Appearance of Monoclonal Plasma Cell Diseases in Whole Body MRI in 544 Patients and Correlation with Parameters of Disease Activity

Abstract 4966

Focal lesions (FL) and diffuse tumor cell infiltration detected by whole body MRI (WB-MRI) have been demonstrated to be of prognostic significance for predicting progression free and overall survival in patients with monoclonal plasma cell diseases. In this trial we have assessed 544 unselected and untreated patients: 138 with monoclonal gammopathy of undetermined significance (MGUS), 157 with smoldering myeloma (SMM), and 249 with multiple myeloma (MM). WB-MRI was performed on two identical 1. 5 Tesla MRI-scanners with body array curls. Assessment of FL was done by two experienced radiologists blinded to the diagnosis of the patients in consensus. We found focal lesions in 23. 9%, 34. 4%, and 80. 3% of patients with MGUS, SMM and MM, respectively, and a diffuse infiltration was detected in 38. 4%, 45. 9%, 71. 5% of the corresponding patients. The differences between MGUS, SMM and MM patients were statistically significant (p<0. 0001). The presence of FL as well as the presence of a diffuse infiltration was correlated with an increased plasma cell percentage in bone marrow (p<0. 0001) and monoclonal protein concentration (p=0. 001). Further categorization of the diffuse infiltration patterns in WB-MRI into minimal, moderate, severe and “salt&pepper” patterns, was able to identify a significant correlation between both M-protein and plasma cell percentage in bone marrow as well as age. In MGUS and SMM patients, FL were more often detected in patients with a diffuse background, while in MM patients, FL were present at the same rate across the diffuse infiltration subgroups. In summary bone marrow infiltration in WB-MRI is significantly different between stages of plasma cell disease and correlates with established markers of disease activity.