Current and future role of MRI in the diagnosis and prognosis of multiple sclerosis

Abstract

In the majority of cases, multiple sclerosis (MS) is characterized by reversible episodes of neurological dysfunction, often followed by irreversible clinical disability. Accurate diagnostic criteria and prognostic markers are critical to enable early diagnosis and correctly identify patients with MS at increased risk of disease progression. The 2017 McDonald diagnostic criteria, which include magnetic resonance imaging (MRI) as a fundamental paraclinical tool, show high sensitivity and accuracy for the diagnosis of MS allowing early diagnosis and treatment. However, their inappropriate application, especially in the context of atypical clinical presentations, may increase the risk of misdiagnosis. To further improve the diagnostic process, novel imaging markers are emerging, but rigorous validation and standardization is still needed before they can be incorporated into clinical practice. This Series article discusses the current role of MRI in the diagnosis and prognosis of MS, while examining promising MRI markers, which could serve as reliable predictors of subsequent disease progression, helping to optimize the management of individual patients with MS. We also explore the potential of new technologies, such as artificial intelligence and automated quantification tools, to support clinicians in the management of patients. Yet, to ensure consistency and improvement in the use of MRI in MS diagnosis and patient follow-up, it is essential that standardized brain and spinal cord MRI protocols are applied, and that interpretation of results is performed by qualified (neuro)radiologists in all countries.

Keywords: Diagnosis; Magnetic resonance imaging; Multiple sclerosis.

Fig. 1

2017 McDonald criteria for demonstration of DIS and DIT in patients with a CIS suggestive of MS. Typical MRI examples (orange arrowheads) of (a) periventricular, (b) cortical/juxtacortical, (c) infratentorial and (d) spinal cord MS lesions. DIS can be demonstrated by ≥1 T₂-hyperintense lesions in ≥2 of 4 typical areas of the central nervous system (i.e., periventricular, cortical/juxtacortical, infratentorial or spinal cord). DIT can be demonstrated by (e) a simultaneous presence of Gd-enhancing (orange arrowhead) and non-enhancing (white arrowheads) lesions at any time; (f) a new T₂-hyperintense and/or Gd-enhancing lesion on follow-up MRI (orange arrowheads), with reference to a baseline scan, irrespective of the timing of the baseline MRI. For the definition of both DIS and DIT, the distinction between symptomatic and asymptomatic lesions has been removed in the 2017 revision of the McDonald criteria. (g) In patients with a typical CIS suggestive of MS fulfilling DIS criteria and with no better explanation for the clinical presentation, the demonstration of CSF-specific OCBs, i.e., not present in the serum but only in the CSF, substitutes for the requirement of fulfilling DIT, thus allowing a diagnosis of MS, even if the clinical and MRI findings do not meet the criteria for DIT. Abbreviations: CIS, clinically isolated syndrome; CSF, cerebrospinal fluid; DIS, dissemination in space; DIT, dissemination in time; Gd, gadolinium; MRI, magnetic resonance imaging; MS, multiple sclerosis.

Fig. 2

Examples of cortical lesions, the central vein sign and chronic active lesions. (a) Several cortical lesions are visible in a multiple sclerosis patient on double inversion recovery sequence at 3.0 T. (b) A white matter lesion showing the central vein sign (orange dotted rectangle) on post-contrast T₂-FLAIR∗ sequence at 3.0 T. (c) Among the T₂-hyperintense white matter lesion visible on T₂-FLAIR, one lesion shows an hypointense rim on phase image and SWI sequence at 3.0 T (orange arrow). Abbreviations: FLAIR, fluid-attenuated inversion recovery; SWI, susceptibility-weighted imaging.

Fig. 3

Example of lesions of the optic nerve in multiple sclerosis. (a) On coronal fat-suppressed T₂-weighted sequence, the posterior endo-orbital portion of the right optic nerve is enlarged and shows a hyperintensity (orange arrows), with (b) a focal gadolinium enhancement (orange arrowhead) on post-contrast T₁-weighted sequence.

Fig. 4

Summary of early MRI predictors of subsequent worse disease disability progression and evolution to secondary progressive multiple sclerosis at disease onset. (a) The number and volume of brain T₂-hyperintense white matter lesions; (b) ≥1 infratentorial lesion (orange arrowheads); (c) ≥1 spinal cord lesion at baseline (orange arrowheads); (d) ≥1 gadolinium-enhancing lesions at baseline (orange arrowheads); (e) increase of T₂-hyperintense brain white matter lesion number and volume (especially of deep white matter) during the first 1–5 years; (f) ≥1 infratentorial T₂-hyperintense white matter lesions within 1–3 years (orange arrowheads); (g) ≥1 cortical lesion at baseline (orange arrowheads) on double inversion recovery sequence. Further promising early MRI markers are h) the presence of lesions with the “central vein sign” on susceptibility-based MRI (orange arrowheads); (i) the presence of paramagnetic rim lesions on susceptibility-based MRI (orange arrowheads) (j) presence of substantial brain volume loss at disease onset and/or (k) a faster rate of brain atrophy in the first years of the disease.