Abstract 1909: Association between Adventitial Vasa Vasorum and Incident Fibrous Cap Rupture: A Prospective, Longitudinal Dynamic Contrast-Enhanced MRI Study
Background: Intimal neovasculature is thought to arise from adventitial vasa vasorum and may represent a pathway for inflammatory cell infiltration of the plaque, predisposing it to disruption. Using a dynamic contrast-enhanced (DCE) MRI protocol, we have shown a strong correlation between the rate of contrast enhancement of the artery wall, quantified by the transfer constant Ktrans, and histological evidence of neovasculature and macrophage infiltration in carotid plaques. The technique was recently modified to only capture Ktrans values from adventitial tissue. We tested the hypothesis that the extent of adventitial vasa vasorum as measured by Ktrans at baseline is associated the development of new fibrous cap rupture during follow-up.
Methods: 35 subjects with 50–79% carotid stenosis by ultrasound were imaged at baseline and 3 years with high-resolution, multi-contrast DCE-MRI at 1.5T. Two reviewers blinded to time point reached a consensus interpretation for each scan. At each matched axial location, intraplaque hemorrhage (IPH) and fibrous cap status (intact or disrupted) were identified.
Results: Amongst 35 arteries evaluated, 5 arteries were excluded because of poor image quality at either time-point. Baseline mean Ktrans was significantly higher in arteries with fibrous cap rupture and/or IPH at baseline (n=14) compared to those with intact surface without IPH (n=16) (0.13±0.005/min vs. 0.10±0.004/min, respectively; p<0.001). Amongst 23 arteries with an intact fibrous cap on the initial MRI, baseline mean Ktrans was significantly higher in arteries that developed MRI evidence of new fibrous cap rupture at 3yrs (n=4) compared to those with intact surface at follow-up (n=19) (0.14±0.009/min vs. 0.10±0.004/min, respectively; p=0.004). 50% of the arteries with a baseline mean Ktrans > 0.114/min developed fibrous cap rupture during follow-up (area under the curve = 0.91).
Conclusion: Extent of the carotid artery adventitial vasa vasorum, as measured by DCE-MRI, is greater in plaques with evidence of fibrous cap rupture and/or intraplaque hemorrhage. Furthermore, findings from this prospective, longitudinal study demonstrate that baseline adventitial Ktrans has a strong association with the development of future fibrous cap rupture.