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 to 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

Although, as is the case with all MRI protocols, there is no such thing as a universally agreed upon MRI protocol to image an individual with a suspected neurodegenerative condition, what is essential is that good quality three plane imaging (sagittal, coronal and axial) is obtained which includes T1, T2, FLAIR, DWI and T2* (SWI ideally) sequences.

A fairly standard protocol may include:

• T1​
  • sequence:  volumetric gradient-echo e.g. MPRAGE, preferably isometric e.g. 0.9 mm reformatted in three planes
  • purpose: anatomical, best for assessing regional volume loss and may be used for automated brain morphometry
• T2
  • sequence: fast spin echo, whole-brain or limited to basal ganglia and posterior fossa (thins e.g. 3 mm)
  • 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 abnormalities such as small vessel ischemia 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) 
• T2* (e.g. SWI)
  • sequence: SWI including phase and magnitude images
  • purpose: microhemorrhages (e.g. cerebral amyloid angiopathy (CAA), hypertensive encephalopathy). Mineral deposition in the cortex (e.g. Alzheimer disease, amyotrophic lateral sclerosis (ALS)). Loss of low signal in substantia nigra (Parkinson disease)

Optional additional sequences:

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