Dynamic contrast-enhanced MRI for assessing the disease activity of multiple myeloma:: A comparative study with histology and clinical markers

Purpose: To examine whether parameters of dynamic, contrast-enhanced MRI (DCE MRI) reflect the degree of infiltration and vessel density in corresponding bone marrow biopsy specimens. Materials and Methods: The pelvis of 24 patients with multiple myeloma (MM) was examined using contrast-enhanced DCE MRI. Biopsy was obtained from the spina iliaca posterior superior. Using a two-compartment model (assuming one intravascular and one interstitial compartment), the parameters amplitude (A, the maximum, relative signal increase over baseline) and the exchange rate constant (k(ep) describing the redistribution of contrast agent from the interstitial into the intravascular compartment) in the biopsied region were calculated and compared with the histological and clinical data. Results: DCE MRI parameters were significantly higher in lesions with marked infiltration than with mild or no infiltration (P < 0.05). The amplitude normalized to that in the iliac artery (A(n)), but not k(ep), was higher in lesions with high vessel-density at histology (P = 0.01). Higher k(ep) levels were found in presence of increased serum immunoglobulins. Conclusion: Increased contrast uptake in the bone marrow of MM patients indicates at least moderate tumor involvement. Furthermore, the contrast enhancement correlates with vessel-density and serum markers of disease activity.