Multiple myeloma treatment response assessment with whole-body dynamic contrast-enhanced MR imaging

Purpose: To compare posttreatment bone marrow changes at whole-body dynamic contrast material-enhanced magnetic resonance (MR) imaging with clinical response in patients with multiple myeloma (MM) and to determine if this technique can be used to assess treatment response in patients with MM. Materials and Methods: This study was approved by an institutional review board; all patients gave informed written consent. Thirty patients (21 men, nine women;mean age, 58 years 6 10 [standard deviation]) underwent whole-body dynamic contrastenhanced MR imaging before treatment, after induction chemotherapy (n = 30), and after autologous stem cell transplantation (ASCT) (n = 20). Maximal percentages of bone marrow(BME_max) and focal lesion (FLE _max) enhancement were assessed at each MR imaging examination. Clinical responses were determined on the basis of international uniform response criteria. Posttreatment changes in BME_max and FLE _max were compared with clinical response to therapy by using the Mann-Whitney U test. Receiver operating characteristic (ROC) analysis of posttreatment BME_max was used to identify poor responders. Results: Eleven of 30 patients were good responders to induction chemotherapy; 16 of 20 patients were good responders to ASCT. After induction chemotherapy, mean BME_max differed between good and poor responders (94.3% vs 138.4%, respectively; P =.02). With the exclusion of results from six examinations with focal lesions in which a poor clinical response was classified but BME _max had normalized, a posttreatment BME_max of more than 96.8% had 100% sensitivity for the identification of poor responders (specificity, 76.9%; area under the ROC curve, 0.90; P = .0001). Mean FLE _max after induction chemotherapy did not differ between good and poor responders. Mean timing(ie, the number of postcontrast dynamic acquisitions where FLE_max was observed) was significantly delayed in good responders compared with poor responders(4.7 vs 2.9, P,.0001). Post-ASCT MR imaging results correctly depicted all four clinically good responders whose disease subsequently progressed. Conclusion: With quantitative analysis of BME_max and the timing of FLE_max, whole-body dynamic contrast-enhanced MR imaging can be used to assess treatment response in patients with MM.