Imaging of the vulnerable carotid plaque: role of imaging techniques and a research agenda

Objectives: Atherothrombosis in the carotid arteries is a main cause of
ischemic stroke, and may depend on plaque propensity to complicate with
rupture or erosion, in turn related to qualitative features amenable to in
vivo imaging. This would provide an opportunity for risk stratification
and – potentially – local treatment of more “vulnerable” plaques. We here
review current information on this topic. Methods: We systematically
reviewed the literature for concepts derived from pathophysiological,
histopathological and clinical studies on imaging techniques attempting at
identifying vulnerable carotid lesions. Results: Magnetic resonance
imaging, computed tomography, ultrasound- and nuclear medicine-based
techniques, alone or with multimodality approaches, all have a link to
pathophysiology, and describe different – potentially complementary –
aspects of lesions prone to complication. There is also, however, a true
paucity of head-to-head comparisons of such techniques for practical
implementation of a thorough and cost-effective diagnostic strategy.
Especially in asymptomatic patients, major international societies leave
wide margins of indecision in the advice to techniques guiding
interventions to prevent atherothrombotic stroke. Conclusions: To improve
practical management of such patients – in addition to patient’s
vulnerability for systemic reasons – a more precise identification of the
vulnerable plaque is needed. A better definition of the diagnostic yield
of each imaging approach in comparison with the others should be pursued
for a cost-effective translation of the single techniques. Practical
translation to guide future clinical practice should be based on improved
knowledge of the specific pathophysiologic correlates and on a comparative
modality approach, linked to subsequent stroke outcomes.