Variances of dietary preparation for suppression of physiological 18F-FDG myocardial uptake in the presence of cardiac sarcoidosis: a systematic review

Background: F-fluorodeoxyglucose (F-FDG) positron emission tomography (PET) is used in the diagnosis and management of patients with cardiac sarcoidosis (CS). Various preparation protocols have been proposed to minimise myocardial F-FDG uptake and improve scan readability. The aim of this systematic review was to identify the optimal dietary prescription for suppression of physiological F-FDG myocardial uptake to enhance clinical diagnosis of CS. Methods and Results: MEDLINE and PubMed databases identified 13 studies meeting inclusion criteria for review. Articles were assessed using the Australian National Health and Medical Research Council levels of evidence and categorised as sarcoidosis (human) or non-sarcoidosis (human, animal). Visual uptake scales (qualitative) and/or standardised uptake values (SUV) (quantitative) were used in all the studies reviewed. Nine of 11 human studies showed statistically significant improvements in PET scan interpretation with carbohydrate-restricted diets compared with fasting only, and when carbohydrates were restricted for a longer period of time. Two animal studies showed statistically significant improvements following very low carbohydrate diet preparation (0.01% and 0.4% carbohydrate diets) compared with higher carbohydrate diets. Conclusions: Variation in measures used, dietary prescriptions, fasting times, species and study quality makes result comparison and applicability difficult. Definitive dietary recommendations are not possible based on current evidence