In search of the vulnerable patient or the vulnerable plaque: 18 F-sodium fluoride positron emission tomography for cardiovascular risk stratification.

Cardiovascular disease (CVD) remains a leading cause of death. Preventative therapies that reduce CVD are most effective when targeted to individuals at high risk. Current risk stratification tools have only modest prognostic capabilities, resulting in over-treatment of low-risk individuals and under-treatment of high-risk individuals. Improved methods of CVD risk stratification are required. Molecular imaging offers a novel approach to CVD risk stratification. In particular, 18 F-sodium fluoride (18 F-NaF) positron emission tomography (PET) has shown promise in the detection of both high-risk atherosclerotic plaque features and vascular calcification activity, which predicts future development of new vascular calcium deposits. The rate of change of coronary calcium scores, measured by serial computed tomography scans over a 2-year period, is a strong predictor of CVD risk. Vascular calcification activity, as measured with 18 F-NaF PET, has the potential to provide prognostic information similar to consecutive coronary calcium scoring, with a single-time-point convenience. However, owing to the rapid motion and small size of the coronary arteries, new solutions are required to address the traditional limitations of PET imaging. Two different methods of coronary PET analysis have been independently proposed and here we compare their respective strengths, weaknesses, and the potential for clinical translation.