Percutaneous inoculated rabbit model of intervertebral disc space infection: magnetic resonance imaging features with pathological correlation.

OBJECTIVES: The aims of this study were to characterize MRI features in percutaneously inoculated spondylodiscitis rabbit models, to evaluate MRI for non-invasive diagnosis, and to assess the incremental information brought by the use of gadolinium-enhanced MR sequences. METHODS: Under fluoroscopic control, lumbar discs of 12 New Zealand White adult rabbits were injected with bacterial suspension. Five, 10 and 15 days after bacterial inoculation, T1 and T2 signal abnormalities and contrast enhancement of discs, vertebrae and epidural spaces were evaluated. Bacteriological and pathological analyses were realized after completion of imaging series. RESULTS: Disc space infections were present in all animals. MRI detected vertebral and discal abnormalities as soon as, respectively, 5 and 10 days after inoculation. Gadolinium-enhanced sequences allowed an earlier diagnosis, a more precise evaluation of the extent of the infection and the identification of epidural involvement. The signal of vertebrae was a more reliable criterion for infection evaluation that discal one. CONCLUSIONS: MRI is a reliable tool for non-invasive diagnosis of vertebral infection in a rabbit model and can be useful to compare the efficiency of different antimicrobial therapy in animal series before human administration. Gadolinium-enhanced MR sequences allow an earlier and more precise determination of the presence and extent of infection. Modifications of vertebral signal are the more reliable criterion for the evaluation of disc spaces infection.