Use of 2-[18F]-fluoro-2-deoxy-d-glucose positron emission tomography (FDG PET) imaging for the evaluation of muscle metabolic activity in ruptured rotator cuffs: Identification of shoulder muscles by fusion imaging studies involving both FDG PET and magnetic resonance imaging.

The uptake of 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) into shoulder muscles was studied in 11 patients with rotator cuff tears. FDG was injected under resting conditions, and cuff muscle exercises were performed followed by evaluation of the standardized uptake value (SUV) in shoulder muscles bilaterally. Analysis was performed with a subtracted SUV, obtained by subtracting the SUV of the muscle at rest from that after exercise. Fusion imaging studies involving FDG positron emission tomography (PET) and magnetic resonance imaging would provide a novel strategy with the potential of improving on the limited resolution of PET images. In this study this relatively new strategy revealed a similar decrease in the supraspinatus SUV in cases involving both complete and partial tears. The SUV in the infraspinatus and subscapularis also decreased, regardless of whether these muscles were intact or ruptured; the SUV in the deltoid remained basically unchanged. With the use of this exercise protocol, FDG PET might prove useful for objective evaluation of rotator cuff muscle activity.