Role of Standard Magnetic Resonance Imaging

Bone disease is a clinical hallmark of multiple myeloma (MM), occurring in almost all patients during the course of the disease. It represents one of the main causes of morbidity and mortality in affected patients and can justify on its own the initiation of treatment in presence of a biopsy-proven medullary or extramedullary plasmacytoma. Over the past few years, modern imaging techniques have gained increasing importance in the management of MM. Currently, cross-sectional imaging is incorporated in the definition of myeloma-related bone disease deserving of treatment and is required for a correct staging as well as for treatment-response evaluation. Magnetic resonance imaging (MRI) allows to directly visualize bone marrow infiltration much earlier than myeloma-related bone destruction and it is considered the imaging gold-standard method for the detection of myeloma bone marrow involvement. MRI is the procedure of choice to evaluate painful lesions and discriminating between benign from malignant vertebral fractures and it has also the ability to localize spinal cord and/or nerve root compression for surgical intervention or radiation therapy. Moreover, whole-body MRI is currently included in the diagnostic work-up of otherwise considered asymptomatic myeloma and solitary bone plasmacytoma, with remarkable therapeutic implications. However, despite its added value in the initial disease assessment, conventional MRI is of limited value in the evaluation of response after treatment since it only provides morphological information. This chapter will give a comprehensive overview of the role of conventional MRI in diagnostic and post-treatment evaluation of patients with myeloma, underlining its strengths and weaknesses at various time points of the disease. Exhaustive acquisition protocols for an adequate evaluation of bone marrow disease involvement will be discussed in the light of currently accepted standards and the most important MR imaging findings will be illustrated alongside their prognostic value. Understanding the advantages and limitations of conventional MRI and its complementary value in staging and disease monitoring compared to other imaging techniques is essential to optimize patients’ management, especially in the new era of novel treatment approaches that have significantly improved rates and depth of response