David Nathan Sandman MD, Presenter: Nothing to Disclose

Glenn A. Tung MD, Abstract Co-Author: Nothing to Disclose

Although there are imaging signs of advanced discitis, osteomyelitis, and spinal epidural abscess (SEA), signs of early infectious spondylitis are less well known. The purpose of this study is to describe imaging signs of early infectious spondylitis that were unrecognized on imaging tests performed prior to diagnostic spinal MR imaging.

Retrospective search was performed for MR imaging (“reference study”, RS) performed between 1/05 and 11/07 on which the diagnosis of discitis, vertebral osteomyelitis, or epidural abscess was made. A search for antecedent imaging studies (“index study”, IS) performed within 2 months of the RS in which these diagnoses were not mentioned was performed. The IS was compared to the RS for signs of early spondylitis and the technical quality of the IS was evaluated. SEA progression between IS and RS was quantified and correlated with antimicrobial therapy.

Twelve index studies (spine MRI, n=9; abdomen CT, n=2; spine CT, n=1) were identified from 60 reference studies. The 12 IS-RS pairs were performed on 8 men and 3 women of mean age 58.4 years. The average time between IS and RS was 17.1 days (range, 1-51). Early signs of SEA on MRI include mildly thickened (n=2) or enhancing epidural fat (n=1), abnormal signal in the disc and endplate extending into paraspinal fat (n=1), and small epidural fluid collection with cord distortion (n=1). Early signs on CT are increased density in the paravertebral space without (n=2) or with (n=1) endplate irregularity and thecal sac displacement (n=3). Technical errors include incomplete study due to discomfort (n=1) and inadvertent omission of integral pulse sequences (n=3). While antimicrobial therapy was not administered between the IS and RS in two cases with the largest SEA, average growth per day did not correlate with antimicrobial administration but may be due to small sample size. 

Diagnosis of infectious spondylitis can be expedited by recognition of early and secondary signs on MRI, attending the spinal canal on CT studies, and avoidance of technical errors. More data is needed for evaluation of SEA growth rate in relation to antimicrobial therapy.

Infectious spondylitis can be diagnosed with increased frequency on initial imaging evaluation by recognizing early or secondary signs and limiting technical errors.

Sandman, D, Tung, G, Early Signs of Infectious Spondylitis on CT and MR Imaging.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6008860.html