Abstract
Purpose: To evaluate whole-body MRI (WB-MRI) parameters for treatment response prediction in multiple myeloma (MM). Materials and Methods: Twenty-one MM patients underwent WB-MRI at diagnosis and after 2 cycles of chemotherapy. Scans acquired at 3.0T included T2, diffusionweighted- imaging (DWI) and mDixon pre- and post-contrast. Twenty focal lesions (FLs) matched on DWI and enhanced mDixon were selected for each time point. Estimated tumour volume (eTV), apparentdiffusion- coefficient (ADC), enhancement-ratio (ER) and signal fat fraction (sFF) were derived. Clinical treatment response to chemotherapy was assessed using conventional criteria. Significance of temporal parameter change was assessed by the paired t-test and receiver operating characteristics/area under the curve (AUC) analysis was performed. Parameter repeatability was assessed by interclass correlation (ICC) and Bland-Altman analysis of 10 healthy volunteers scanned at two time-points. Results: 15/21 patients responded to treatment. Of 254 FLs analysed, sFF (p<0.0001) and ADC (p=0.001) significantly increased in responders but not non-responders. eTV significantly decreased in 20/21 cases. Focal lesion sFF was the best predictor of treatment response (AUC 1.0). Bone sFF repeatability was excellent (ICC 0.98 ) and better than bone ADC (ICC 0.47). Conclusion: WB-MRI derived focal lesion sFF shows promise as an imaging biomarker of treatment response in newly diagnosed MM.