From the Guidelines
Typical MS lesions on enhancement are characterized by a short-lived, nodular or ring-like pattern of hyperintensity on T1-weighted MRI sequences after gadolinium administration, typically lasting 2-8 weeks. The enhancement pattern is a key feature in the evaluation of patients suspected of multiple sclerosis, as it indicates active inflammation and disruption of the blood-brain barrier 1. These lesions are often found in periventricular regions, the corpus callosum, juxtacortical areas, infratentorial structures, and the spinal cord. The presence of enhancing lesions alongside non-enhancing lesions demonstrates the characteristic dissemination in time that is crucial for MS diagnosis. Some key features to note about enhancing MS lesions include:
- They are best appreciated on moderately T1-weighted spin-echo or gradient-echo images, but can be more difficult to detect on heavily T1-weighted images 1
- Enhancement should be confirmed by a corresponding abnormality on T2 or T2-FLAIR images to rule out flow artefact or other causes of hyperintensity 1
- Larger lesions can evolve into ring-enhancing lesions, and those that abut the ventricles or cortex can show 'open-ring' enhancement, which can help differentiate them from neoplastic lesions or abscesses 1
- Leptomeningeal enhancement is extremely rare in MS, and if present, should raise suspicion of alternative pathology such as (neuro)sarcoid or granulomatous diseases 1.
From the Research
Typical MS Lesion on Enhancement
- A typical MS lesion on enhancement is characterized by the breakdown of the blood-brain barrier (BBB), which can be detected using gadolinium-enhanced MR imaging 2, 3, 4.
- Gadolinium enhancement patterns can help identify active inflammatory lesions in MS, with the most frequent location of gadolinium-enhanced (Gd+) lesions being subcortical 5.
- The presence and extent of enhancement can be correlated with the evolution of MS, although the sensitivity and specificity of conventional Gd-enhanced MRI may be limited 3.
- The use of triple dose gadolinium may enable better assessment of low-grade MS inflammation, and cell-specific imaging techniques and multiparametric MR imaging studies can increase understanding of the pathologic steps between inflammation and irreversible tissue loss 3.
Gadolinium Enhancement in MS
- Gadolinium-enhanced MR imaging is currently the reference standard to detect active inflammatory lesions in MS 2.
- Gd-enhanced MR imaging can show the time dissemination of lesions and has a high predictive value for subsequent evolution to clinically definite MS 3.
- The number and location of Gd+ lesions can be analyzed to study the clinico-radiological paradox in MS relapse, with most patients showing several Gd+ lesions on brain MRI, even when the clinical manifestation is outside of the brain 5.
- Gd-enhanced MR imaging appears to be more sensitive than high-iodine computed tomography (HICT) in the detection of transient abnormalities of the BBB that occur in patients with active MS 4.