Abstract 12561: Imaging Intraplaque Inflammation in Carotid Atherosclerosis With 11C-PK11195 PET/CT
Background: Intraplaque inflammation plays an important role in the progression and destabilization of atherosclerotic plaques. We sought to determine whether intraplaque inflammation could be measured with positron emission tomography/computed tomography angiography (PET/CTA) using 11C-PK11195, a selective ligand for the peripheral benzodiazepine receptor (PBR) which is highly expressed in activated macrophages.
Methods and Results: Patients (n=32) with carotid stenosis (9 symptomatic and 23 asymptomatic, mean age 70±9 years) underwent 11C-PK11195 PET/CTA imaging. 11C-PK11195 uptake into carotid plaques was measured using standardized uptake values and target-to-background ratios (TBR) (normalized to venous blood). On CTA images, plaque composition was assessed by measuring CT attenuation of the carotid plaque (Hounsfield Units, HU). 11C-PK11195 TBR values were higher in symptomatic compared to asymptomatic patients (1.06±0.20 versus 0.86±0.11, p=0.008). On CTA, symptomatic plaques had a lower attenuation than asymptomatic plaques (46±31 versus 86±44 HU, p=0.001). Both TBR and CT plaque attenuation had high negative predictive values (87%, and 92%, respectively) for detecting symptomatic patients. However, the best positive predictive value (100%) was achieved when TBR and CT attenuation were combined.
Conclusions: Imaging intraplaque inflammation in vivo with 11C-PK11195 and PET combined with CTA is feasible and can help distinguishing between recently symptomatic and asymptomatic plaques. Plaques with low CT attenuation and increased 11C-PK11195 uptake seem to be those at highest risk of thromboembolic events.
- © 2010 by American Heart Association, Inc.