Contribution of 3D CISS MRI for the post therapeutic monitoring of obstructive hydrocephalus

This report describes the use of the recent three-dimensional Fourier trans form constructing imaging in the steady state (CISS) MR sequence in the man agement of obstructive hydrocephalus. It is a gradient-echo imaging techniq ue with high resolution which remains sensitive to flow. it enables locatin g the obstruction and determining the upstream impact. It provides anatomic al information about third ventricle (V3) morphology and relationships usef ul before ventriculostomy. Twenty patients with obstructive hydrocephalus a t the level of cerebral aqueduct or posterior V3 underwent sagittal 3DFT-CI SS acquisition, supplemented by frontal, axial and coronal reformations in the cerebral aqueduct axis. 9 patients were examined after ventriculostomy with the same protocol CISS-3DFT allows goon visualization of the cerebral aqueduct and diagnosis of the underlying cause of obstruction (malformation , tumor), sometimes better than classical sequences. In case of complete ob struction, the flow-related signal void is usually absent in the cerebral a queduct or V3. The position of V3 floor and its relationship with the rip o f basilar artery are well analyzed. The dilatation of the anterior V3 reces ses is a better sign of activity of hydrocephalus - and then of therapeutic al indication - than classical transependymal resorption signs which are no t always present in chronic longstanding adult hydrocephalus. Of the 9 vent riculostomy patients seven hall linear flow-related signal void through V3 floor from anterior V3 to basal cisterns on the postoperative MR study. Thi s flow void confirms patent ventriculostomy.