Noninvasive Assessment of Carotid Plaques Calcification by F-Sodium Fluoride Accumulation: Correlation with Pathology.

Backgroud: Vascular calcification is currently recognized as an important pathobiological process in atherosclerosis, but the mechanism remains elusive. Given the similarities in vascular calcification and bone formation, F-sodium fluoride (F-NaF) is now considered a novel marker of vascular calcification. This study aimed to correlate F-NaF accumulation with the histological characterization of vascular calcification in carotid plaques.

Methods: A total of 8 patients who were undergoing carotid endarterectomy (CEA) for carotid artery stenosis were recruited. Before CEA, F-NaF positron emission tomography and computed tomography (PET-CT) studies were conducted. F-NaF uptake was measured by the maximum standardized uptake value and the target-to-background ratio. The Hounsfield unit (HU) value was also measured. Postoperative carotid plaques were investigated by hematoxylin and eosin staining, alizarin red staining, and immunohistochemistry (alpha-smooth muscle actin and CD68).

Results: F-NaF uptake was observed in the bilateral carotid bifurcation of all patients. Compared with the pathology results, there was a significant correlation between tracer activity in the carotid plaques and the calcification in the corresponding histological sections (integrated optical density [IOD]: r = .781, P = .022; positive area: r = .765, P = .027). A negative correlation was observed between F-NaF uptake and smooth muscle cell staining (IOD: r = -.710, P = .049). F-NaF uptake did not correlate with carotid artery stenosis, HU value, or inflammation.

Conclusions: F-NaF PET-CT is a noninvasive imaging method for the assessment of calcification in human carotid atherosclerotic plaques and a promising approach to studying calcification in atherosclerotic lesions.