Neurodegenerative protocol (MRI)

MRI protocol for neurodegenerative diseases assessment is a group of MRI sequences put together to best approach a wide variety of disorders, typically slowly progressive, with variable gradual neurologic dysfunction. 

Please, refer on neurodegenerative MRI brain (an approach) for a broad discussion on how to go through these exams.

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

What is essential is that good quality three plane imaging (sagittal, coronal and axial is obtained, preferably with the coronal images angled at right angles to the hippocampus) with T1, T2, FLAIR, DWI and T2* sequences. A fairly standard protocol may include: 

• T1

  • sequence: volumetric gradient echo e.g. MPRAGE, preferably isometric e.g. 0.9mm reformatted in three planes
  • purpose: anatomical, best for assessing regional volume loss
• T2
  • sequence: fast spin echo, whole brain or limited to basal ganglia and posterior fossa (thins e.g. 3mm)
  • purpose: signal intensity of basal ganglia, and posterior fossa structures (often less well seen on FLAIR due to flow artefact)
• FLAIR
  • sequence: whole brain axial or volumetric
  • purpose: white matter signal abnormality such as small vessel ischaemia resulting in multi-infarct dementia and abnormal sulcal signal in leptomeningeal processes (e.g. leptomeningeal carcinomatosis)
• DWI / ADC (or isometric images from optional DTI acquisition)
  • purpose: cortical or deep grey matter restricted diffusion in Creutzfeldt Jakob disease (CJD) and restriction in demyelination of infarction (e.g. cerebral vasculitis) 
• SWI
  • sequence: SWI including phase and magnitude images
  • purpose: microhaemorrhages (e.g. cerebral amyloid angiopathy (CAA), hypertensive encephalopathy). Mineral deposition in cortex (e.g.Alzheimer's disease, amyotrophic lateral sclerosis (ALS)). Loss of low signal in substantia nigra (Parkinson disease)

Optional additional sequences:

• DTI: for tractography
• MR Perfusion: arterial spin labelling or preferably contrast perfusion
• MR spectroscopy