ISMRM 24th Annual Meeting & Exhibition 07-13 May 2016 Singapore

Weekend Educational Course: Validation of Structural Measurements with Diffusion MRI

Skill Level: Intermediate

Organizers: Daniel C. Alexander, Ph.D., Derek K. Jones, Ph.D. & Guoying Liu, Ph.D.

Sunday 08 May 2016

The lack of ground truth on the connectional diagram and tissue microstructure of the human brain is a major impediment to the evaluation and optimization of methods for diffusion MRI (dMRI), which has a high incidence of false negatives and positives due to limited sensitivity. This often leads to skepticism towards this technique. This educational session covers all types of ex vivo and in vivo validations, using animal models and/or in human. Successful validation would help interpret and quantify these measurements as meaningful physiological parameters in normal subjects and patients.

Target Audience
Scientists and clinicians interested in learning what has been done in validation of commonly used MRI diffusion methods (tractography and tissue microstructure) and applying those methods in their own scientific inquiries and the use of these measurements in both basic research and clinical applications.

Educational Objectives
Upon completion of this course, participants should be able to:

  • Have an overview of the state of the art on dMRI validation;
  • Improve the understanding of what can and cannot be measured using dMRI;
  • Learn a host of combined techniques that are useful for validation from numerical, phantom, ex vivo tissue, histological, and in vivo tracer studies; and
  • Learn about methods to improve the fidelity of dMRI‐based methods by incorporating anatomically informed priors (from optical coherence tomography, polarized light imaging, CLARITY) that are based on accurate statistical models of the distribution of trajectories taken by axons and fiber bundles in white matter.

Moderators: Geoffrey Parker, Carlo Pierpaoli
Theoretical Underpinnings of Building a Validation Framework of Diffusion Experiments
Evren Ozarslan1
1Bogazici University
Diffusion magnetic resonance is a powerful probe into tissue microstructure. Theoretical investigations commonly focus on establishing the relationships between simplified environments with the magnetic resonance signal. In this talk, the essential tools and a brief description of the building blocks of a comprehensive model of diffusion taking place in tissue will be discussed. Main mathematical approaches will be reviewed at some depth.

Numerical Phantoms
Gary Zhang1
1Computer Science, University College London
Numerical phantoms have played and will continue to play an important role in the development and validation of advanced diffusion MRI techniques.  They complement biological phantoms (in vitro, ex vivo and in vivo) with their controllability and physical phantoms with their flexibility.  This talk will review the aspects of diffusion MRI techniques that have benefited from validation with numerical phantoms and the range of numerical phantoms currently available.  Examples of using numerical phantoms for validating the mapping of tissue microstructure and structural connectivity in the brain will be presented.

Physical hardware phantoms for the validation of diffusion MRI
Els Fieremans1
1Radiology, New York University School of Medicine
Physical hardware diffusion phantoms with a well-defined structure, composition and architectural organization can serve as a gold standard for the validation of diffusion MRI. In this lecture, we aim to provide guidelines on how to choose or manufacture a synthetic diffusion phantom that addresses the needs of your project, going from setting up a quality assessment diffusion protocol on a clinical scanner, developing and testing a novel diffusion sequence, validating biophysical models to evaluating tractography models. 

Break & Meet the Teachers
Validation of Inferences About Tissue Microstructure
Matthew Budde
Diffusion MRI is unique in its ability to derive microstructural tissue information.  However, since structure is inferred from measurements of diffusion, validating DWI findings with other modalities is important for a complete understanding of diffusion MRI and its relationship to the true underlying tissue microstructure.  This session will provide an overview of methods to validate and quantify the relationship between diffusion MRI findings and the true underlying biology.

Validation of White-Matter Pathways Reconstructed with Diffusion Tractography
Anastasia Yendiki1
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital & Harvard Medical School, Charlestown, MA, United States
This presentation reviews the techniques that can be used to validate WM pathway reconstructions derived from diffusion MRI in humans and non-human primates. The relative merits of the techniques are discussed. The potential for an integrative approach that uses complementary information from chemical tracing in non-human primates, optical imaging in human tissue, as well ex vivo diffusion MRI at microscopic spatial resolutions, is outlined.

Accuracy & Reliability in Population Studies & Clinical Applications
carlo pierpaoli1
Despite the large body of research studies in humans published using Diffusion MRI, and the availability of very sophisticated models for diffusion MRI data analysis, advanced diffusion MRI applications still have not percolated into clinical practice.  In this talk we will review factors affecting accuracy and reliability of Diffusion MRI that have hindered a larger clinical dissemination of this technique and the most promising solutions to this problem.

Panel Discussion & Questions/Comments from the Audience
Adjournment & Meet the Teachers

The International Society for Magnetic Resonance in Medicine is accredited by the Accreditation Council for
Continuing Medical Education to provide continuing medical education for physicians.