Abstract 15565: A New Non-Invasive Method for the Detection of Local Inflammation Atherosclerotic Lesions: an Experimental Study with Microwave Radiometry
Background: The presence of inflammatory cells is considered a histological hallmark of vulnerable atherosclerotic lesions. Intravascular thermography (IVT) is the only method currently available, which can measure heat production indicating inflammation of vulnerable lesions, . Microwave radiometry (MR) is a new non-invasive diagnostic method that provides accurate measurements of the temperature of internal tissues, which also reflects local inflammation. We studied in an experimental atherosclerotic model whether thermal heterogeneity measured by MR is correlated with the one measured by IVT and with the histologic findings of the aortic samples.
Methods: Microwave radiometry was applied non-invasively in 60 atherosclerotic segments of rabbits aorta (5 segments, 2cm long in 6 rabbits), as well as in 60 control segments. The system measures natural electromagnetic radiation from the internal tissues at microwave frequencies that is proportional to the temperature of tissue. Thereafter, IVT was performed in the same segments. For both techniques temperature difference (ΔT) was assigned as the temperature of each segment minus the minimal temperature of the 5 segments. Aortas were excised and during histologic analysis were divided into 2 types according to the inflammatory cell content and the degree of CD3 and CD68 immunoreactivity.
Results: Microwave radiometry detected that ΔT of atherosclerotic aortas was significantly higher compared to controls (1.02±0.23 vs 0.21±0.09°C,p < 0.001) (n=27) had higher ΔT by MR compared to segments with low (n=69) (1.12±0.16 vs 0.41±0.35°C, p < 0.001) (n=28) had higher ΔT by MR compared to segments with low (n=68) (1.10±0.23°C vs 0.41±0.34°C, p<0.001). ΔT of atherosclerotic segments assessed by both methods correlated with plaque thickness assessed by histology (MR: R=0.60, p < 0.001, IVT:R =0.41, p = 0.004).
Conclusions: Microwave radiometry may detect atherosclerotic plaque inflammation in an animal model of atherosclerosis. Increased thermal heterogeneity detected by MR reflected the presence of high-risk plaque features. This new non-invasive method may provide in vivo atherosclerotic plaque functional assessment, having thus the potential to characterize significant plaque features.
- © 2011 by American Heart Association, Inc.