Abstract 15140: Microwave Radiometry for the Detection of Local Inflammatory Activation in Atherosclerotic Plaques: A New Non-Invasive Method.
Background: Intravascular thermography (IVT) is the only method currently available which can be used in vivo to measure heat generation from atherosclerotic plaques. Microwave radiometry (MR) is a new non-invasive method for measuring temperature from internal tissues at microwave frequencies. We investigated in an experimental atheromatic model, whether thermal heterogeneity measured by MR is correlated with IVT and histological findings.
Methods: Twenty four New Zealand rabbits were randomized to either a normal (n=12) or cholesterol-rich diet (n=12) for 6 months. Thereafter, temperature measurements of the abdominal aortas were performed 1) invasively with IVT and 2) noninvasively with MR (RTM-01-RES system). All aortas were divided by optical coherence tomography in 5 segments. For both techniques temperature difference (ΔT) of each segment was assigned as the temperature of each segment minus the minimal temperature of the 5 segments. All animals were euthanized after the procedure and aortas were extracted for histological analysis.
Results: Both MR and IVT detected that ΔT of atherosclerotic aortic segments were significantly higher compared to ΔT of the controls (MR: 1.02±0.23°C vs 0.21±0.09°C, p<0.001, IVT: 0.19±0.03°C vs 0.01±0.01°C, p<0.001). Temperature differences detected by the two methods correlated positively (p<0.001, R=0.57). In atherosclerotic segments, ΔT 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). Segments with increased infiltration of lymphocytes(n=27) had higher ΔTMR compared to segments with low expression (<3) (n=69) (1.12±0.16°C vs 0.41±0.35°C, p<0.001). Segments with increased expression of mast cells(n=28) had higher ΔTMR compared to segments with low expression (<3) (n=68) (1.10±0.23°C vs 0.41±0.34°C, p<0.001).
Conclusions: Microwave radiometry is a new non-invasive method for detection of local inflammatory activation of atherosclerotic plaques. The results of the current study justify the clinical application of this method for the detection of the inflammatory activation in atherosclerotic plaques.
- © 2010 by American Heart Association, Inc.