 Introduction/Background Spine infection is a disease that occurs when either microorganisms or viruses invade and involve one or more structures within or surrounding the spine [1-7]. Although uncommon, the incidence of spine infection appears to be increasing because of a combination of predisposing factors, such as an increasing number of susceptible hosts, an increase in the number of interventional and surgical spine procedures, and an increase in diagnostic testing [5,8- 11]. Potential host factors include preexisting extraspinal infection (endocarditis, HIV, pulmonary infection), intravenous (IV) drug use, diabetes mellitus, hepatic or renal failure, rheumatologic disease, or immunosuppression [12,13]. Spine infection presents a diagnostic and management challenge [14]. Diagnostic delay is not uncommon because of an often indolent clinical presentation with nonspecific presenting signs and symptoms such as back pain, fever, and, less commonly, neurologic compromise [3,8,10]. The location of the spine infection is also important because it may influence the clinical presentation and the subsequent imaging evaluation. One or more spine structures and/or compartments may be infected, and this also influences the imaging findings [1,14]. Spine infection is often extradural, initially invading the vertebral endplate in adults via a hematogenous route and centering about the vertebral endplate (osteomyelitis) and intervertebral disc (discitis). Spine infection may also arise initially within a facet joint. Spine infection occurs less frequently in children and initially affects the intervertebral disc [15]. Epidural and paraspinal soft tissue involvement are not uncommon [16,17]. Other important clinical manifestations of spine infection with imaging and management implications include epidural (abscess), subarachnoid (meningitis) space involvement, or spinal cord involvement (myelitis) [18,19].
Suspected Spine Infection PCAs.  Introduction/Background Spine infection is a disease that occurs when either microorganisms or viruses invade and involve one or more structures within or surrounding the spine [1-7]. Although uncommon, the incidence of spine infection appears to be increasing because of a combination of predisposing factors, such as an increasing number of susceptible hosts, an increase in the number of interventional and surgical spine procedures, and an increase in diagnostic testing [5,8- 11]. Potential host factors include preexisting extraspinal infection (endocarditis, HIV, pulmonary infection), intravenous (IV) drug use, diabetes mellitus, hepatic or renal failure, rheumatologic disease, or immunosuppression [12,13]. Spine infection presents a diagnostic and management challenge [14]. Diagnostic delay is not uncommon because of an often indolent clinical presentation with nonspecific presenting signs and symptoms such as back pain, fever, and, less commonly, neurologic compromise [3,8,10]. The location of the spine infection is also important because it may influence the clinical presentation and the subsequent imaging evaluation. One or more spine structures and/or compartments may be infected, and this also influences the imaging findings [1,14]. Spine infection is often extradural, initially invading the vertebral endplate in adults via a hematogenous route and centering about the vertebral endplate (osteomyelitis) and intervertebral disc (discitis). Spine infection may also arise initially within a facet joint. Spine infection occurs less frequently in children and initially affects the intervertebral disc [15]. Epidural and paraspinal soft tissue involvement are not uncommon [16,17]. Other important clinical manifestations of spine infection with imaging and management implications include epidural (abscess), subarachnoid (meningitis) space involvement, or spinal cord involvement (myelitis) [18,19].