Impact of Whole-Body Magnetic Resonance Imaging on Staging in Patients with Newly Diagnosed Plasma Cell Disease.

INTRODUCTION: MRI has a high sensitivity in determining changes in bone marrow induced by metastatic disease or primary neoplasms of the bone marrow. Whole-Body Magnetic Resonance Imaging (WB-MRI) is a novel imaging technique that displays nearly the complete skeletal system in one exam. We investigated the differences between conventional skeletal survey and WB-MRI and their impact on staging of patients with newly diagnosed plasma cell disease.

METHOD AND MATERIALS: In 41 consecutive patients with newly diagnosed MGUS (n=5), Multiple Myeloma (n=34) or AL-Amyloidosis (n=2) conventional radiographs and WB-MRI (coronar T1 tse and T2 tirm sequences and sagittal T2 star sequences, 1,5 T MRI with parallel imaging, Siemens Avanto®) were performed. Radiographs and scans were evaluated for diffuse and focal bone marrow involvement in consent by two experienced radiologists blinded for patient name and study time. Staging was performed including clinical data according to the Salmon/Durie classification system and the Durie/Salmon PLUS classification system with inclusion of WB-MRI.

RESULTS: In 24 (59%) patients there were no lesions in conventional radiography or MRI. In 17 (41 %) patients results of MRI and conventional radiography were discrepant. 4 (10%) patients had lesions only in MRI, 3 (7%) only in conventional radiography and 10 (24%) in both techniques but in different localization. In 16 (38%) patients with radiological signs of osteopenia there was no diffuse infiltration in MRI or vice versa. We systematically analysed the consequences of WB-MRI on staging of patients based on the newly proposed staging system Durie/Salmon PLUS. Replacing conventional radiographs by WB-MRI resulted in reclassification of 12 patients. 3 patients were reclassified from MGUS or stage I into stage II or III. 9 patients were downstaged from stage III or II into stage I or MGUS.

CONCLUSION: WB-MRI is a valuable technique for the initial work-up of patients with Multiple Myeloma. In comparison with conventional skeletal survey there are often differing results with impact on clinical staging and influence on therapy decision. WB-MRI can give additional information in patients with unclear staging situation before onset of therapy. Further evaluation of WB-MRI within prospective studies is warranted in particular with respect to prognostic impact regarding overall prognosis as well as regarding local complications. Until then WB-MRI should be used complementary to conventional radiography or CT-techniques that provide accurate imaging of the bone.