Abstract 15851: Carotid Plaque Temperatures Assessed Noninvasively by Microwave Radiometry Are Associated With Fdg-pet Uptake Values and Macrophage Infiltration by Immunohistochemistry
Introduction: 18F-FDG-PET scan is regarded the gold standard for quantification of carotid inflammation. Microwave radiometry (MWR) allows in vivo evaluation of arterial inflammation in atherosclerotic plaques by measuring temperatures.
Hypothesis: We investigated the hypothesis whether a) there is a correlation between temperature measurements by MWR and FDG-PET uptake values in patients with high-grade carotid artery stenosis, and b) carotid plaques with increased temperatures and FDG uptake values show dense macrophage infiltration and neoangiogenesis by immunohistochemistry.
Methods: Twenty-one patients scheduled for carotid endarterectomy were consecutively included in the study. FDG PET and MWR measurements of both carotid arteries were performed. Carotid FDG uptake was quantified as target to background ratio (TBR) in consecutive axial slices starting at the bifurcation and extending 2 cm superiorly and 2 cm inferiorly. Temperature differences of atherosclerotic plaques were assessed by Δτ (maximum minus minimum measured temperature across the carotid) above the respective segments. In immunohistochemistry, the intensity of CD68 (macrophage marker) and CD31 expression (microvessel density) was quantified semi quantitatively in all the operated carotid plaques (sample score >2 high, ≤2 low).
Results: There was a statistically significant positive correlation between ΔT and TBR values (R=0.40, p=0.01) for all (n=42) carotid arteries. Interestingly, correlations were stronger for the surgically operated carotid arteries (R=0.46, p=0.03). In immunohistochemistry, specimens with intense CD68 expression exhibited higher TBR and ΔT values compared to specimens with low CD68 count (1.82±0.31 vs 1.43±0.34 p=0.005 and 0.59±0.12 vs 0.52±0.19 °C, p=0.04, respectively). Carotid endarterectomy specimens with high CD31 expression had higher ΔT values compared to specimens with low CD31 expression (0.64±0.12 vs 0.52±0.13, p=0.05), but there was no significant difference in respective TBR values (p=0.78).
Conclusions: Carotid inflammation assessed by FDG uptake is associated with temperatures measured by MWR. Both measurements reflect macrophage infiltration during local inflammatory process.
Author Disclosures: G. Benetos: None. K. Toutouzas: None. I. Koutagiar: None. A. Georgakopoulos: None. G. Agrogiannis: None. E. Athanasiadis: None. G. Spyrou: None. E. Siores: None. P. Kafouris: None. E. Patsouris: None. D. Tousoulis: None. C. Anagnostopoulos: None.
- © 2016 by American Heart Association, Inc.