Intracranial delivery of metrizamide from the lumbar subarachnoid space: prone versus supine positioning.

Forty patients undergoing metrizamide computed tomographic cisternography (MCTC) were prospectively evaluated for the relative merits of prone and supine positioning for the intracranial delivery of the subarachnoid contrast material. Twenty patients were prone and 20 supine when tilted head downward. The degree of opacification was deemed satisfactory or unsatisfactory in each case for the various ventricles and for the suprasellar, quadrigeminal, perimesencephalic, and cerebellopontine angle cisterns. The visualization of the suprasellar and perimesencephalic cisterns was much more often satisfactory using a prone delivery (p less than or equal to 0.05 by Fisher exact test). None of these structures was opacified significantly better with the patient supine. A prone delivery is therefore recommended for most of the common indications for MCTC.