title: Diffusion-weighted MRI "claw sign" improves differentiation of infectious from degenerative modic type 1 signal changes of the spine.
abstract: OBJECTIVE
  Modic type 1 degenerative signal changes can mimic/suggest infection, leading to additional costly and sometimes invasive investigations. This retrospective study analyzes the utility and accuracy of a novel, diffusion-weighted "claw sign" for distinguishing symptomatic type 1 degeneration from vertebral diskitis/osteomyelitis.
  
  
  METHODS
  Seventy-three patients with imaging features resembling type 1 degeneration were classified clinically into 3 groups: true degenerative type 1 changes (n = 33), confirmed diskitis/osteomyelitis (n = 20), and radiologically suspected infection later disproved clinically (n = 20). A claw sign was defined on DWI as well-marginated, linear, regions of high signal situated within the adjacent vertebral bodies at the interface of normal with abnormal marrow. Two blinded neuroradiologists independently rated the presence of the claw sign, along with T2 disk signal and disk and endplate enhancement to determine the utility of each for identifying degeneration versus infection.
  
  
  RESULTS
  When the 2 neuroradiologists identified a definite claw, 38 of 39 patients (97%) and 29 of 29 patients (100%) proved to be infection-free. When the readers identified a probable claw, 14 of 14 patients (100%) and 16 of 19 patients (84%) proved to be infection-free. Conversely, when the readers identified the absence of claw sign (diffuse DWI pattern), there was proved infection in 17 of 17 cases (100%) and 13 of 14 cases (93%).
  
  
  CONCLUSIONS
  In patients with type 1 signal changes of the vertebral disk space, a claw sign is highly suggestive of degeneration and its absence strongly suggests diskitis/osteomyelitis.
authors.affiliation: From the Department of Neuroradiology, Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: K B
authors.initials: KB
authors.lastname: Patel
authors.affiliation: From the Department of Neuroradiology, Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: M M
authors.initials: MM
authors.lastname: Poplawski
authors.affiliation: From the Department of Neuroradiology, Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: P S
authors.initials: PS
authors.lastname: Pawha
authors.affiliation: From the Department of Neuroradiology, Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: T P
authors.initials: TP
authors.lastname: Naidich
authors.affiliation: From the Department of Neuroradiology, Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York. lawrence.tanenbaum@mountsinai.org.
authors.forename: L N
authors.initials: LN
authors.lastname: Tanenbaum
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D015299:Discitis / Q000175:diagnosis*; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000175:diagnosis*; D008159:Lumbar Vertebrae; D008297:Male; D008875:Middle Aged; D010019:Osteomyelitis / Q000175:diagnosis*; D012189:Retrospective Studies
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