MR and CT Imaging to Optimize CT-Guided Biopsies in Suspected Spondylodiscitis

The diagnostic value of computed tomography (CT)-guided spinal biopsy in patients with suspected spondylodiscitis is reported inconsistently in the literature. Our aim was to evaluate associations between procedural, clinical, and imaging parameters and the diagnostic yield of CT-guided spinal biopsy.

One hundred and two procedures performed in 87 patients with clinically suggested spondylodiscitis were analyzed retrospectively. Preprocedural magnetic resonance (MR) and CT images were evaluated regarding signal alterations, vertebral destruction, and soft-tissue involvement. The position of the biopsy needle in correlation with MR imaging findings was assessed. Patient characteristics and clinical details were noted. Parameters were compared in patients with positive and negative microbiological and histologic results.

Following microbiologic and histologic analysis, infectious spondylodiscitis was diagnosed in 29 and 23 biopsies, respectively. Microbiology results were significantly higher in biopsy specimens with central needle positioning within contrast enhancing tissue in correlation with the MR images (36% vs. 7%; P = 0.005). Biopsy specimens positioned in fluid-equivalent hyperintense discs in T2-weighted sequences yielded significantly lower microbiology results (6% vs. 33%; P = 0.036). Purely lytic endplate destruction and mixed vertebral density as shown by CT increased microbiology results (60% vs. 24%; P = 0.028). Previous antibiotic treatment for any cause did not influence microbiology yields significantly (P = 0.232).

MR imaging is mandatory to determine the optimal biopsy position. No clinical or imaging parameter could rule out a positive biopsy result and thus omit an unnecessary procedure. Biopsy should not be avoided if antibiotic treatment has previously been administered.