MRI Features Associated With the Detection of Microbial Pathogens by CT-Guided Biopsy in Septic Spondylodiscitis.

ABSTRACT

OBJECTIVE: The aim of this study was to assess the magnetic resonance imaging (MRI) features associated with microbial pathogen detection by computed tomography (CT)-guided biopsy in patients with suspected septic spondylodiscitis. METHODS: For the last 10-year period, we analyzed the medical records of patients who underwent MRI and CT-guided biopsy for suspected septic spondylodiscitis. Clinical characteristics were recorded. The following MRI features were assessed edema or contrast enhancement of the intervertebral disc, adjacent vertebrae, epidural and paravertebral space, presence of abscess, and paravertebral edema size. A positive biopsy was defined by pathogen identification on bacterial analysis or the presence of granuloma on histology. Predictors of a positive biopsy were assessed with a logistic regression model. RESULTS: We examined data for 61 patients (34 [56%] male; mean age, 59.9 ± 18.0 years); for 35 patients (57%), CT-guided biopsy was positive for a pathogen. The 4 MRI findings significantly associated with a positive biopsy were epiduritis, greater than 50% vertebral endplate edema, loss of intradiscal cleft, and abscess. The size of paravertebral edema was greater with a positive than negative biopsy (median, 15.9 [interquartile range, 11.3-21.3] vs 7.3 [4.6-12.9] mm; p = 0.004). On multivariable analysis, epiduritis was the only independent predictor of a positive biopsy (adjusted odds ratio, 7.4 [95% confidence interval, 1.7-31.4]; p = 0.006). CONCLUSIONS: Epiduritis and the size of paravertebral edema on MRI are associated with detection of a microbial pathogen in suspected septic spondylodiscitis. For patients without these MRI signs, the need for further investigations such as enriched or prolonged cultures, a second CT-guided biopsy, or even surgical biopsy need to be discussed.