Abstract 15779: Increased Thermal Heterogeneity in Carotid Arteries as a Surrogate Marker for Coronary Artery Disease: First Clinical Application of Microwave Radiometry
Background: Intima-media thickness (IMT) of carotid arteries is a well established method for the prediction of cardiovascular events. However, age-related thickening not involving atherosclerosis and inflammation, can affect the specificity of this method. Microwave radiometry (MR) is a new non-invasive method that allows in vivo measuring of the internal temperature of tissues which reflects inflammation. We evaluated the predictive value of thermal heterogeneity measured by MR for the diagnosis of significant CAD.
Method: Forty-two consecutive patients hospitalized for chest pain and scheduled for coronary angiography were evaluated by 1) ultra-sound echo-color Doppler study (US-ECD)of both carotid arteries, and 2) temperature measurements with MR. The following parameters were analyzed: type of plaque (fatty, mixed and calcified), plaque morphology (regular, irregular, ulcerated), homogeneity (heterogeneous, homogenous) and echogenicity (type I-V). Thermal heterogeneity (ΔT) was assigned as the maximal temperature along the carotid artery minus the minimum temperature. Thereafter, MR findings and US measurements were associated.
Results: Significant CAD was found in 30 patients (71.4%) on coronary angiography (CAD group). Mean IMT was higher in carotid arteries of the CAD group (1,29±0,37 vs 0,56±0,18°C, p<0.001). Carotid arteries of the CAD group had also higher ΔT (1,31±0,55 vs 0,53±0,20°C, p<0.001). Among carotid arteries with atherosclerosis (IMT over 0.75mm), fatty plaques had higher ΔT compared to mixed and calcified ones (1.77±0.54 vs 1.08±0.17 vs 0.88±0.15°C accordingly, p<0.05). Ulcerated plaques had higher ΔT compared to irregular and regular plaques (2.2±0.53 vs 1.32±0.21 vs 0.96±0.19°C accordingly, p<0.01). Heterogeneous plaques had higher ΔT compared to homogenous (1.52±0.53 vs 0.83±0.13°C, p<0.01). All patients with high ΔT (≥1) showed significant CAD on coronary angiography, whereas only 10% (n=3) of patients from this group had low ΔT value (<1).
Conclusions: Microwave radiometry reveals as a feasible and safe method for the assessment of the functional characteristics of carotid plaques. Further studies are needed to validate this method as an additional tool for the prediction and/or exclusion of CAD.
- © 2011 by American Heart Association, Inc.