Figure 1114

(A) Sagittal T1WI, (B) T2WI, and (C) postcontrast T1WI of a large chordoma. A very large tumor is demonstrated. The tumor has grown anteriorly into the pelvis from the lowermost edge of the sacrum, involving the coccyx and pushing the rectum forward. It is heterogeneous but mostly hypointense on T1WI (with some areas of increased signal) (A), and iso- to hyperintense on T2 with septations of low intensity. Following contrast administration it enhances and is easily depicted with fat suppression (C).

angiomas tend to occur in the lower thoracic spine. The more aggressive ones grow beyond the vertebral body boundaries and may compress the spinal cord or the exiting nerve roots. As they grow within the vertebral body they may compromise its structural integrity to the point of collapse. Patients with aggressive hemangiomas present with axial pain and tenderness. Only a minority develop slowly progressive radicular symptoms or myelopathic signs. Rarely, rapid-onset, progressive neurological compromise is seen. The symptoms may be caused by epidural expansion of the tumor, expansion of the vertebral body in response to tumor expansion, sudden bleeding, or vertebral body collapse.

Imaging Studies

Plain films reveal either parallel linear streaks or "honeycomb" appearance or vertical striation within the vertebrae (Figure 11-15). CT easily detects these lesions. The affected vertebra will show a "polka dot" appearance on axial cuts. Thickened trabeculae are surrounded with hypodense fatty tissue (Figure 11-16). Aggressive hemangiomas may extend beyond the vertebral body, penetrate into the spinal canal, and compress the spinal cord. In these cases MRI will better demonstrate the extent of soft tissue involvement. Benign hemangiomas usually appear hyperintense on both T1WI and T2WI (FSE) when there is a great amount of fatty tissue within the tumor. They may enhance

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