Abstract 2022: Non Invasive Molecular Imaging of Inflammation/Apoptosis with 99mTc-Annexin A5 reveals Plaque Instability in Patients With Significant Carotid Artery Stenosis.
Introduction Apoptosis and inflammation constitute important substrates of atherosclerotic plaques that are vulnerable to result in acute events such as Stroke, TIA or Myocardial Infarction and can be non-invasively imaged with 99mTc-Annexin A5 (TAA5). We evaluated the role of TAA5 imaging in patients who had suffered from recent or remote cerebrovascular accidents, scheduled for carotid endarterectomy (CEA). We hypothesized that TAA5 uptake would correlate with histology findings in carotid artery plaques.
Materials & Methods Sixteen patients underwent radionuclide imaging. All patients had ultrasonic/CT evidence of significant carotid artery stenosis and had CEA one day after imaging. SPECT imaging of the cervical region was performed after IV administration of 15–30 mCi TAA5. CEA specimens were collected during surgery and analyzed for AA5 content and plaque histology.
Results Significant TAA5 uptake was observed in culprit carotid vessel in 4 patients. In all these cases, histologic characteristics were suggestive of plaque instability, including large necrotic cores, macrophage infiltration and presence of AA5. In 10 patients no TAA5 uptake was seen, which correlated in 9 cases with the histologic characteristics of stable atherosclerotic disease, characterized by smooth muscle-rich lesions. In 2 cases with equivocal TAA5 uptake, unstable histologic features were observed.
Discussion & Conclusion These data indicate that enhanced uptake of TAA5 in the carotid artery region reflects plaque instability. Therefore, non-invasive imaging with TAA5 could offer a valuable tool for the detection of plaque instability in carotid artery disease.