Displaying One Session

Teaching Course Fri, Sep 11, 2020
Session Type
Teaching Course
Date
Fri, Sep 11, 2020
Invited Presentations Invited Abstracts

TC01.01 - Technical aspects of 7T imaging as it pertains to MS (at a level geared to neurologists) (ID 1993)

Speakers
Authors
Presentation Number
TC01.01
Presentation Topic
Invited Presentations

Abstract

Abstract

The main objective of this course is to familiarize MS clinicians with the technical basics of 7T MRI. I will first present the benefits of imaging the central nervous system at 7T and introduce some safety considerations for scanning a clinical population at this ultra-high field strength. I will then review examples of 7T brain images acquired on MS patients using state-of-the-art sequences and discuss some of the current technical limitations. Finally, I will mention promising technical developments aimed at overcoming these issues and facilitating the integration of 7T imaging in the clinical workflow.

Collapse
Invited Presentations Invited Abstracts

TC01.02 - 7T MRI - pathology correlation/validation studies (ID 589)

Speakers
Authors
Presentation Number
TC01.02
Presentation Topic
Invited Presentations

Abstract

Abstract

Over the past 15 years the use of ultra-high field magnetic resonance imaging (MRI) at 7.0 Tesla (7T) has increased. These technological advances have offered new opportunities to uncover previously undetectable tissue injury in patients with multiple sclerosis (MS). Combined MRI-histopathologic studies confirmed the expected superior sensitivity and specificity to pathology of 7T-MRI compared to imaging at lower field strengths. Undesirably, though, those studies have also shown the limits of the technology.

Correlative investigations that focused on the detection and pathological characterization of cortical lesions (CLs) have provided an elegant demonstration of the advantage associated to 7T-MRI increased resolution. Specifically, post-mortem studies at 7T confirmed (1) the ability of higher resolution scans to disclose a larger CL burden; and (2) the notion that lesion size sets the limit for their visibility. However, those studies also demonstrated that much of the extensive MS-induced cortical pathology is invisible to ultra-high resolution 7T-MRI, indicating the limitation of currently available mechanisms of contrast in detecting cortical disease.

The insufficient sensitivity of T2-weighted scans at 7T has also been shown when assessing lesions with different degrees of myelin integrity. For example, areas of remyelination are known to contain a lower amount of (thinner) myelin. These areas are not visible using non quantitative MRI techniques, irrespective of the changes in contrast-to-noise ratio associated with 7T scans.

Validation studies exploiting the uniquely superb susceptibility-based contrast at 7T, have led to the discovery of a specific subset of chronic lesions. Such lesions are featured by a core of demyelination surrounded by a complete (or partial) rim of iron, to which susceptibility-based sequences at 7T are exclusively sensitive. Immunohistopathologic analyses demonstrated that this iron is located inside the perilesional microglia responsible for their slow expansion. Studies have also proven that tracking iron using MRI may lead to the identification of pathologies unrelated to activated microglia as well as to as healthy oligodendrocytes.

Cumulatively, pathology correlation and validation studies consolidate the notion that 7T MRI has the potential to better detect and more accurately characterize tissue injury than MRI at lower field strengths. Nevertheless, the discovery of new mechanisms of contrast remains critical so that quantitative and qualitative MRI methods at ultra-high resolution will continue to advance our insights in the yet concealed MS disease.

Collapse
Invited Presentations Invited Abstracts

TC01.03 - Clinical Applications of 7T MRI in MS (ID 1995)

Speakers
Authors
Presentation Number
TC01.03
Presentation Topic
Invited Presentations

Abstract

Abstract

Magnetic resonance imaging (MRI) is the main diagnostic and prognostic tool used in the study and treatment of patients with multiple sclerosis (MS). Visualization of MS pathology by MRI has brought about substantial advances in MS care, including earlier and more accurate diagnoses and the ability to monitor the effects of treatment and visualize subclinical disease activity. Despite these advances, it is well known that standard, clinical MRI fails to visualize much of MS-related pathology. Although current MRI performs well as a tool to measure white matter (WM) inflammation in MS, its ability to quantify gray matter (GM) pathology, meningeal inflammation, neurodegeneration, chronic inflammatory changes, and myelin tissue content is limited. For this reason, researchers continue to strive towards development of new imaging technologies –hoping to bring us closer to in vivo quantification of MS changes analogous to post-mortem histopathology. One such technology is ultra-high field, 7 Tesla (7T) MRI. 7T MRI has been applied to MS and has demonstrated superiority in visualization of WM lesions and GM lesions. Further, 7T MRI has led to the identification of novel biomarkers, such as the central vein sign (CVS), WM lesions with paramagnetic rims, and leptomeningeal inflammation (LME), among others.

In this talk, we will review the data available on application of these techniques in vivo, and review clinical correlations and clinical outcome prediction. Further, with the approval of 7T MRI as a medical device by the FDA in recent years, we will review the potential applications of 7T scanners in clinical settings and for clinical trials.

Collapse