MRI-Detectable Focal Lesions (FL) in Multiple Myeloma (MM) at Relapse Frequently Involve Novel Sites Not Involved at Diagnosis.

Macrofocal lesions (FL) in the medullary space are a hallmark of mm readily detected by MRI scans, both at diagnosis and at relapse. In this study we evaluated, among 25 patients enrolled in TT II, with FL at relapse and a preceding clinical CR (by M protein and marrow examinations) the relationship to presence and location of FL at diagnosis. On relapse, 17/25 (68%) had fewer FL, 5/25 (20%) had the same number of FL, 3/25 (12%) had more FL than on baseline examination. There was a general trend for the larger FL at baseline to still be present on relapse (Table 1). Despite the trend to fewer focal lesions on relapse compared to baseline, 11/25 (44%) of patients presented with FL in new sites that were not present on baseline. Finally, in relapsing patients, 4/25 (16%) presented with new sites of extramedullary tumor (EMD). These data establish that although there are usually fewer MRI-defined FL on relapse than on baseline examination, the vast majority of FL on relapse represent new areas of macrofocal disease that were not present at diagnosis.

MRI FL Persisting from Baseline to Relapse (n=25)