Summary
Carotid atherosclerotic plaques are a major cause of ischaemic stroke. The biomechanical
environment to which the arterial wall and plaque is subjected to plays an important
role in the initiation, progression and rupture of carotid plaques. MRI is frequently
used to characterize the morphology of a carotid plaque, but new developments in MRI
enable more functional assessment of carotid plaques. In this review, MRI based biomechanical
parameters are evaluated on their current status, clinical applicability, and future
developments. Blood flow related biomechanical parameters, including endothelial wall
shear stress and oscillatory shear index, have been shown to be related to plaque
formation. Deriving these parameters directly from MRI flow measurements is feasible
and has great potential for future carotid plaque development prediction. Blood pressure
induced stresses in a plaque may exceed the tissue strength, potentially leading to
plaque rupture. Multi-contrast MRI based stress calculations in combination with tissue
strength assessment based on MRI inflammation imaging may provide a plaque stress-strength
balance that can be used to assess the plaque rupture risk potential. Direct plaque
strain analysis based on dynamic MRI is already able to identify local plaque displacement
during the cardiac cycle. However, clinical evidence linking MRI strain to plaque
vulnerability is still lacking. MRI based biomechanical parameters may lead to improved
assessment of carotid plaque development and rupture risk. However, better MRI systems
and faster sequences are required to improve the spatial and temporal resolution,
as well as increase the image contrast and signal-to-noise ratio.
Keywords
Atherosclerosis - inflammation - MRI - biomechanics