Understanding Brain atrophy part2(Neuroscience)

1.The role of MR volumetry in brain atrophy assessment in multiple sclerosis: A review of the literature(Pubmed)

Author : Ewelina Marciniewicz 1, Przemysław Podgórski 1, Marek Sąsiadek 1, Joanna Bladowska 1

Abstract : We review the current role of magnetic resonance (MR) volumetry as a meaningful indicator of neurodegeneration and clinical disease progression in multiple sclerosis (MS) patients. Based on a review of the current literature we summarize the mechanisms that contribute to brain atrophy. We present the newest magnetic resonance imaging (MRI)-based methods used in atrophy quantification. We also analyze important biological factors which can influence the accuracy of brain atrophy evaluation. Evidence shows that measures of brain volume (BV) have the potential to be an important determinant of disease progression to a greater extent than conventional lesion assessment. Finally, scientific reports concerning limitations of MRI-based volumetry that affect its implementation into routine clinical practice are also reviewed. The technical challenges that need to be overcome include creating a standardized protocol for image acquisition — a fully automated, accurate and reproducible method that allows comparison in either single-center or multicenter settings. In the near future, quantitative MR research will probably be the basic method used in neurology to monitor the rate of atrophic processes and clinical deterioration in MS patients, and to evaluate the results of treatment.

2.Measurement of whole-brain atrophy in multiple sclerosis (Pubmed)

Author : Daniel Pelletier 1, Kathleen Garrison, Roland Henry

Abstract : Brain atrophy reflects the net result of irreversible and destructive pathological processes in multiple sclerosis (MS). The gross morphological changes can be accurately quantified using standard magnetic resonance imaging (MRI) acquisitions and various image analysis tools. The current methods used to assess whole-brain atrophy in patients with MS can be classified into 2 groups based on their reliance on segmentation and registration. Segmentation-based methods employed to measure whole-brain atrophy in MS include the brain parenchymal fraction, the index of brain atrophy, the whole-brain ratio, the brain to intracranial capacity ratio, fuzzy connectedness/Udupa’s method, 3DVIEWNIX, the Alfano method, and SIENAX. Current registration-based methods used to measure whole-brain atrophy in MS include the brain boundary shift integral, SIENA, statistical parametric mapping, template-driven seg mentation, and voxel-based morphometry. Most of the methods presented here are sensitive to subtle changes in brain structures and have been successfully applied to MS as measures of whole-brain atrophy. Yet comparative studies of these methods are limited and are complicated by the lack of a gold standard for image acquisition, a segmentation algorithm, an image analysis method, or a reproducibility measure. Overall, the measure of whole-brain atrophy from MRI contributes to an appreciation of the dynamics of MS pathology and its relationship to the clinical course of MS. Determination of the relative reproducibility, precision, sensitivity, and validity of these methods will promote the use of whole-brain atrophy measures as components of comprehensive MRI-based outcome assessment in MS clinical trial.