Examination of the role of magnetic resonance imaging in multiple sclerosis: A problem-orientated approach

Abstract

Magnetic Resonance Imaging (MRI) has brought in several benefits to the study of Multiple Sclerosis (MS). It provides accurate measurement of disease activity, facilitates precise diagnosis, and aid in the assessment of newer therapies. The imaging guidelines for MS are broadly divided in to approaches for imaging patients with suspected MS or clinically isolated syndromes (CIS) or for monitoring patients with established MS. In this review, the technical aspects of MR imaging for MS are briefly discussed. The imaging process need to capture the twin aspects of acute MS viz. the autoimmune acute inflammatory process and the neurodegenerative process. Gadolinium enhanced MRI can identify acute inflammatory lesions precisely. The commonly applied MRI marker of disease progression is brain atrophy. Whole brain magnetization Transfer Ratio (MTR) and Magnetic Resonance Spectroscopy (MRS) are two other techniques use to monitor disease progression. A variety of imaging techniques such as Double Inversion Recovery (DIR), Spoiled Gradient Recalled (SPGR) acquisition, and Fluid Attenuated Inversion Recovery (FLAIR) have been utilized to study the cortical changes in MS. MRI is now extensively used in the Phase I, II and III clinical trials of new therapies. As the technical aspects of MRI advance rapidly, and higher field strengths become available, it is hoped that the impact of MRI on our understanding of MS will be even more profound in the next decade.

Keywords: Magnetic resonance imaging; multiple sclerosis; problem-oriented clinical approach.

Figure 1

Pathological specimen from a patient who died from an acute worsening of MS. A contrast enhanced MRI done one week prior to death showed enhancing lesions. Histological specimens from corresponding area of the brain showing acute demyelination (Fig 1A) and inflammatory changes (Fig 1B).

Figure 2

Time course of MTR changes in two enhancing lesions using serial, registered images. Differences in MTR changes and recovery noted.[31]

Figure 3

Differences in MTR values between type 1 and type 2 lesions using tissue specific imaging[66]

Figure 4

Correlation between expansion of CD56bright NK cells and inhibition of brain inflammatory activity during treatment with daclizumab[58]

Figure 5

Difficulties in using MRI to monitor treatment response in individual patients