Carotid Artery Plaque

The goal of this observational study, called OMICA (Oral Microbiome in Carotid Atherosclerosis), is to learn how bacteria living in the mouth may influence the development and stability of plaques in the carotid arteries, which supply blood to the brain. Plaque buildup in these arteries can lead to stroke. Researchers want to understand whether certain oral bacteria are linked to plaque vulnerability, meaning a higher chance that the plaque will rupture and cause a stroke. The study will include a cohort of adults scheduled for carotid endarterectomy at Semmelweis University. Participants will be enrolled in the Semmelweis University Carotid Biobank project. The main questions the study aims to answer are: Do people with more severe gum disease or tooth infection have a higher number of bacteria in their carotid plaques, and are those plaques more likely to rupture? Are the bacteria found in vulnerable plaques different from those in stable plaques? Are similar bacteria found in the mouth, gut, and plaques, suggesting that bacteria may travel through the body? What participants will do: Have their oral health checked before surgery, including an exam of gum disease and tooth infections. Provide microbiome samples from the mouth, anus, urine, and carotid plaque (taken during surgery). Have preoperative photon-counting computed tomography (CT) performed to assess plaque stability and study eligibility. All samples and imaging data will be analyzed to identify bacterial species and their relationship to plaque type. The study does not involve any experimental treatment or medication. Participation adds no significant medical risk beyond standard care. Researchers will compare bacterial patterns between people with vulnerable plaques and those with stable plaques to identify microbial signatures linked to carotid plaque instability. The results may help create future microbiome-based risk models for detecting people at higher risk of stroke or severe atherosclerosis.

Carotid atherosclerotic plaque rupture is the main cause of ischemic stroke attacks, and early and precise assessment of plaque vulnerability can prevent ischemic stroke. High-resolution MRI can reflect vulnerable plaque features such as thin fibrous caps and large lipid cores, but cannot assess their metabolic information; Fibro-activated proteins (FAPs) of PET are specifically expressed in atherosclerosis and suggest vulnerable plaques by reflecting inflammation-induced fibrosis. The aim of this study was to apply 18F FDG\&68Ga-FAPI PET/MR imaging to investigate the vulnerability of carotid atherosclerotic plaques, to obtain quantitative evaluation indexes of active fibrosis within carotid plaques, and to clarify the PET/MR characteristics of unstable plaques in carotid arteries

This clinical trial aims to evaluate whether \[¹⁸F\]AlF-OC PET/MRI can characterize and quantify inflammation in carotid atherosclerotic plaques. The study will assess if tracer uptake in culprit and non-culprit carotid arteries, measured by standardized uptake values (SUV), is associated with future cerebrovascular events. Specifically, it will examine whether \[¹⁸F\]AlF-OC uptake predicts the risk of recurrent ipsilateral TIA, amaurosis fugax, stroke, or other vascular complications. Participants will undergo \[¹⁸F\]AlF-OC PET/MRI and will be followed via telephone interviews at 90 days, 1 year, and 3 years after their initial stroke or TIA.

While 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging has been used as an early marker of drug efficacy in numerous clinical cardiovascular drug trials, as a glucose analog, its signal in the vasculature lacks inflammatory cell-specificity. Moreover, high background 18F-FDG signals from the myocardium often preclude coronary artery imaging, despite attempts to suppress myocardial tracer uptake by dietary manipulation. These limitations of 18F-FDG for measuring changes in vascular inflammation arising from drug intervention highlight important unmet needs, which might be overcome by using a somatostatin receptor subtype-2 (SST2) PET tracer.