Abstract 5545: An Experimental Study With Microwave Thermography for the Assessment of Atherosclerotic Vascular Disease
Background: Intravascular thermography (IVT) is the only method currently available, which can measure heat generation from atheromatic plaques indicating local inflammation. Thermal heterogeneity of the atheromatic plaque has been correlated with mophological characteristics of the culprit lesion in patients with coronary artery disease. Microwave radiometry (MR) is a new non-invasive method. We investigated whether thermal heterogeneity measured by MR is correlated with IVT findings in an experimental model of atherosclerotic disease.
Methods: Microwave radiometry (RTM-01-RES system) was applied noninvasively in 18 atherosclerotic segments of the aorta (3 segments, 5cm long in 6 rabbits) that were clearly separated from each other, as well as in 18 control segments. Microwave radiometry measures natural electromagnetic radiation from the internal tissues at microwave frequencies that is proportional to the temperature of tissue. The system consists of an internal temperature sensor with the antenna, a skin temperature sensor and the data processing unit. The accuracy of measuring the internal temperature of the device is±0.2°C and the depth of temperature detection is 1–7 cm. Thereafter, IVT was performed in the same segments. For both techniques temperature difference (ΔT) was calculated by subtracting the mean temperature of proximal healthy vessel wall from the maximal temperature of each segment.
Results: Thermal heterogeneity was detected by both methods in the rabbits with the high atherogenic diet. Microwave radiometry detected that ΔT of the atherosclerotic aortas was significantly higher compared to the ΔT of the controls (0.98±0.27 °C versus 0.40±0.14°C, p<0.001). These findings were confirmed by the measurements acquired by IVT. Mean temperature difference was 0.07±0.01 °C for the atherosclerotic aortas versus 0.02±0.01°C, (p<0.001) for the control group. The segments that had the highest ΔT were those that were recognized in angiography as having significant atheromatosis.
Conclusion: Microwave radiometry is the first non-invasive method for detection of local inflammatory activation in arterial segments in an experimental model. Further studies in humans should be performed for the evaluation of this method.