Imaging Biomarkers and Lesion Dynamics in Multiple Sclerosis

Multiple sclerosis (MS) is characterised by focal white matter lesions arising from immune-mediated demyelination, neuroaxonal injury and gliosis. Modern magnetic resonance imaging (MRI) techniques have evolved beyond mere lesion counting to quantify dynamic lesion behaviour and tissue integrity. Iron-sensitive modalities reveal paramagnetic rims that demarcate chronic active lesions, indicating persistent microglial and macrophage activation at lesion borders. Volumetric longitudinal MRI identifies slowly expanding lesions (SELs) that exhibit gradual growth over months to years, reflecting smouldering inflammation. Quantitative susceptibility mapping (QSM) provides voxel-wise measures of magnetic susceptibility, enabling precise mapping of iron deposition. Myelin water fraction (MWF) imaging quantifies the proportion of water trapped between myelin bilayers, serving as a surrogate for myelin content. The central vein sign (CVS), visible on susceptibility-weighted imaging (SWI), strengthens diagnostic specificity by highlighting perivenular lesion morphology. Together, these biomarkers capture acute inflammatory activity, chronic lesion expansion, remyelination potential and neurodegeneration. By tracking lesion rims, volume changes, myelin loss and iron accumulation, researchers can correlate imaging findings with clinical disability, cognitive performance and therapeutic response. As a global toolset, these techniques promise to refine prognosis, guide treatment selection and monitor emerging remyelinating or anti-inflammatory therapies.

Research from Nature Portfolio

Recent work using QSM has demonstrated that the presence of even a single rim-positive lesion markedly modifies the relationship between overall lesion burden and clinical outcomes in relapsing–remitting MS. Patients harbouring chronic active lesions with hyperintense QSM rims exhibited worse performance on physical disability scales and cognitive tests, independent of total lesion volume. Moreover, younger patients with rim-positive lesions showed accelerated cortical thinning, indicating an early link between iron-laden inflammation and neurodegeneration. These findings underscore rim lesions as a potential target for therapeutic intervention to attenuate progression.

Imaging Biomarkers and Lesion Dynamics in Multiple Sclerosis publication trend

The graph below shows the total number of articles in imaging biomarkers and lesion dynamics in multiple sclerosis across all publications each year (not limited to Nature Index journals).

Technical terms

Paramagnetic rim lesion (PRL): A lesion edge appearing hypointense on iron-sensitive MRI, marking chronic active inflammation.

Slowly expanding lesion (SEL): A lesion exhibiting gradual volume increase over longitudinal MRI, indicating smouldering activity.

Quantitative susceptibility mapping (QSM): An MRI technique that computes tissue magnetic susceptibility, sensitive to iron deposition.

Myelin water fraction (MWF): The proportion of water bound within myelin sheaths, serving as a metric for myelin integrity.

Central vein sign (CVS): A small vein running centrally through an MS lesion, visualised on susceptibility-weighted MRI.

Susceptibility-weighted imaging (SWI): An MRI sequence exploiting local magnetic field inhomogeneities to highlight iron and venous structures.

References

1. Slow expansion of multiple sclerosis iron rim lesions: pathology and 7 T magnetic resonance imaging. Acta Neuropathologica (2016).
2. Disease correlates of rim lesions on quantitative susceptibility mapping in multiple sclerosis. Scientific Reports (2022).
3. Relationship between paramagnetic rim lesions and slowly expanding lesions in multiple sclerosis. Multiple Sclerosis Journal (2022).
4. Value of 3T Susceptibility-Weighted Imaging in the Diagnosis of Multiple Sclerosis. American Journal of Neuroradiology (2020).