Differentiation of intramedullary neoplasms and cysts by MR.

To determine the MR criteria that are effective for differentiating intramedullary neoplasms from syringo- or hydromyelia, we reviewed MR scans made on prototype and commercial imagers of 33 patients with surgically confirmed cord abnormalities, including nine intramedullary neoplasms and 20 cysts (syringo- or hydromyelia). Two radiologists who did not know the clinical and radiologic diagnoses were asked to evaluate the scans with respect to cord expansion, distinctness of the disease margin, homogeneity, and signal intensity. These observations were correlated with the proved diagnoses. The combination of distinct margins and uniform signal intensity equal to that of CSF correlated consistently (88%) with spinal cord cysts. Other combinations were less reliable for diagnosing a cyst or tumor.