MRI and operative findings of spinal intramedullary tumors

The MRI findings of spinal intramedullary tumors are not yet established, so we tried to study these tumors, especially astrocytomas and ependymomas, which are the most common intramedullary spinal cord tumors, and to speculate how completely we could remove them. Astrocytomas were isointense on T1-weighted images and high-intense on T2-weighted images, and they were heterogeneously enhanced by Gd-DTPA. During the operation, the boundaries of the tumors were not clear, so they could not be totally removed. Ependymomas which were situated above the conus medullaris were isointense and high-intense on T1- and T2-weighted images respectively. The associated cysts were low- and high-intense on T1-and T2-weighted images respectively. Tumors were enhanced homogeneously by Gd-DTPA and were well-circumscribed, so the majority of the tumors could be removed totally. Ependymomas below the conus medullaris extended in the extramedullary direction from the bottom of the conus and developed downward, involving the cauda equina in 3 cases of the 4, 2 cases of which were myxopapillary ependymomas. On MRI they were isointense on the T1-weighted images, but on the T2-weighted images they were high-intense, including a low-intensity area which showed necrosis or a hemosiderin deposit of an old hemorrhage. Moreover they were enhanced by Gd-DTPA, remaining low-intense on the T2-weighted images. Since these tumors adhered tightly to the cauda equina, they could not be removed totally. (author)