Clinical
Presentation: A 58-year-old male with a history of discitis. Status post-surgery, there is now concern for osteomyelitis and abscess formation.
Imaging Findings: Osteomyelitis with abscess formation.
Figures 1-3: There is a large area of abnormal signal intensity in the L1-2 intervertebral discs and adjacent opposing end plates, which shows marginal enhancement. The superior part of the L1 body and inferior part of L2 show diffuse enhancement (Fig. 3 arrow). Discitis and osteomyelitis are suspected. The abnormal area also extends into the paravertebral soft tissue component with formation of bilateral psoas collections, which has inhomogeneous and intermediate contrast.
Abscess formation is suspected. The L5 vertebral body has a hemangioma, which is an incidental finding.
Diagnosis: Osteomyelitis with abscess formation
Discussion: The operation was performed. The operative finding was subacute osteomyelitis with psoas abscess formation and then antibiotic therapy was given for eight weeks. Vertebral osteomyelitis accounts for 1% of skeletal infections. Staphylococcus aureus is the most common isolated organism. The clinical picture is nonspecific. Back pain is by far the most common presenting symptom. Notably, fever can be absent at presentation, thus distracting the clinician from the possibility of infection and delaying the diagnosis.
Therefore, an imaging diagnosis has an important role to detect the infectious process earlier these days. The literature evaluating MR findings used by radiologists demonstrates that criteria with a low sensitivity and limited clinical use include hypointensity of the disk on T1-weighted MR images and decreased height of intravertebral space. Criteria with good to excellent sensitivity include evidence of either paraspinal or epidural inflammatory tissue, contrast enhancement of the disk, hyperintensity of fluid equivalent signal intensity on T2-weighted MR images and erosion or destruction of the vertebral endplates on T1-weighted MR images. Spinal infection may rarely involve only one vertebral body and the adjacent disk, or exclusively the epidural space. Pyogenic hematogenous infections frequently involve several spinal levels.
References:
Mylona E, Samarkos M, Kakalou E, Fanourgiakis P, Skoutelis A. Pyogenic vertebral osteomyelitis: a systematic review of clinical characteristics. Semin Arthritis Rheum. 2009 Aug;39(1):10-7. PMID: 18550153 [PubMed]
