Differentiation Between Brucellar and Tuberculous Spondylodiscitis in the Acute and Subacute Stages by MRI: A Retrospective Observational Study.

RATIONALE AND OBJECTIVES: The aim of this study was to reveal the distinctive features of magnetic resonance imaging (MRI) for distinguishing brucellar spondylodiscitis (BSD) from tuberculous spondylodiscitis (TSD) in the acute and subacute stages.

METHODS: This study involved 14 patients with BSD and 18 patients with TSD from May 2011 to January 2015. BSD was diagnosed based on ≥1/160 titers of a Brucella agglutination test or isolation of Brucella spp. TSD was diagnosed based on the isolation of tuberculosis bacteria. All patients underwent T1- and T2-weight imaging (T1WI and T2WI) and fat suppression T2WI (FS T2WI). The height and the signal intensity (SI) of the vertebra and intervertebral disc were assessed. The distinctive MRI features were compared using the chi-square test. The SI of the vertebra between BSD and TSD was observed in terms of histogram characteristics of kurtosis, skewness, and percentile (75%-25%) on FS T2WI.

RESULTS: Twenty-nine (76.3%) vertebrae of BSD were infected throughout the whole vertebra, and 49 (90.7%) vertebrae of TSD were infected near the osseous end plate (P <.001). Compared to TSD, the vertebral height of BSD was nearly intact (P <.001), owing to the new bone formation in the end plate without vertebral collapse. Furthermore, significant differences in the SI of the vertebra were observed between patients with BSD and TSD in terms of homogeneous characteristics on FS T2WI, that is, kurtosis (BSD vs TSD, 0.107 vs -0.250, P = .023), skewness (BSD vs TSD, -0.021 vs 0.266, P = .017), and percentile (75%-25%) (BSD vs TSD, 54.498 vs 79.399, P = .00049).

CONCLUSIONS: The nearly intact vertebra with homogeneous high signal on FS T2WI was an important MRI feature for distinguishing BSD from TSD in the acute and subacute stages.