Role of Positron Emission Tomography/Computed Tomography in Bone Malignancies Patrick J. Peller, MD a,b, * INTRODUCTION Malignancies in the bone can arise from skeletal tissue itself (primary bone tumors), from a distant site (secondary or metastatic tumors), or from within the marrow space impinging primarily on the bone (multiple myeloma [MM]). Primary bone tumors are a heterogeneous group of sarcomas: osteosarcoma, Ewing sarcoma, chondrosarcoma, fibrosarcoma, and malignant fibrous histiocytoma. Their mesenchymal tissue of origin defines them. Bony metastases are the most common malignant bone tumor, and lung, breast, and prostate are the major primary cancer sites. 1 MM arises from a sin- gle clone of differentiated plasma cells, usually producing high levels of a monoclonal immuno- globulin. These malignant plasma cells proliferate within the marrow space and commonly produce osseous lesions. 2 Diagnostic imaging plays a critical role in the evaluation of patients with known or possible bone malignancies. Conventional anatomic imag- ing with plain film radiographs, ultrasonography, computed tomography (CT), and magnetic reso- nance (MR) imaging, and functional 99m Tc–methyl diphosphonate bone scintigraphy are established Disclosures: Dr Peller is a consultant for Eli Lilly and Company. a Nuclear Radiology, Mayo Clinic, 200 1st Street Southwest, Rochester, MN 55905, USA; b Department of Radi- ology, College of Medicine, Mayo Clinic, 200 1st Street Southwest, Rochester, MN 55905, USA * Department of Radiology, College of Medicine, Mayo Clinic, 200 1st Street Southwest, Rochester, MN 55905. E-mail address: peller.patrick@mayo.edu KEYWORDS  Fluorodeoxyglucose  Positron emission tomography  PET/CT  Osteosarcoma  Bony metastasis  Multiple myeloma KEY POINTS  Positron emission tomography combined with computed tomography (PET/CT) is useful in charac- terizing bone lesions that require biopsy.  PET/CT is and important adjunct in the staging of primary bone tumors, identifying favorable response to therapy and detecting recurrence.  In the evaluation of patients with common carcinomas, especially those arising from the lung, breast, and prostate, PET/CT is highly sensitive and specific for the detection of osseous metastases.  Multiple myeloma is a heterogeneous disease process exhibiting a wide range of biological behavior, which is reflected by the uptake of 18 F-labeled fluorodeoxyglucose (FDG) in skeletal and extraosseous lesions.  Some benign bone tumors are very metabolically active, and low-grade primary bone tumors demonstrate low FDG accumulation on PET/CT scans. Radiol Clin N Am 51 (2013) 845–864 http://dx.doi.org/10.1016/j.rcl.2013.05.005 0033-8389/13/$ – see front matter Ó 2013 Elsevier Inc. All rights reserved. radiologic.theclinics.com