18F-NaF uptake on vascular PET imaging in symptomatic versus asymptomatic atherosclerotic disease: A meta-analysis.

Introduction: ¹⁸F-sodium fluoride (NaF) positron-emission tomography (PET) is increasingly being used to measure microcalcification in atherosclerotic disease in vivo. Correlations have been drawn between sodium fluoride uptake and the presence of high-risk plaque features, as well as its association with clinical atherosclerotic sequelae. The aim of this study was to perform a meta-analysis of NaF uptake on PET imaging and its relation to symptomatic and asymptomatic disease.

Methods: A systematic review was performed according to PRISMA guidelines, via searching the Ovid MEDLINE, Ovid Embase, Cochrane Library, PubMed, Scopus, and Web of Science Core Collection databases up to May 2024. The search strategy included the terms 'NaF', 'PET', and 'plaque', and all studies with data regarding the degree of microcalcification, as measured by ¹⁸F-NaF uptake in symptomatic and asymptomatic atherosclerotic plaques, were included. Analysis involved calculating mean differences between uptake values and comparison using a random-effects model.

Results: A total of 16 articles, involving 423 participants, were included in the meta-analysis (10 carotid artery studies, five coronary artery studies, and one in peripheral vascular disease). Comparing ¹⁸F-NaF uptake in symptomatic versus asymptomatic atherosclerotic plaques, a mean difference of 0.43 (95% CI 0.29 to 0.57; p < 0.0001, I² = 65%) was noted in studies comparing symptomatic and asymptomatic plaques in the same participant, with a significant difference in effect based on arterial territory studied (χ² = 12.68, p = 0.0018). In studies of participants with and without symptomatic disease, there was no significant difference between symptomatic and asymptomatic plaques (mean difference 0.27, 95% CI -0.26 to 0.80, p = 0.28, I² = 85%).

Conclusions: PET imaging using ¹⁸F-NaF can detect differences in microcalcification between symptomatic and asymptomatic atherosclerotic plaques within, but not between, individuals, and thus, is a marker of symptomatic disease. The standardization of ¹⁸F-NaF PET imaging protocols, and its future use as a risk stratification tool or outcome measure, requires further study. (PROSPERO Registration ID: CRD42023451363).