Restricted diffusion preceding gadolinium enhancement in large or tumefactive demyelinating lesions

Area of Science:

• Neurology
• Radiology
• Neuroimaging

Background:

• Restricted diffusion without contrast enhancement typically suggests cerebral ischemia.
• Large or tumefactive multiple sclerosis (MS) lesions can present with this imaging pattern initially.
• Understanding this presentation is crucial for accurate diagnosis and management.

Purpose of the Study:

• To review the clinical and MRI characteristics of patients with MS exhibiting restricted diffusion without initial contrast enhancement.
• To differentiate MS lesions from ischemic events based on imaging patterns and evolution.
• To elucidate the early imaging findings of demyelination in MS.

Main Methods:

• Case review of 3 patients with MS presenting with specific MRI findings.
• Analysis of lesion size, location, diffusion characteristics, and contrast enhancement patterns.
• Correlation of MRI findings with clinical symptoms, CSF analysis, and follow-up imaging.

Main Results:

• All patients had large ( >1 cm) brain MRI lesions associated with new neurologic symptoms.
• Lesions demonstrated prominent restricted diffusion but no initial gadolinium enhancement.
• Follow-up MRI (2-4 weeks) revealed decreased restricted diffusion and patchy gadolinium enhancement, which later resolved.

Conclusions:

• The initial MRI pattern of restricted diffusion without enhancement in large tumefactive MS lesions can mimic cerebral ischemia.
• This imaging evolution suggests early demyelination preceding blood-brain barrier disruption.
• Distinguishing these MS lesions from ischemia is possible through serial imaging and clinical correlation.