Recently, MRI has been routinely used in detection and treatment of metastatic spine tumors, but no previous study on prediction and prevention of vertebral body collapse was done using MRI. This study was done to analyze the risk factors of collapse and to define criteria of impending collapse using MRI.

Ninety-five vertebrae of 69 patients with metastatic lesions were evaluated using ratio of involved axial area, sagittal area, costovertebral joint, pedicle, facet joint and uncovertebral joint involvement as independent variables. We defined collapse when there was a fracture of the end plate and loss of vertebral body height over 10%, and degree of collapse was measured as ratio of the body height to the mean of the height of adjacent bodies. The ratio of the involved area was measured on T1-weighted images which showed the largest area of tumor involvement.

There noted collapse of the bodies in 11 of 14 cervical vertebrae, 24 of 48 thoracic vertebrae and 15 of 33 lumbar vertebrae. Metastatic involvement on axial images was considered as a significant risk factor regardless of the vertebral level, while costovertebral joint destruction and axial involvement were significant risk factors in the thoracic spine. The criteria of impending collapse were: 51-60% axial involvement of the vertebral body in the cervical and lumbar spine; 61-70% axial involvement of the vertebral body with no destruction of other structures, 21-30% involvement of the vertebral body with destruction of one costovertebral joint or destruction of both costovertebral joints regardless of body involvement in thoracic spine.

Using the above criteria with consideration of the patient s general condition and biologic behavior of the primary tumor, prophylactic stabilization can be performed to prevent ver-tebral body collapse which results in severe pain or paralysis.