In Reply.—
We appreciate Dr Jahnke's comments reiterating some important points that we made in our article, namely, that metrizamide CT cisternography is an excellent imaging modality for diagnosing the empty sella syndrome, using a relatively low dose of metrizamide. However, high-quality CT cisternograms are not always obtainable owing to a variety of factors, including technical problems with the scanner, artifacts, and positioning difficulties.Our experience and that of others at large centers have shown that polytomography immediately following the intrathecal instillation of metrizamide is a complementary adjunct to CT cisternography and, occasionally, may be the only imaging modality available to the neuroradiologist once the subarachnoid space has been invaded.Techniques employing higher concentrations of metrizamide or special positioning of the patient during instillation of metrizamide via lumbar puncture have been described, yielding excellent images with polytomography.1,2 Structural changes in the spinal canal, such as osteophytes, canal stenosis, and