Demyelination protocol (MRI)

MRI protocol for demyelinating diseases is a group of MRI sequences put together to best approach these white matter disorders characterized by the destruction or damage of normally myelinated structures. These disorders may be inflammatory, infective, ischaemic or toxic in origin. 

Generally, the same protocol will be used for the diagnosis and follow-up of multiple sclerosis

Note: This article is intended to outline some general principles of protocol design. The specifics will vary depending on MRI hardware and software, radiologist's and referrer's preference, institutional protocols, patient factors (e.g. allergy) and time constraints. 

Sequences

A good protocol for this purpose involves at least:

  • T1
    • sequence: preferably 1.0-1.5mm 3D isotropic acquisition or if only 2D available then <3mm slice thickness, no skip, with <1mm inplane resolution 4,5
    • purpose: anatomical, best for assessing volume loss. This is particularly important for multiple sclerosis as brain volume loss is correlated with disease severity and disability 2,3
  • T2
    • sequence:  preferably 1.0-1.5mm 3D isotropic acquisition or if only 2D available then <3mm slice thickness, no skip, with <1mm inplane resolution 4,5
    • purpose: white matter signal abnormality. T2 is more sensitive than FLAIR for infratentorial lesions
  • FLAIR
    • sequence:  preferably 1.0-1.5mm 3D isotropic acquisition or if only 2D available then <3mm slice thickness, no skip, with <1mm inplane resolution 4,5
    • purpose: white matter signal abnormality. FLAIR is more sensitive than T2 in detection of juxtacortical and periventricular plaques
  • DWI/ADC
    • purpose: active demyelinating MS plaques may demonstrate restricted diffusion
  • T1 C+ (Gd) 
    • if a diagnosis of multiple sclerosis has not been made, or an alternative diagnosis is being considered in a patient with known multiple sclerosis, giving contrast is helpful either as 1.0-1.5mm 3D isotropic acquisition or if only 2D available sequence 4,5
    • sequence: axial or 3D isotropic acquisition
    • purpose: active demyelinating lesions show enhancement, which is often incomplete around the periphery (open ring sign)
    • Gadolinium based contrast agents (GBCAs) for CNS 1
    • all these GBCAs are approved by FDA at identical administered total doses of 0.1mmol/kg body weight 1
Optional additional sequences
  • SWI or T2*
  • double inversion recovery (DIR)

PML surveillance

In patients who are on natalizumab (TysabriTM), especially if they are positive for John Cunningham virus (JC virus), regular surveillance with MRI for the development of progressive multifocal leukoencephalopathy (PML) is recommended 4. In patients who are JC virus positive, or who have been on >18 months of treatment with natalizumab 3-6monthly scans are recommended but do not require the entire protocol. In these patients, an abbreviated protocol consisting only of FLAIR and DWI suffices 4

 

MRI protocols
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