Vascular and plaque-specific 18-F-NaF uptake predict the atherosclerotic plaque evolution

Ziel/Aim:

18-F-NaF-PET/CT (NaF-PET) has been proposed as a tool to evaluate microscopic ongoing calcium deposition within the atherosclerotic plaque (AP). However, no study so far assessed whether NaF-PET can predict plaque evolution. In this study, we compared AP tracer uptake to its development on subsequent NaF-PET.

Methodik/Methods:

52 patients (23 females, mean age 69 ± 8 years) were retrospectively enrolled. Each patient had undergone 2 consecutive NaF-PET for clinical reasons (spaced 11 ± 2 months apart). A large VOI, encompassing the entire abdominal aorta, was drawn: mean SUV in this VOI was normalized for blood pool to obtain a target-to-background ratio (TBR). An Agaston-like calcium score (CS) was calculated on the plaques within the entire abdominal aorta. Moreover, up to five representative APs were chosen for each patient. On each one, a VOI was defined and TBR_mean, mean density (HU) and CS were calculated. These values were compared with the corresponding ones on the subsequent PET.

Ergebnisse/Results:

CS increased in all subjects (on average 1.3 ± 1% per month). There was a direct correlation between mean aorta TBR and the monthly CS increase (R = 0.78, p < 0.001). 191 plaques were identified; baseline plaque TBR_mean was correlated with the percent increase of HU (R = 0.67, p < 0.01) as well with that of CS (R = 0.89, p < 0.001). Plaques with a TBR_mean < 1.2 presented no increase in HU or in CS.

Schlussfolgerungen/Conclusions:

Measurement of uptake within the aortic wall or in the single plaque can depict ongoing calcium deposition and thus predict the calcification velocity within vascular lesions. 18-F-NaF-PET/CT could represent a new window in estimating the atherosclerotic plaque evolving potential.