Fatty meal prior to FDG PET/CT could improve coronary plaque imaging

A new protocol nuclear cardiologists could use to improve identification of coronary plaques involves decreasing F-18 FDG myocardial uptake to reveal more coronary detail in cardiac PET/CT. A high-fat meal prior to fasting seems to do the trick, according to a study published July 31 in the Journal of Nuclear Medicine.

Researchers including Fabian Demeure, MD, from the University of Louvain in Louvain-La-Neuve, Belgium, evaluated this technique by setting up four different modes of intervention to see which would have the best effect on myocardial uptake suppression in this randomized, prospective trial. The question of whether circulating free fatty acids (cFFA) had an effect on FDG uptake was also explored.

For this study, 36 subjects were instructed to eat a high-fat, low-carbohydrate meal before a 12-hour fast. The participants were then randomly placed into one of the four intervention groups. One group received verapamil as a calcium channel blocker. Two groups were administered either 50 mL of olive oil or 43.8 g of lipids one hour before FDG PET/CT. A final control group received no additional intervention than the high-fat meal.

Results of the study showed effective suppression of myocardial FDG in eight out of nine subjects who received no additional intervention. Those numbers were the same for the group who also received calcium blockers. A total of five out of nine subjects who received the high-fat lipid solution one hour before imaging showed effective suppression and four out of nine subjects showed effective suppression after receiving olive oil prior to imaging. These results indicate that none of the additional interventions provided any benefit over and above the high-fat meal prior to fasting.

The authors of the study also found that cFFA levels were significantly higher in those who showed good suppression of myocardial FDG uptake. A receiver-operating-characteristic curve analysis found that 0.65 mmol/L cFFA is the best cutoff value as a predictor of good FDG uptake suppression. That positive predictive value was gauged at 89 percent.

"A high-fat low-carbohydrate meal followed by a 12-hour fasting period effectively suppressed myocardial F-18 FDG uptake in most subjects, " the authors concluded. "Neither complementary fatty acid loading nor verapamil administered one hour before F-18 FDG injection conferred any additional benefit. F-18 FDG uptake was inversely correlated with cFFA level, representing an interesting way to predict myocardial F-18 FDG uptake suppression."