Impact of carbohydrate restriction with and without fatty acid loading on myocardial ¹⁸F-FDG uptake during PET: A randomized controlled trial

Low-carbohydrate (LC) and high-fat, low-carbohydrate (HFLC) dietary preparations may enhance ¹⁸F-FDG-PET-based imaging of small, inflamed structures near the heart by suppressing myocardial FDG signal. We compared myocardial ¹⁸F-FDG uptake in patients randomized to LC, HFLC, and unrestricted (UR) preparations prior to ¹⁸F-FDG-PET.

We randomized 63 outpatients referred for oncologic ¹⁸F-FDG-PET to LC, HFLC, or UR dietary preparations (1:1:1 allocation) starting the evening before PET. After eating dinner according to instructions, UR and LC patients fasted until FDG injection (mean time 745 minutes for UR, 899 minutes for LC), and HFLC patients drank a fatty drink 60-70 minutes prior to FDG injection. Attenuation-corrected PET imaging was performed 60 minutes after FDG administration. Maximal myocardial standard uptake values (MyoSUV_max) were systematically measured in axial view and compared between the three groups. Using UR patients as reference, mean MyoSUV_max was lower in LC patients (3.3 ± 2.7 vs 6.2 ± 5.2, P = .03) but not in HFLC patients (5.5 ± 4.2, P = .63). Ratios of MyoSUV_max to liver SUV_max, calculated to control for background uptake, were not significantly different amongst the groups (1.9 ± 2.1 LC, 2.6 ± 2.3 HFLC, 3.6 ± 3.5 UR).

In this small randomized controlled trial using UR diet as reference, LC dietary preparation followed by extended fasting resulted in significant myocardial uptake suppression.