[Brainmap]: Julien Cohen-Adad PhD-In vivo histology with MRI
Abstract:
Recent advances in MRI have led to the development of techniques that provide quantitative measures of tissue microstructure. Axon diameter and density can be inferred from q-space diffusion protocols, while myelin density can be inferred from quantitative magnetization transfer (qMT), myelin water fraction or macromolecular tissue volume (MTV). Surprisingly, these techniques have mostly been studied independently despite their complementarity: together they can provide comprehensive characterization of the fibre microstructure, including quantifying the myelin thickness or the so-called g-ratio. Moreover, most validation work has been done using tissue staining approaches (e.g., luxol fast blue), without looking at the axon microstructure itself. In this talk we will briefly describe some of the techniques for in vivo histology with MRI, how to circumvent acquisition challenges related to susceptibility artifacts in the spinal cord (e.g., high order real time shimming), how to process those data using template-based analysis (https://github.com/neuropoly/spinalcordtoolbox), and finally how to validate those techniques using electron microscopy and automatic segmentation of axon/myelin using deep learning (https://github.com/neuropoly/axondeepseg).
About the Speaker
Dr. Cohen-Adad completed his PhD in 2008 at the University of Montreal and pursued with a 3-year postdoctoral fellowship at the MGH Martinos Center at Harvard University. He is now assistant professor at Polytechnique Montreal, director of the Neuroimaging Research Laboratory at Polytechnique (NeuroPoly) and associate director of the Neuroimaging Functional Unit at University of Montreal. Dr. Cohen-Adad has a background in MR physics and software development. His research focuses on the development of multi-parametric MRI techniques for quantifying microstructure in the brain and spinal cord. These developments include MRI coils, acquisition at ultra-high field (7 tesla), quantitative techniques (diffusion imaging, magnetization transfer, functional MRI) and image processing software (multimodal registration, segmentation, motion correction). His lab has created the Spinal Cord Toolbox, which is the first comprehensive image processing software dedicated to the spinal cord (2000+ downloads). In collaboration with several international hospitals, he has been translating these advanced MRI techniques for studying patients with spinal cord injury and multiple sclerosis. He has published over 85 articles, edited the first book on quantitative MRI of the spinal cord (Elsevier)and has organized several workshops at international conferences (OHBM, ISMRM).
