title: Pyogenic and non-pyogenic spinal infections: emphasis on diffusion-weighted imaging for the detection of abscesses and pus collections.
abstract: The incidence of spinal infections has increased in the past two decades, owing to the increasing number of elderly patients, immunocompromised conditions, spinal surgery and instrumentation, vascular access and intravenous drug use. Conventional MRI is the gold standard for diagnostic imaging; however, there are still a significant number of misdiagnosed cases. Diffusion-weighted imaging (DWI) with a b-value of 1000 and apparent diffusion coefficient (ADC) maps provide early and accurate detection of abscess and pus collection. Pyogenic infections are classified into four types of extension based on MRI and DWI findings: (1) epidural/paraspinal abscess with spondylodiscitis, (2) epidural/paraspinal abscess with facet joint infection, (3) epidural/paraspinal abscess without concomitant spondylodiscitis or facet joint infection and (4) intradural abscess (subdural abscess, purulent meningitis and spinal cord abscess). DWI easily detects abscesses and demonstrates the extension, multiplicity and remote disseminated infection. DWI is often a key image in the differential diagnosis. Important differential diagnoses include epidural, subdural or subarachnoid haemorrhage, cerebrospinal fluid leak, disc herniation, synovial cyst, granulation tissue, intra- or extradural tumour and post-surgical fluid collections. DWI and the ADC values are affected by susceptibility artefacts, incomplete fat suppression and volume-averaging artefacts. Recognition of artefacts is essential when interpreting DWI of spinal and paraspinal infections. DWI is not only useful for the diagnosis but also for the treatment planning of pyogenic and non-pyogenic spinal infections.
authors.affiliation: 1 Department of Radiology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: T
authors.initials: T
authors.lastname: Moritani
authors.forename: J
authors.initials: J
authors.lastname: Kim
authors.forename: A A
authors.initials: AA
authors.lastname: Capizzano
authors.forename: P
authors.initials: P
authors.lastname: Kirby
authors.forename: J
authors.initials: J
authors.lastname: Kademian
authors.forename: Y
authors.initials: Y
authors.lastname: Sato
mesh_terms: D000038:Abscess; D000368:Aged; D019299:Decompression, Surgical; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D015299:Discitis / Q000175:diagnosis*; D020802:Epidural Abscess / Q000175:diagnosis* / Q000601:surgery; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000175:diagnosis; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D013118:Spinal Cord Diseases / Q000175:diagnosis*; D013492:Suppuration / Q000175:diagnosis; D021801:Zygapophyseal Joint