**3. Non 18F-FDG PET Tracers in MM**

Due to the limitations of 18F-FDG as an imaging biomarker of MM, several other PET tracers have been proposed and tested in patients with the malignancy. Although some of them have given promising results regarding detection of MM lesions, most studies were performed in rather small patient cohorts and, thus, require validation in further prospective clinical trials. The most important of them will be addressed in the following paragraphs.
