Suppression of myocardial 18F-FDG uptake by preparing patients with a high-fat, low-carbohydrate diet

OBJECTIVE. Myocardial F-18-FDG uptake in PET scans in patients prepared by the usual fasting protocol may result in difficulties in interpretation because variable uptake may yield false-positive results regarding mediastinal abnormalities. We aimed to analyze, retrospectively, the effect of diet on myocardial FDG uptake. MATERIALS AND METHODS. The "fasting" group comprised 101 consecutive patients before a clinical change in the patient preparation protocol. The "new diet" group comprised 60 consecutive patients after the clinical protocol change who were directed to consume a very high-fat, low-carbohydrate, protein-permitted (VHFLCPP) diet before FDG injection. All patients were given a questionnaire that was used to verify diet adherence. Non-adherers or patients failing to complete questionnaires were excluded from analysis. Myocardial uptake was evaluated by measuring the maximum standardized uptake value (SUVmax) in areas defined by CT as being cardiac. RESULTS. The average SUVmax for the fasting group (n = 101) was 8.8 +/- 5.7, and the average SUVmax for the VHFLCPP group (n = 60) was 3.9 +/- 3.6. The one-tailed Student's t test yielded a p value of < 0.00001. CONCLUSION. A VHFLCPP meal eaten 3-6 hours before FDG injection suppresses myocardial FDG uptake. This should facilitate definition of mediastinal abnormalities on FDG PET, particularly with stand-alone PET. Furthermore, this patient preparation protocol may permit the detection of biologically active coronary artery disease.