Learning Objectives: On successful completion of this activity, participants should be able to describe (1) the principle of combined labeled leukocyte/marrow imaging; (2) at least one advantage of 18 F-FDG PET or PET/CT over MRI for diagnosing spondylodiskitis; and (3) at least one advantage of SPECT/CT over planar imaging in the diagnosis of pedal osteomyelitis in diabetic patients.Financial Disclosure: The author of this article has indicated no relevant relationships that could be perceived as a real or apparent conflict of interest. CME Credit: SNMMI is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNMMI designates each JNM continuing education article for a maximum of 2.0 AMA PRA Category 1 Credits. Physicians should claim only credit commensurate with the extent of their participation in the activity. For CE credit, SAM, and other credit types, participants can access this activity through the SNMMI website (http://www.snmmilearningcenter.org) through September 2019.There are numerous imaging tests for diagnosing musculoskeletal infection. Radiographs are routinely performed, because even when not diagnostic, they provide an anatomic overview of the region of interest that could influence subsequent procedure selection and interpretation. MRI is sensitive and provides superb anatomic detail. Bone scintigraphy accurately diagnoses osteomyelitis in bones not affected by underlying conditions. 67 Ga is used primarily for spondylodiskitis. Although in vitro labeled leukocyte imaging is the radionuclide test of choice for complicating osteomyelitis such as diabetic pedal osteomyelitis and prosthetic joint infection, it is not useful for spondylodiskitis. Antigranulocyte antibodies and antibody fragments have limitations and are not widely available. 111 In-biotin is useful for spondylodiskitis. Radiolabeled synthetic fragments of the antimicrobial peptide ubiquicidin are promising infection-specific agents. 18 F-FDG is the radiopharmaceutical of choice for spondylodiskitis. Its role in diabetic pedal osteomyelitis and prosthetic joint infection is not established. Preliminary data suggest 68 Ga may be useful in musculoskeletal infection. 124 I-fialuridine initially showed promise as an infection-specific radiopharmaceutical, but subsequent investigations were disappointing. The development of PET/CT and SPECT/CT imaging systems, which combine anatomic and functional imaging, has revolutionized diagnostic imaging. These hybrid systems are redefining the diagnostic workup of patients with suspected or known infection and inflammation by improving diagnostic accuracy and influencing patient management.