MULTIPLE MYLOMA

Multiple Myloma

Multiple Myloma

Abstract

For the correct staging of patients with multiple myeloma sensitive detection is mandatory in order to estimate prognosis and to decide for adequate therapy. Magnetic resonance imaging (MRI) is superior to radiography for both, focal and diffuse involvement. Five different infiltration patterns can be differentiated: (1) normal appearance of bone marrow despite minor microscopic plasma cell infiltration, (2) focal involvement, (3) homogeneous diffuse infiltration, (4) combined diffuse and focal infiltration, (5) “salt-and-pepper”-pattern with inhomogeneous bone marrow with interposition of fat islands. For the fast and complete assessment of all patterns a combination of a T1-weighted spin echo sequence and a fat suppression technique should be employed. The focal involvement is clearly demonstrated as areas of high signal intensity on, e.g. STIR images. Diffuse involvement is best detected on unenhanced T1-weighted SE sequences and it manifests as homogeneous signal reduction. It can be quantified objectively by calculation of the percentage of signal intensity increase after contrast material injection. With parallel imaging and special coil devices, such as total imaging matrix (Siemens systems, Avanto) a “screening” of the whole red bone marrow as for myeloma infiltration is possible within a reasonable time. Patients without bone marrow infiltration have a significantly longer survival than patients with bone marrow infiltration in MRI at the time of diagnosis. However, even in stage I disease (Durie and Salmon) and negative X-ray films bone marrow infiltration in MRI may be detected in 29-50% of patients. Those patients typically show an earlier disease progression. Recently, MRI has been implemented in the clinical staging of patients with multiple myeloma. MRI may also monitor response to therapy. Signs of good response in cases with focal involvement are: reduction of signal intensity on T2-weighted spin echo images, lack or rim-like enhancement after contrast material injection or even a normalisation of bone marrow signal. In case of diffuse involvement a partly patchy reconversion to fatty marrow can be seen.

Table of Contents

Abstract2

1. Introduction5

2. Pattern of infiltration and choice of sequences6

3. Comparison of radiography and MRI11

4. MRI versus MSCT14

5. Prognostic significance of MRI16

6. Monitoring under therapy22

7. Conclusion24

References26

1. Introduction

In the last decades Magnetic Resonance imaging (MRI) has become an indispensable tool for clinical diagnostics due to its non-invasive character, lack of exposure to radiation and to its unique capability to differentiate soft-tissues. MRI offers a direct, high-contrast and sensitive visualization of bone marrow [1]. By the use of MRI it is possible to detect metastases more sensitively compared to conventional X-ray and to skeletal and bone marrow scintigraphy [2] and [3].

Multiple myeloma represents a malignant bone marrow neoplasia in which a monoclonal strain of atypical plasma cells proliferate and secrete typically paraproteins detected in electrophoresis. These atypical plasma cells are distributed in the bone marrow either focally or in a diffuse manner and they may result in bone destruction. Bone marrow biopsy or bone marrow aspirate are essential for the diagnosis. A patient is diagnosed as having multiple myeloma in case of >10% atypical plasma cells found in the extracted aspirated ...