In vivo quantification of response to treatment in patients with multiple myeloma by 1H magnetic resonance spectroscopy of bone marrow

Magnetic resonance imaging (MRI) is the gold standard non-invasive technique to detect malignant disease in the bone marrow. Proton magnetic resonance spectroscopy (MRS) can be performed as a quick adjunct to routine spinal MRI. We performed proton MRS to patients with multiple myeloma (MM) at diagnosis and after treatment to investigate the possible correlation of MRS data with response to therapy. Twenty-one patients with newly diagnosed MM underwent combined MRI/MRS explorations of a transverse center section in the fifth lumbar vertebral body. MRS was acquired with STEAM and 40 ms TE. Areas of unsuppressed water and lipid resonances were used to calculate the lipid-to-water ratio (LWR). No association was detected between initial LWRs and the clinical characteristics of patients. Post treatment MRS was available in 16 patients of whom 11 (69%) presented an LWR increase, this included all complete responders (8/8, 100%, P = 0.012). A post-treatment LWR value equal to or larger than one is proposed as a non-invasive marker of complete response to treatment. Only patients responding to treatment presented a significant increase in bone marrow LWR after therapy. MRS may provide an adequate quantification of response to chemotherapy in patients with MM.