High spatial overlap but diverging age-related trajectories of cortical magnetic resonance imaging markers aiming to represent intracortical myelin and microstructure

ABSTRACT: Statistical effects of cortical metrics derived from standard T1- and T2-weighted magnetic resonance imaging (MRI) images, such as gray–white matter contrast (GWC), boundary sharpness coefficient (BSC), T1-weighted/T2-weighted ratio (T1w/T2w), and cortical thickness (CT), are often interpreted as representing or being influenced by intracortical myelin content with little empirical evidence to justify these interpretations. We first examined spatial correspondence with more biologically specific microstructural measures, and second compared between-marker age-related trends with the underlying hypothesis that different measures primarily driven by similar changes in myelo- and microstructural underpinnings should be highly related. Cortical MRI markers were derived from MRI images of 127 healthy subjects, aged 18–81, using cortical surfaces that were generated with the CIVET 2.1.0 pipeline. Their gross spatial distributions were compared with gene expression-derived cell-type densities, histology-derived cytoarchitecture, and quantitative R1 maps acquired on a subset of participants. We then compared between-marker age-related trends in their shape, direction, and spatial distribution of the linear age effect. The gross anatomical distributions of cortical MRI markers were, in general, more related to myelin and glial cells than neuronal indicators. Comparing MRI markers, our results revealed generally high overlap in spatial distribution (i.e., group means), but mostly divergent age trajectories in the shape, direction, and spatial distribution of the linear age effect. We conclude that the microstructural properties at the source of spatial distributions of MRI cortical markers can be different from microstructural changes that affect these markers in aging

MJM MedTalks (S01E02): A Conversation with Dr. Shirin Enger

Podcast Links: Spotify Anchor   McGill Journal of Medicine (MJM) MedTalks is a Podcast series where members of the McGill Faculty of Medicine and Health Sciences are interviewed on topics related to career, research, advocacy and more. The aim of MedTalks is to open a space where faculty members can share information and advice for trainees in healthcare and medical sciences. In this episode, MSc candidate and MJM Podcast Team member Nadia Blostein interviews Dr. Shirin A. Enger, medical physicist and Associate Professor at the Gerald Bronfman Department of Oncology & Medical Physics Unit. This interview focuses on the interdisciplinary and translational nature of medical physics research, the workflow of radiotherapy, and concludes with a list of open-source initiatives that Dr Enger’s group has participated in, including the McMed Hacks Series on Machine Learning and Medical Imaging. The show notes include a transcript of the podcast, a more detailed content overview, glossary of important terms and resources and references. This episode was recorded and edited by MJM Podcast Team member Nadia Blostein with input from the entire MJM Podcast Team and transcribed by Susan Wang

Café Shapiro Anthology, Selected Poems and Short Stories from the 17th Annual Café Shapiro

http://deepblue.lib.umich.edu/bitstream/2027.42/116068/1/CafeShapiro_2014.pd