[LearnMRI] Vascular changes related to Alzheimer's dementia observed through MRI

26 Dec 2023     #bio #brainImaging #mri

When amyloid beta (A$\beta$) deposits, the likelihood of Alzheimer’s dementia increases. Prior to brain damage caused by A$\beta$ deposition, vascular changes are observed, which can be improved through lifestyle changes or medication. Various types of vascular changes that can be observed through various forms of MRI exist.

Choroid plexus (ChP)

• MRI type: T1-weighted image (T1WI)
• ChP: A network of vessels and cells found in the brain’s ventricles.
  • Acts as a gateway for immune cells between the blood and the brian.
  • Produces cerebrospinal fluid (CSF) aiding in clearing waste and toxins from brain cells.
• The volume of ChP correlates with the severity of cognitive impairment.

Perivascular space (PVS)

• MRI type: T2-weighted image (T2WI)
• PVS: Space surrounding arteries penetrating the brain
  • Concept encompassing fluids and tissues within and around vessel walls.
  • A component of the blood-brain barrier (BBB).
• Fluid dynamic
  • Acts as a network between cerebrospinal fluid (CSF) and interstitial fluid (ISF), cleansing byproducts of the brain.
  • Known to play a role in the brain’s lymphatic system → glymphatic system.
• Enlarged perivascular spaces (EPVS) are associated with degenerative brain diseases and various brain disorders.
• The volume of PVS is proportional to the likelihood of amyloid beta (A$\beta$) positivity.
  • Pronounced tendency in the temporal lobe: A$\beta$ positive patients often have abundant temporal PVS.

White matter hyperintensity (WMH)

• MRI type: FLAIR
• WMH: An excessive concentration of white matter
  • Primarily caused by aging, manifested by loss of blood flow and cellular damage.
  • Subcortical hyperintensity: WMH near the basal ganglia.
• While direct association with Alzheimer’s dementia hasn’t been confirmed, observations suggest a proportional relationship between A$\beta$ positivity and WMH volume in patients.