Longitudinal analysis of atherosclerotic plaques evolution: an ¹⁸F-NaF PET/CT study

Purpose: ¹⁸F-NaF-PET/CT can detect mineral metabolism within atherosclerotic plaques. To ascertain whether their ¹⁸F-NaF uptake purports progression, this index was compared with subsequent morphologic evolution.

Methods: 71 patients underwent two consecutive ¹⁸F-NaF-PET/CTs (PET1/PET2). In PET1, non-calcified ¹⁸F-NaF hot spots were identified in the abdominal aorta. Their mean/max HU was compared with those of a non-calcified control region (CR) and with corresponding areas in PET2. A target-to-background ratio (TBR), mean density (HU), and calcium score (CS) were calculated on calcified atherosclerotic plaques in PET1 and compared with those in PET2. A VOI including the entire abdominal aorta was drawn; mean TBR and total CS were calculated on PET1 and compared with those PET2.

Results: Hot spots in PET1 (N = 179) had a greater HU than CR (48 ± 8 vs 37 ± 9, P < .01). Mean hot spots HU increased to 59 ± 12 in PET2 (P < .001). New calcifications appeared at the hot spots site in 73 cases (41%). Baseline atherosclerotic plaque's (N = 375) TBR was proportional to percent HU and CS increase (P < .01 for both). Aortic CS increased (P < .001); the whole-aorta TBR in PET1 correlated with the CS increase between the baseline and the second PET/CT (R = .63, P < .01).

Conclusions: ¹⁸F-NaF-PET/CT depicts the early stages of plaques development and tracks their evolution over time.