Magnitude of serum β-hydroxybutyrate elevations and myocardial glucose suppression in fluorine-18 fluorodeoxyglucose positron emission tomography for cardiac sarcoidosis.

This retrospective cohort study evaluated the relationship between serum β-hydroxybutyrate (BHB) levels and myocardial glucose suppression in 74 patients undergoing fluorine-18 fluorodeoxyglucose positron emission tomography for suspected cardiac sarcoidosis. The average BHB concentration prior to FDG administration was 0.94 ± 0.78 mmol/L. The septal-to-blood pool uptake ratio (SUVmax_septal/SUVmean_blood pool) ranged from 0.50 to 0.88, with a median of 0.66 (Quartile 1 = 0.58; Quartile 3 = 0.73). No significant association was found between BHB levels and the septal-to-blood pool uptake ratio (r = 0.09; P = 0.48), suggesting a metabolic plateau regarding myocardial glucose utilization once adequate ketosis is achieved. These preliminary findings support a threshold effect rather than a dose-dependent relationship between serum BHB levels and myocardial glucose suppression following appropriate dietary preparation.