Demyelinating Diseases — MRI

A 28-year-old woman from Delhi presents with acute onset blurred vision in the left eye and pain on eye movement for 3 days. Fundoscopy reveals a swollen optic disc. MRI brain with contrast shows T2 hyperintense lesion in the left optic nerve with perilesional edema and central enhancement. CSF analysis shows oligoclonal bands. What is the most likely diagnosis?

A 28-year-old woman from Delhi presents with acute onset blurred vision in the left eye and pain on eye movement for 3 days. Examination reveals relative afferent pupillary defect and reduced colour vision. MRI brain with contrast shows a T2-hyperintense lesion in the left optic nerve with central gadolinium enhancement. CSF analysis shows oligoclonal bands. What is the most likely diagnosis and what is the significance of the imaging finding?

A 35-year-old man from Mumbai with a 5-year history of relapsing-remitting neurological symptoms (weakness, sensory loss, diplopia) presents with acute lower limb weakness and urinary retention. MRI spine shows a T2 hyperintense lesion spanning 4 vertebral segments in the thoracic cord with central enhancement. Brain MRI reveals multiple T2/FLAIR hyperintense lesions in the periventricular region and corpus callosum. Serum AQP4 antibodies are negative; oligoclonal bands are absent from CSF. What is the most likely diagnosis?

A 35-year-old man from Bangalore presents with progressive weakness in both legs and numbness over 6 weeks. Examination shows spastic paraparesis with hyperreflexia and extensor plantar responses. MRI spine reveals a T2-hyperintense lesion extending from T2 to T8 vertebral levels, spanning the entire cord width. T1 post-gadolinium imaging shows no enhancement. Brain MRI is normal. What is the most likely diagnosis?

In multiple sclerosis, which MRI finding is considered pathognomonic and represents demyelinating lesions oriented perpendicular to the lateral ventricles?