquez, Chiara Maffei, Mavilde Arantes, José Paulo Andrade, Susana Maria Silva, Vince D. Calhoun, Eduardo Caverzasi, Simone Sacco, Michael Lauricella, Franco Pestilli, Daniel Bullock, Yang Zhan, Edith Brignoni-Perez, Catherine Lebel, Jess E. Reynolds, Igor Nestrasil, René Labounek, Christophe Lenglet, Amy Paulson, Stefania Aulicka, Sarah R. Heilbronner, Katja Heuer, Bramsh Qamar Chandio, Javier Guaje, Wei Tang, Eleftherios Garyfallidis, Rajikha Raja, Adam W. Anderson, Bennett A. Landman, Maxime Descoteaux

NeuroImage · 2021 · Article

https://doi.org/10.1016/j.neuroimage.2021.118502

## Summary

Forty-two teams dissected fourteen bundles from identical tractograms, revealing large differences in what researchers call the same pathway. Variation between dissection protocols exceeded within-protocol and between-person variation, demonstrating the need for clearer anatomical definitions and reproducible segmentation rules.

## Study overview

An open challenge gave 42 independent teams the same processed whole-brain tractograms from six subjects and asked them to identify fourteen white matter fascicles. The resulting 57 segmentation protocols were compared using both volume-based and streamline-based measures. Even with the underlying streamlines held fixed, differences between protocols were larger than within-protocol or between-subject differences. The study identifies nomenclature, anatomical definitions, and dissection constraints as major targets for improving reproducibility. It does not determine which reconstruction is anatomically correct: external validation is still needed. The limited subject sample and use of a shared tractogram also constrain generalization to other acquisitions and complete processing workflows.

## Findings / topics

- Forty-two teams contributed 57 protocols for dissecting fourteen bundles in six subjects.
- Between-protocol variability exceeded within-protocol and between-subject variability despite identical input tractograms.
- Agreement alone could not establish anatomical accuracy; independent validation remained necessary.

## Resources

- [Original work](https://doi.org/10.1016/j.neuroimage.2021.118502)
- [Open full text](https://pmc.ncbi.nlm.nih.gov/articles/PMC8855321/)

Lab page: https://www.microstructure-connectivity-lab.com/publications/tractography-dissection-variability/

This is a research summary, not the full article.