Whole-body diffusion-weighted MRI for evaluation of response in multiple myeloma patients following bortezomib-based therapy: A large single-center cohort study.

PURPOSE

To determine the feasibility of whole-body diffusion-weighted imaging (WB-DWI) MRI for evaluation of response in patients with multiple myeloma (MM) following bortezomib-based therapy and to explore the direction of apparent diffusion coefficient (ADC) changes upon treatment.

METHOD

Seventy-two MM patients who underwent WB-DWI MRI before and after bortezomib-based chemotherapy (21 weeks) were evaluated retrospectively. The estimated tumor volume (eTV) and ADC values before and after chemotherapy were calculated and compared between deep and non-deep responders. Predictive value of baseline ADC was calculated to predict the trend of ADC change following treatment.

RESULTS

Fifty-five patients were classified as deep responders, and 17 cases were assigned as non-deep responders. For 327 focal lesions (FLs), the ADC value was significantly increased from baseline to post-treatment. However, the ADC value was significantly decreased following treatment in 846 representative diffuse lesions. Diffuse lesions showed a significantly decreased ADC value in deep responders, whereas no significant variation in ADC value in FLs was found between deep and non-deep responders. Baseline ADC at a specific value (0.808 × 10  mm/s) yielded a maximum specificity (68.05%) and sensitivity (54.09%) in predicting increase of post-treatment ADC.

CONCLUSIONS

The ADC value was significantly decreased in MM patients with diffuse pattern, while it was significantly increased in those with focal pattern following bortezomib-based treatment. WB-DWI MRI could be used to discriminate deep response to induction treatment in MM patients with diffuse infiltration pattern. Baseline ADC value might have a potential to predict the trend of ADC change following treatment.