Neovascularization of bone marrow in patients with diffuse multiple myeloma - A correlative study of magnetic resonance imaging and histopathologic findings

BACKGROUND. The goal of the current study was to assess the correlation between bone marrow histology and contrast enhancement in infiltrative diffuse myeloma. METHODS. Forty-four patients with homogeneous diffuse infiltration of bone marrow by multiple myeloma were examined using magnetic resonance imaging of the spine. The sequence protocol included T1-weighted spin-echo (pre- and post-gadolinium dimeglumine administration) and short-inversion time inversion recovery sequences. The percent increase in signal after intravenous gadolinium administration was calculated in bone marrow from patients with myeloma and from a control group of 86 patients who did not have bone marrow disease. Grade of infiltration with plasma cells, fat cell content, and hematopoietic marrow content were evaluated via histologic assessment of bone marrow, and microvessel density was evaluated via anti-CD34-positive immunostaining. RESULTS. increased microvessel density was observed in association with increasing plasma cell content (Kruskall-Wallis test: P < 0.0001). Contrast enhancement increased in a stepwise manner according to grade of microvessel density (Mann-Whitney U test: P < 0.05 and P < 0.001 for increases from low to intermediate and intermediate to high grade) and was significantly higher in patients with myeloma compared with control patients (Mann-Whitney U test: P < 0.001). A significant correlation also was found between histologic extent of tumor infiltration and contrast enhancement (Mann-Whitney U test: P < 0.0001). The mean level of contrast enhancement was 18% in the control group, 26% in patients with lowgrade infiltration, 49% in patients with intermediate-grade infiltration, and 90% in patients with high-grade infiltration. In addition, fat cell content was found to be inversely correlated with contrast enhancement (chi-square test: P < 0.01). CONCLUSIONS. As a consequence of increased microvessel density, decreased fat cell content, and increased cellularity, the presence of diffuse bone marrow infiltration in patients with multiple myeloma can be verified using gadolinium-enhanced magnetic resonance imaging. (C) 2004 American Cancer Society.