Whole-Body Imaging of Bone Marrow

For bone marrow screening, multimodality algorithms including conventional radiographs, bone scintigraphy, multislice computed tomography CT (MS-CT) scan, and dedicated magnetic resonance imaging (MRI) are widely established in clinical routine. Although radiographs are used as a basic imaging procedure for clarification of suspected focal bone pathologies, low sensitivity has been reported for the detection of limited osteolytic bone marrow destruction. Therefore, skeletal scintigraphy often is used as a more sensitive and integrated method in patients with suspected malignant bone marrow disease. MS-CT scan is the method of choice in the assessment of bone stability and allows for evaluation of fracture risk. Hybrid imaging concepts, such as positron emission tomography-computed tomography (PET-CT) scan, have been established as an effective tool for the detection of skeletal metastases, using the. additional metabolic information of a PET scan for the assessment of tumor viability and therapy response. MRI is an imaging technique that allows direct visualization of bone marrow components with high spatial resolution. The unique soft-tissue contrast of MRI enables precise assessment of bone marrow infiltration before osteolytic changes become visible in MS-CT or metabolic changes occur in bone scintigraphy or a PET scan. Furthermore it can depict tumor expansion into adjacent paraosseous structures, such as the spinal canal. The development of multichannel whole-body MRI (WB-MRI) systems has enabled bone marrow screening without use of ionizing radiation at high diagnostic accuracy. Parallel imaging techniques in combination with global matrix coil concepts, as well as the introduction of high-field whole-body scanners, have substantially reduced acquisition times without compromises in spatial resolution. WB-MRI has successfully been applied for screening of bone metastases and hematologic bone marrow diseases, like multiple myeloma, lymphoma, and histiocytosis X. Furthermore, it has recently been proposed for the assessment of primarily benign bone diseases predisposing for malignancy (e.g., multiple cartilaginous exostoses). This article provides an overview of state-of-art whole-body imaging of the bone marrow and highlights present and potential future applications, especially in the field of WB-MRI.