Benign vertebral lesions are usually asymptomatic and incidentally detected (Table 11.1), while malignant tumors cause back pain and sometimes manifest neurologic symptoms (Table 11.2). Initial imaging is usually plain radiography, which is not sensitive unlike in appendicular bones because of the complex anatomy of the vertebrae. Plain radiography, however, helps the surgeon in making a decision regarding overall spinal balance and the need for stabilization. CT is useful in the evaluation of bone destruction and calcified tumor matrix. CT helps evaluate the risk for vertebral body collapse. MR imaging is the best imaging modality for the evaluation of the epidural space and neural structures. T1-weighted MR images can delineate bone marrow architecture and fat content within masses. Postcontrast study is helpful to depict soft tissue vascularity and to differentiate cystic lesions from solid masses. Conventional angiography is invasive and usually used for preoperative embolization of the spinal tumors. Angiography is useful in determining the precise relationship between the tumor and the spinal vessels, especially in the evaluation of the artery of Adamkiewicz in the thoracolumbar region.

Cervical spinal tumors should be evaluated to describe their relationship to the vertebral arteries. In thoracic spinal tumors, it is necessary to depict the relationship to the ribs, posterior mediastinum, and pleura. Lumbar spinal tumors may involve the retroperitoneum. Sacral tumors can extend to the sacroiliac joints.

The differential diagnosis of spinal tumors can be narrowed down by evaluating the imaging findings including morphology or signal intensity of lesions, as well as enhancement patterns. Besides imaging findings, the age of the patient, number of the lesions, and location in the spine are most important in the differential diagnosis.

Intradural extramedullary tumors are mainly composed of nerve sheath tumors and meningiomas (Table 11.6). Nerve sheath tumors are the most common intraspinal tumors and have two histologic types, schwannoma and neurofibroma. Most intraspinal nerve sheath tumor is solitary schwannoma, whereas neurofibroma can be multiple and usually associated with neurofibromatosis type I. Nerve sheath tumors are well-defined, solid masses of intermediate signal intensity on T1-weighted images. On T2-weighted images, they have variable signal intensity, sometimes a target appearance. Enhancement is variable and can be strong and homogeneous in most cases. Neurofibromas tend to encase the nerve roots and schwannomas which displace the nerve root due to their asymmetric growth. Schwannomas commonly have hemorrhage and cyst formation, which are rare in neurofibromas. When the tumor is solitary, however, differentiation of schwannoma and neurofibroma on MR imaging is very difficult.

Meningiomas of the spine often have calcifications. Most of meningiomas have similar signal intensity to the spinal cord on T1- and T2-weighted images. Meningiomas enhance strongly and homogeneously after administration of contrast agent and the attached dura to the masses can be enhanced (dural tail sign) (De Verdelhan et al. 2005).