Do metastases in vertebrae begin in the body or the pedicles? Imaging study in 45 patients.

We analyzed CT scans of the spine obtained in patients with vertebral metastases to determine what specific portion of the vertebra is initially involved by metastasis. The CT findings were then correlated with the abnormalities seen on plain films. Forty-five patients with histologically proved metastases in 95 vertebrae were included in the study. In all patients, CT scans and plain films of the spine were obtained within 1 week of each other. Analysis of the CT scans showed that the vertebral body was the portion of the vertebra that was most frequently destroyed by the metastases. Destruction of a pedicle was never identified in the absence of involvement of the body. The opposite was true on plain films, in which the most common finding was destruction of the pedicles. CT showed that the position of the metastases in the vertebra correlated with the sites of entry of the vertebral vessels. Our results show that the initial anatomic location of metastases within vertebrae is in the posterior portion of the body. Analysis of CT scans shows that the body is involved before the pedicles, although destruction of the pedicles is the most common finding on plain films. The pedicles are not the primary site of metastatic involvement. Destruction of the pedicles occurs only in combination with involvement of the vertebral body.