Background: Plaque rupture mechanisms are complex processes, which are dependent on plaque morphology and composition and mechanical characteristics. We have previously demonstrated that the higher risk of plaque complication reported in patients with diabetes and hypercholesterolemia may be due to a specific pattern of strain gradient between plaque and adjacent common carotid artery (CCA) (inward bending stress). In addition, previous studies have suggested that plaque echogenicity is related to the histological components of carotid plaques and that carotid plaque echolucency (low echogenicity) is associated with the development of neurological events.

Objective: of our study was to determine the difference in plaque composition according to the presence of an outward or an inward bending stress (ArtLab system) using an in vivo noninvasive approach with a software for videodensitometry analysis, the MIP system (Medical Image Processing, CNR Pisa), which yields the gray levels distribution of a region of interest (ROI).

Patients: The study included 24 patients with a recent cerebrovascular ischemic event and either a plaque on the far wall of CCA. We divided the patients into two groups according to strain behaviour: pattern A (larger strain at the level of plaque than at the level of CCA, outward bending strain), pattern B (plaque strain smaller than CCA strain, inward bending strain). In all patients digital images of plaques were analyzed offline with MIP.

Results: In 16 patients a pattern A and in 8 patients a pattern B strain behaviour were observed. Demographic and hemodynamic characteristics were similar in the two groups. The prevalence of hypercholesterolemia and diabetes were significantly higher in patients with a pattern B strain behaviour (respectively, 100% vs 56.3% p=0.03 and 62.5% vs 12.5%, p =0.04). Mean gray levels were significantly lower in patients with an inward bending strain compared to patients with an outward bending strain (65±20 vs 95±30, p=0.018).

Conclusions: These results suggest that the higher risk of plaque complication, reported in patients with diabetes and hypercholesterolemia, may be due to a specific pattern of strain gradient between plaque and adjacent CCA and to a different plaque composition.