The Effect of Diffuse Muscle Uptake on SUVmax Levels in 18F-FDG PET/CT Imaging

INTRODUCTION: The aim of this study is to evaluate diffuse skeletal muscle uptake, which is a factor affecting the distribution of 2-[18F]-Fluoro-2-deoxy-D-glucose (FDG) in the body, and its effect on the SUVmax level of malignant lesions.
METHODS: Twenty-two patients (M/F=12/10) who underwent positron emission tomography-computed tomography (PET/CT) PET/CT scans with FDG and showed diffuse muscle uptake, and whose FDG PET/CT scans were appropriately repeated, were enrolled in the study. Maximised standardised uptake value (SUVmax) levels of malignant foci and normal liver parenchymal activity were measured in images with diffuse muscle uptake and normal uptake. The change in the SUVmax levels of the lesions between the two studies was calculated.
RESULTS: The mean dose of FDG administered to patients in each study was 248.7 (248.7±56.2) megabecquerels. When both images were compared, it was calculated that there was a 38.6% (Std. Deviation 18.7/min: 9%, max: 83%) change in the SUVmax level of the same lesion. While the mean rate of change in the lesion/liver SUVmax ratio for the same lesion was 31%, the median level was recorded as 29.4%.
DISCUSSION AND CONCLUSION: SUVmax and image quality are significantly affected by diffuse muscle uptake. For this reason, the study should be repeated with FDG PET/CT scans in diffuse muscle involvement.