Comparison Between FDG-PET and MRI for the Assessment of Response to Intensive Chemotherapy in Multiple Myeloma Patients.

First whole body FDG-PET scan and MRI before the start of the treatment. Second whole body FDG-PET scan and MRI after the end of the treatment. On a basis of patient, comparison between PET and MRI will be done tumoral site by site. Sensitivity, Specificity will be estimated for both techniques. In case of discrepancy, another imaging method or biopsy (if easy to perform) will be serve as standard of reference. Kappa coefficients and Mc Nemar test will be performed to compare the two methods. FDG = fluorodeoxyglucose FLUCIS® (Schering-CisBio® international)