I need to collect plant samples (stems, sores, etc.) to later be scanned in a micro tomograph, and I would like to know if glycerol is a good idea for a preservation medium, or can it generate interferences or artifacts during the scans
No problem with water-like or oil-like preservation material densities (related to their x-ray attenuation density).
Only if the involved densities widely differ from the specimen material, as it may happen with calcium-like or air-like preservation media, boundary artifacts may appear.