Spondylodiscitis. Clinical and magnetic resonance diagnosis.

STUDY DESIGN: This study reviews 65 patients with spondylodiscitis, both spontaneous and postoperative and of different etiology, studied by magnetic resonance imaging.

OBJECTIVES: To define the magnetic resonance imaging characteristics of infections of the spine in acute and chronic stages and to evaluate the role of magnetic resonance imaging in defining their etiology.

BACKGROUND DATA: Early diagnosis of spondylodiscitis is often difficult because of the long latent period. Radiographs of the spine, bone scan, and computed tomography scan provide insufficient data.

METHODS: Among 65 patients with spondylodiscitis studied by magnetic resonance imaging, 24 were examined in the acute stage (clinical evolution between 7 days and 20 days), and 41 were examined in the chronic stage (3-6 weeks). The etiologic agent was staphylococcus in eight cases, Brucella in 13, Mycobacterium tuberculosis in 29, Salmonella in four, and unknown in 11.

RESULTS: In cases observed in the acute stage, the disc and the vertebral bodies were hypointense in T1 and hyperintense in T2; this relatively constant finding was not correlated with the etiologic agent. In the chronic stage, cases caused by Brucella or of unknown etiology showed long T1 and T2 relaxation times, with precocious contrast enhancement of the disc; in cases of tubercular etiology there was slight shortening of T1, with inhomogeneous enhancement of the involved vertebral bodies and late disc enhancement.

CONCLUSIONS: Magnetic resonance imaging is the investigation method of choice in diagnosing spondylodiscitis, especially in very early stages of the disorder, when other investigations still yield negative results. In chronic stages, magnetic resonance imaging also allows tubercular spondylodiscitis to be distinguished from cases of different etiology.