Role of whole-body diffusion-weighted imaging in evaluation of multiple myeloma

The evaluation of bone disease in multiple myeloma (MM) is an important topic in imaging. This study retrospectively investigated whole-body diffusion-weighted imaging (WB-DWI) in the evaluation of bone marrow infiltration and treatment response in MM.A total of 126 patients with MM who underwent WB-DWI between January 2016 and December 2020 were enrolled. All the patients received 4-course induction chemotherapy. WB-DWI was performed before and after chemotherapy to measure the apparent diffusion coefficient (ADC) values. According to gender and Revised International Staging System (RISS) staging groups, the relationship between ADC value and bone marrow plasma cell infiltration ratio before treatment were explored using Spearman and Pearson correlation coefficients. Comparison of ADC values before and after treatment according to different chemotherapy regimens and treatment response was performed by 2-independent samples non-parametric tests and t test.There was a negative correlation between the ADC value and the degree of bone marrow infiltration and this was statistically significant (r = -0.843, P < .001). In different gender and RISS groups, ADC value before treatment was negatively correlated with the proportion of plasma cell infiltration (male, r = -0.849; female, r = -0.836; Stage I, r = -0.659; Stage II, r = -0.870; Stage III, r = -0.745; all P < .001). The ADC values of all subjects increased to varying degrees after 4-course induction chemotherapy, including different chemotherapy regimens and treatment responses (all P < .05 except for progressive disease group).The ADC value was negatively correlated with the degree of bone marrow infiltration in different gender and RISS stages. The ADC value increased after treatment, but it was not consistent with progressive disease group. The increase of ADC value may indicate the disease burden and outcome of MM induced chemotherapy.