MRI appearance of spinal lesions: metastatic tumors or infections?

Three patients with pathologically verified spinal osteomyelitis and another three with metastatic tumors of the spine were investigated. MRI of th spine of four patients showed several unusual findings. The preservation of intervertebral discs and endplates did not predict accurately the diagnosis of either infections or tumors. The "pepper and salt" appearing feature may also occur in a metastatic tumor. Plain radiographs, CT, and radioisotope bone scans were less sensitive than MRI to disclose the lesions. In cases of osteomyelitis, the systemic sources of infections were frequently not found, and the responsible microorganisms could not be identified even from the surgical specimens of two patients. However, mycobacterium tuberculosis was found in the surgical specimen of a patient with cervical spinal lesion whose MRI was indistinguishable from a metastatic tumor. Surgicopathological diagnosis was therefore crucial and mandatory in these instances.