Determinants of intracranial microcalcification assessed by 18F-sodium fluoride PET

PURPOSE: Intracranial calcifications are commonly found in adults and may represent either benign or pathological lesions. Conventional imaging modalities detect static macrocalcifications but do not capture molecular microcalcification. In this study, we used 18 F-sodium fluoride (NaF) PET/computed tomography (CT) to idetect intracranial molecular microcalcification. METHODS: A total of 127 subjects underwent 18 F-NaF PET/CT 90 min following radiotracer injection. Artificial intelligence-based quantification was performed to obtain regions of interest for the brainstem, basal ganglia (caudate and lentiform nuclei), insula, thalamus, and ventricles. Linear regression models were used to correlate NaF mean standardized uptake value (SUV mean ) with various clinical factors. RESULTS: NaF SUV mean was highest in the insula (0.8 ± 0.4) and brainstem (0.8 ± 0.3), while uptake was lowest in the caudate nucleus (0.1 ± 0.1). No differences were found in NaF SUV mean between healthy volunteers and at-risk patients. On multivariate regression, NaF SUV mean directly correlated with age in the brainstem ( β = 0.01, P = 0.01), lentiform nucleus ( β < 0.01, P = 0.02), and ventricles ( β < 0.01, P < 0.01). Male sex inversely correlated with NaF SUV mean in the insula ( β = -0.30, P < 0.01). There was an association between NaF SUV mean and BMI in the brainstem, caudate nucleus, lentiform nucleus, thalamus, and ventricles ( β ≤ 0.01, P < 0.01 in all regions). Thalamic and ventricular NaF SUV mean directly correlated with hypertension on univariate but not multivariate analysis. CONCLUSION: NaF PET/CT detects intracranial molecular microcalcification that is not visible on conventional CT and may provide insight into pathology associated with this biological process.