Mattias Vågberg

The importance of brain atrophy in neurodegenerative disorders is well-known. Considering the example of multiple sclerosis (MS), brain atrophy has been shown to be a valuable biomarker both for prognostic considerations and for measuring treatment effect. Although determination of brain atrophy is widely used in research regarding MS, it has not yet found its way into the clinical care of individual patients. A large obstacle has been the lack of an available method capable of performing good enough measurements while still conforming to the time restrictions present in the clinical workflow. With this in mind, the method used for brain atrophy measurement in the setting of this study (SyMap) is interesting because it operates with quick enough scanning and postprocessing time to be feasible for clinical use.

The current study used the SyMap method to investigate the brain parenchymal fraction (BPF, often used in atrophy measurements and defined as the ratio between the brain parenchymal volume and total intracranial volume) in individuals with MS and controls. The BPF values found with SyMap were congruent with earlier values reported in the literature. The SyMap method was also found to correlate highly with a reference method (r=0.96, P<.001). The coefficient of variation of repeated BPF measurements was found to be 0.45%. We conclude that the SyMap method is an interesting alternative for clinical brain atrophy measurement in patients with MS.

The question of choosing the correct treatment for an individual patient with MS has become more complex due to new treatment options having recently become available, and even more alternatives are expected to reach clinical MS care in the coming years. This intensifies the need for comprehensive MS disease activity monitoring and more individualized determination of prognosis to use as a basis for treatment decisions. We believe that measuring brain atrophy as a supplementary clinical biomarker adds valuable information to this decision-making process, and we have locally incorporated atrophy measurement into the routine clinical follow-up of patients with MS.

We have also recently used the described method to establish age-stratified normal values for BPF, as is needed to properly evaluate individual clinical BPF values. We hope to publish these results in the near future and also to be able to present them at the coming ACTRIMS-ECTRIMS meeting in Boston in September 2014.

We are, furthermore, currently expanding the research into incorporating an algorithm for automatic identification and volume calculation of MS inflammatory lesions. Several methods for lesion segmentation exist, and lesion volume is frequently used as an endpoint in MS treatment studies. It has been shown to be associated with both clinical disability and disability progression. However, the use of absolute tissue volume of lesions as a biomarker has not yet found its way into the clinical routine, due in large part to the same obstacles that have hindered clinical determination of brain atrophy. We hope that a SyMap-based algorithm can provide another step towards bridging this gap between research and clinical care giving.

Read this article at AJNR.org . . .