Bone Marrow Microcirculation Parameter Amplitude A of Contrast-Enhanced Dynamic MRI Is a Prognostic Factor for Progressive Multiple Myeloma for Patients with Low Beta2-Microglobulin.

Introduction: We have previously shown that contrast-enhanced dynamic magnetic resonance imaging (dMRI) microcirculation parameters Amplitude A and distribution rate constant k_ep are significantly increased in patients with multiple myeloma (MM) compared to healthy controls and correlate with osteolytic bone involvement. Furthermore an elevated Amplitude A is associated with a high plasmacell-infiltration and increased microvessel density in bone marrow. We now evaluated the prognostic value of changes in microcirculation of bone marrow as detected by dMRI for overall (OAS) and event free survival (EFS) in patients with MM.

Methods: Between 1999 and 2001 62 patients with progressive MM requiring chemotherapy according to international standards (6 newly diagnosed patients, 56 patients with relapse or refractory disease) were investigated with dMRI of the lumbar spine. OAS and EFS were updated for all patients in February 2005. The estimated median follow up was 4.5 years. All patients underwent standardized dMRI with high temporal resolution (T1w-turboFLASH) before start of therapy. The contrast uptake was quantified using a two compartment model with the output parameters Amplitude A and distribution constant rate k_ep reflecting bone marrow microcirculation. To examine the prognostic value of the findings of dMRI we used the Proportional Hazards model as proposed by Cox.

Results: We recorded a correlation with borderline significance (p-value 0.1) between Amplitude A and EFS. We did not find a correlation of dMRI parameters with OAS. The multivariable analysis of Beta2-Microglobulin, age, Lactat Dehydrogenase (LDH) and Albumin revealed Beta2-Microglobulin as the only statistically significant prognostic factor for EFS in this group of patients. When patients were classified according to high or low Beta2-Microglobulin, Amplitude A was able to provide significant additional information characterizing EFS. Patients with low Beta2-Microglobulin and increased Amplitude A had significant shorter EFS than patients with low Beta2-Microglobulin and low Amplitude A.

Conclusion: Our investigations indicate that dMRI parameter Amplitude A which reflects the increased bone marrow microcirculation and angiogenesis is a novel prognostic factor for progressive multiple myeloma in patients with low Beta2-Microglobulin. So a more precise differentiation of patients may be possible through dMRI. The prognostic impact of dMRI for newly diagnosed myeloma patients and patients with monoclonal gammopathie with undetermined signifikance will now be evaluated in a prospective study.