The effects of muscle exercise and bed rest on [18F]methylcholine PET/CT.

Purpose: This study evaluated the impact of limited and strenuous physical exercise on [(18)F]methylcholine uptake in muscle.

Methods: Ten consecutive patients participated, three of whom had strict bed rest, three were allowed to walk around and four performed strenuous single arm exercise by lifting a 7.5-kg weight. [(18)F]Methylcholine uptake was measured in the biceps and gluteus muscles on both sides.

Results: Strenuous exercise resulted in a 202% increase in [(18)F]methylcholine uptake in the activated biceps muscle as well as a 112% increase in muscle groups used to retain body position. This resulted in asymmetrical images that were visually less easy to interpret. In walking patients there was a more limited increase in biceps (45%) and gluteus (74%) muscle uptake, without visually recognizable differences.

Conclusion: Strenuous exercise may result in a considerable increase in [(18)F]methylcholine uptake in muscle and should be avoided prior to imaging. Strict bed rest does not seem to be required. Tracer injection while resting on the scanner remains a safe approach.