High uptake of FAP may serve as a molecular marker of unstable carotid plaque biology. Published in JACC: Cardiovascular Imaging, this prospective study assessed whether 68Ga-FAPI-04 positron emission tomography/magnetic resonance imaging (PET/MRI) can identify ulcerated carotid plaques and reflect cerebrovascular risk profiles.

The analysis included 52 adults with significant carotid stenosis who underwent paired 68Ga-FAPI-04 PET/MRI and digital subtraction angiography within one week. A total of 82 plaques were evaluated for focal tracer uptake, maximum standardized uptake value, and FAPI-derived TBR. Multivariate logistic regression examined whether imaging parameters independently predicted ulceration and their relationship with clinical risk factors.

High focal FAPI uptake was observed in 35 plaques, including 18 ulcerated lesions. Ulcerated plaques had substantially higher maximum uptake and TBR compared with nonulcerated plaques (all P < 0.001). FAPI-positive uptake (P = 0.002) and FAPI-derived TBR (P < 0.001) independently predicted ulceration. TBR showed significant associations with older age and prior cerebrovascular events, and higher-risk individuals demonstrated elevated uptake values.

These findings show that FAPI-based imaging can identify active, ulceration-prone carotid plaques and may improve cerebrovascular risk assessment.