Quantification and clinical relevance of brain atrophy in multiple sclerosis: a review

Abstract

Multiple sclerosis is known to be an inflammatory demyelinating disease characterized mainly by multifocal areas of white matter lesions. Recently, cortical lesions and brain atrophy have emerged as new pathological markers of disease progression. Brain tissue loss can now be easily and reproducibly detected and quantified by MRI, which has led to an increasing amount of research correlating brain tissue loss with other MRI markers, such as white matter lesions, and to clinical disabilities (motor or cognitive), in order to assess its clinical relevance. In this review, we summarize the different MRI-based methods used to quantify whole and regional brain atrophy, and discuss the relevance of brain atrophy in MS through its relationship with characteristic brain lesions, disability and cognition. Lastly, we emphasize the role of brain atrophy in different phenotypes of MS. According to this review of the current literature, the grey matter (GM) atrophy is now well-established in MS and has been found to be strongly associated with clinical and cognitive deterioration. This GM volume loss is characterized by a focal atrophy in the deep grey nuclei but also by diffuse cortical atrophy. Phenotypic variation can be associated with different degrees and regional location of brain atrophy but more investigations are necessary to specify the discrepancies against brain atrophy between the different forms of the disease.

Stress-induced brain activity, brain atrophy, and clinical disability in multiple sclerosis

“…The latter finding is compatible with the observations that the cerebellum receives major NE projections from the locus coeruleus (26) and that the stress hormone NE is closely linked to inflammatory processes (9,10). Thus, given that inflammation is a source of GM atrophy (38), which is pronounced in the cerebellum (29,39), one might conclude that the negative link of stress-induced brain activity and GM atrophy might be mediated by the NE system. Importantly, analysis 4a also showed that stress-induced activity is positively related to GM volume in overlapping cerebellar areas of controls.…”

Automated Determination of Brain Parenchymal Fraction in Multiple Sclerosis

“…1,2 At present, the most commonly used radiologic markers for disease activity and progression are the number of new T2 lesions and gadoliniumenhancing T1 lesions. Brain atrophy is generally afforded a subordinate role in follow-up in clinical practice and is often estimated only by visual inspection.…”

“…Several different techniques based on MR imaging, manual as well as semiautomatic and automatic, can be used to accomplish this. 1,7,8 Manual techniques require postprocessing labor that may limit the feasibility of clinical use and may introduce operator-dependent errors, making automated techniques a preferable alternative. Automated methods generally use image intensity histograms of conventional MR image acquisitions, either to separate tissue types directly by setting intensity thresholds or for comparison with brain templates or a priori tissue maps.…”

Quantification of Volumetric Changes of Brain in Neurodegenerative Diseases Using Magnetic Resonance Imaging and Stereology

“…Moreover, high contrast makes segmentation between the different cerebral compartments easier. Depending on the compartment of interest, tissue contrast can be chosen such as CSF/parenchyma or gray/white matter (Grassiot et al, 2009). There are many different segmentation methods for estimating brain volume using manual or automated techniques.…”