[Study of vertebral metastasis by MR imaging: significance of T2*weighted image (gradient field echo) and metastatic pattern].

Fifty-one patients with vertebral metastasis were studied by MR imaging. T1 and T2*-gradient field echo (FE) sequences (0.5 Tesla) were performed in all patients. Primary sites were the lung (10 cases), breast (9 cases), colorectal area (9 cases), prostate (7 cases), liver (4 cases) and others. Of the 618 vertebrae evaluated, 315 had metastatic abnormalities, 241 (76.5%) of which showed low intensity on T1-weighted images. High intensity lesions on T2* weighted images were seen in 301 vertebrae (95.5%). Concerning the distribution of metastatic lesions, lumbosacral vertebrae were the most common sites, with the thoracic spine second in frequency. No significant difference was noticed between these primary sites. A total of 244 metastatic lesions occupied most of the vertebral body, 49 of which were accompanied with epidural tumors. Seventy-one small lesions were considered early metastasis, two-thirds of which were located in the metaphysis of vertebrae. No epidural tumors were seen in this group. These findings suggest that the main route for metastatic cancer cells to the vertebrae is the systemic circulation rather than the vertebral venous system.