Application of [18F]-fluorodeoxyglucose PET/computed tomography to measure volume and metabolic activity of arm muscles.

Objective: This study aimed to introduce a computed tomography (CT)-based tissue segmentation technique to quantify the volume and metabolic activity of the arm muscles using [18F]-fluorodeoxyglucose ([18F]FDG) PET/CT.

Methods: Eighty-seven subjects from the CAMONA study were included. A semiautomated three-dimensional segmentation algorithm was used to highlight the muscle. The [18F]FDG uptake was measured as mean standardized uptake value (SUV) normalized to body weight (SUVBW) and to lean body mass (SUVLBM). To acquire normalized volume, arm muscle volume, humerus volume, and humerus length were used. The average SUVmean was calculated from independently measured volumes (cm3) of the left and right muscle groups. The obtained SUVBW, SUVLBM, and normalized volume were used to compare the right and left arms.

Results: Between right and left arm muscles, there was significantly higher uptake of SUVBW and SUVLBM in the right arm compared with the left (P < 0.001). Between males and females, there was a significantly higher SUVBW in the right arm for females (P = 0.03) and significantly higher normalized volume on both right and left arms for males (right, P < 0.001; left, P < 0.001).

Conclusion: [18F]FDG PET/CT using CT-based segmentation enables analysis of total arm muscle metabolic activity and volume. This methodology demonstrated significant differences in mean SUVBW and SUVLBM between the left and right arms, with consistently higher uptake in the right arm. In addition, females exhibited higher SUVBW than males. The techniques developed in this study may also be applied to further investigate the laterality and metabolism of other muscle groups.