Preoperative estimation of metastatic vertebral tumors

Total en bloc spondylectomy was performed in 22 patients with metastatic vertebral tumors. Osteolytic lesions were present in 15 cases while 7 cases had osteoblastic or mixed lesions. We measured the dimensions of the tumors preoperatively using magnetic resonance imaging (MRI) and computerized tomography (CT), and postoperatively by histological examination of the resected specimens. In the osteolytic group, the dorsoventral and transverse diameters of the metastatic tumor as measured on MRI were significantly greater compared to those determined by the histological examination. On the other hand, the same parameters measured by CT were smaller than the histologically determined dimensions. Although there were no significant differences between measurements of osteoblastic and osteolytic tumors, CT underestimated dimensions in osteoblastic or mixed tumors more than in those of osteolytic tumors. Estimation of tumor dimensions and local invasion using MRI and CT should be interpreted carefully.