Fig 1.
The object of each study and statistical analysis method are shown. ADC, apparent diffusion coefficient; DWIBS-MRI, diffusion-weighted imaging with body signal suppression magnetic resonance; MGUS, monoclonal gammopathy of undetermined significance; MM, multiple myeloma.
Table 1.
Demographic and clinical characteristics of patients with newly diagnosed multiple myeloma and monoclonal gammopathy of undetermined significance.
Table 2.
Treatment responses of patients who underwent diffusion-weighted imaging with body signal suppression magnetic resonance imaging (MRI) repeatedly.
Table 3.
Clinical course of patients in terms of treatment response.
Table 4.
Imaging protocols for the DWIBS experiments.
Fig 2.
Stages of plasmacytoid tumor and apparent diffusion coefficient (ADC) value.
The ADCmode was significantly higher in patients with MM than in those with MGUS (1.00 ± 0.28 ×10−3 mm2/s vs. 0.61 ± 0.38 ×10−3 mm2/s). tDV tended to be higher in patients with MM than in those with MGUS (62.3 ± 40.3 ml vs 25.9 ± 18.1 ml). MM, multiple myeloma; MGUS, monoclonal gammopathy of undetermined significance; tDV, total diffusion volume.
Fig 3.
Myeloma cell morphology and apparent diffusion coefficient (ADC) values.
The ADCmode was 1.10 ± 0.26 ×10−3 mm2/s in the mature myeloma cell type, 0.99 ± 0.40 ×10−3 mm2/s in the intermediate myeloma cell type, and 0.82 ± 0.17 ×10−3 mm2/s in the immature myeloma cell type. ADC values of the intermediate and mature cell types were significantly higher than those of the immature cell type. N:C ratio, nucleus-to-cytoplasm ratio.
Fig 4.
Durie–Salmon classification and apparent diffusion coefficient (ADC) values.
(A) The ADCmode was 1.10 ± 0.12 ×10−3 mm2/s in stage I, 1.04 ± 0.09 ×10−3 mm2/s in stage II, and 0.68 ± 0.27 ×10−3 mm2/s in stage III. (B) The ADCmode was 1.08 ± 0.27 ×10−3 mm2/s in stages I and II. ADC values of Durie–Salmon stage I and II were significantly higher than those of stage III. (C) and (D) tDV tended to be higher in Durie–Salmon stage III than in stages I and II but no significant differences were observed (stage I: 43.4 ± 29.8 ml, stage II: 55.9 ± 29.6 ml, stages I and II: 49.6 ± 29.8 ml, stage III: 56.0 ± 19.4 ml). DS, Durie–Salmon; tDV, total diffusion volume.
Fig 5.
Treatment effectiveness and apparent diffusion coefficient (ADC) values.
(A) Comparison between the responder (partial response or better, N = 13, ADCmode: 0.154 ± 0.386 ×10−3 mm2/s), stable (stable disease, N = 12, ADCmode: 0.038 ± 0.111 ×10−3 mm2/s), and non-responder (progressive disease, N = 13, ADCmode: -0.307 ± 0.424 ×10−3 mm2/s) groups. (B) Comparison between the responder (N = 13, ADCmode: 0.154 ± 0.386 ×10−3 mm2/s) and non-responder + stable (N = 25, ADCmode: -0.135 ± 0.351 ×10−3 mm2/s) groups. ΔADCmode was significantly higher in the responder group than that in the stable + non-responder group. (C) Average dFLC in the responder (-294.98 ± 677 mg/L), stable (-13.11± 25.11 mg/L) and non-responder (305.87 ± 715.10 mg/L) groups increased with a worsening in disease prognosis, albeit no significant difference was observed. (D) dFLC differed significantly between the responder (-294.98 ± 677 mg/L) and non-responder + stable (167.18 ± 552 mg/L) groups. dFLC, difference free-light chain; IMWG, International Myeloma Work Group.
Fig 6.
Proposed flowchart for treatment response assessment using DWIBS-MRI.
This proposed flowchart evaluates treatment effectiveness using MRI findings and ADC values. Patients considered “non-responders” should be candidates for treatment change. ADC, apparent diffusion coefficient; DWIBS, diffusion-weighted imaging with body signal suppression; MRI, magnetic resonance imaging.
Fig 7.
Proposed changes in bone marrow appearance and apparent diffusion coefficient (ADC) values according to pathology.
Normal bone marrow is low in water content due to its high fat cell content, resulting in a low ADC. In MGUS or early phase MM, the percentage of adipocytes in the bone marrow decreases, resulting in a relative increase in water content and, consequently, an increase in ADC values. In symptomatic MM, diffusion limitation owing to abnormal proliferation of neoplastic plasma cells in the bone marrow may result in a decline in ADC values. This diagram includes ADC values reported by Giles et al. [16] and in our study. ADC values for healthy adults were reported as average instead of mode, hindering a direct comparison; thus, we used dotted lines to differentiate these values. DS, Durie–Salmon; MGUS, monoclonal gammopathy of undetermined significance; MM, multiple myeloma.