APPLICATIONS OF MAGNETIC RESONANCE IMAGING - BASED BRAIN VOLUMETRY IN THE DIAGNOSIS AND FOLLOW - UP OF PATIENTS WITH MULTIPLE SCLEROSIS

Abstract

Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system (CNS) characterized by a widely variable clinical manifestation and course. Although MS is generally considered a disease of the white matter (WM), pathology is also found in the gray matter (GM). Axonal loss and neurodegeneration occur early and can lead to permanent neurological and cognitive impairment.
Magnetic Resonance Imaging (MRI) offers excellent anatomical - structural information and since 2001, MRI has been incorporated in the diagnostic workup of patients with a clinical suspicion of MS (1). Changes in brain volume, detected from the early stages of MS and proceeding throughout the course of disease, may offer an accurate measure of neurodegeneration and tissue damage. Qualitative (i.e., visual) interpretation of structural brain images can detect only macroscopic changes and shows a low level of interobserver agreement. On the other hand, advanced MRI techniques –such as MRI-based brain volumetry– developed in the recent years through the advances in computational technology have greater sensitivity than conventional MRI and allow quantitative assessment of structural brain images. Since manual identification and measurement of MS lesions on MRI can be extremely time-consuming and subjective, multiple semi-automated and automated methods for the determination of overall and regional brain volumes and of “lesion load” have been suggested. Nonetheless, although these methods seem sensitive and reproducible, their role should be mainly supportive to that of visual assessment of brain structural images, since variable factors (e.g. pseudoatrophy) can have a confounding influence on measurements.
After a brief overview of the different volumetric MRI techniques, this review will assess the clinical use of MRI-derived brain volumetry in the diagnosis, follow-up and monitoring of treatment effects in patients with MS.