Vertebral infection

Vertebral infection represents 2-4% of all cases of osteomyelitis. An increase in the incidence of pyogenic as well as granulomatous spondylitis has been noticed. Early radiological diagnosis is of great importance for prompt treatment and prevention of clinically significant consequences which include neural compromise and late spinal deformities. The most frequent causative pyogenic micro-organisms are gram-negative bacteria especially Staphylococcus aureus. An important form of nonpyogenic granulomatous infection is tuberculous spondylitis which represents the most common form of extrapulmonary tuberculosis. The routes of spinal infection include hematogenous spread, postoperative infections, direct implantation during spinal punctures and spread from a contiguous focus. The role of imaging is an early diagnosis, evaluation of extent of infection with special regard to potential neural compromise, differential diagnosis, guidance of diagnostic biopsy, planning of eventual operative procedures and assessment of therapeutic response. Imaging modalities include bone scintigraphy, radiography, CT and MRI. In practice, usually a combination of a sensitive and a specific method is utilised. The only imaging modality which combines high sensitivity with satisfactory specificity is MRI. This is the reason that MRI frequently has become the first imaging modality in clinically suspect spinal infection. The MRI is the method of choice for direct demonstration of extension of infection, especially of eventual epidural abscess or phlegmon and consecutive neural compression. Using MRI monitoring of therapeutic efficiency is possible.