Towards In-Vivo Histology using Magnetic Resonance Imaging (MRI)

Understanding the normal and diseased human brain crucially depends on reliable knowledge of its anatomical microstructure and functional micro-organization (e.g., cortical layers and columns of 200-1000μm dimension). Even small changes in this microstructure can cause debilitating diseases. Until now, the microstructure can only be reliably determined using invasive methods, e.g., ex-vivo histology. This limits neuroscience, clinical research and diagnosis. I will discuss how an interdisciplinary approach developing novel MRI acquisition methods, image processing methods and integrated biophysical models aims to achieve quantitative histological measures of brain tissue, leading to the emerging field of in vivo histology using MRI. In particular, I will present recent methodological advances in quantitative MRI and related biophysical modelling. Examples will include: characterization of cortical myelination and its relation to function; mapping of the axonal g-ratio in a population; changes due to spinal cordinjury; age-related brain changes. The presentation will conclude with an outlook on future developments, applications and the potential impact of in-vivo histology using MRI.