Cine phase-contrast MR imaging in normal pressure hydrocephalus patients: relation to surgical outcome.

Phase-contrast cine MR flow imaging through the aqueduct was used to establish the diagnosis of normal pressure hydrocephalus (NPH), and to predict outcome after shunting. From 1990-1994 16 patients, who were participants in the Dutch Normal Pressure Hydrocephalus Study [3], were studied. The patients included in this study met clinical and CT-scan criteria as described in this study, underwent cine phase-contrast MR imaging prior to placement of a CSF shunt, and had a follow-up 12 months after the operation. Claustrophobic patients, patients with a pacemaker or extremely agitated patients were excluded. Normal Flux was calculated in each patients, as the average difference in caudal and rostral flux (Fdiff) +2 times standard deviation (0.97 cc/sec) [2]. The clinical outcome was measured with a modified scale of activities of daily living (ADL) as described by Rankin. Of the 16 patients, 8 could not be evaluated due to restlessness during MR measurements, disabling cerebral vascular accidents or death before the end of the follow-up period. Of the remaining 8 patients, 5 had a normal flux, of which only one improved. Two patients had a Fdiff twice the normal range, which improved in both patients. One patient had no measurable flux, consistent with an aqueduct stenosis; he too improved. Overall, there was a concordance of MR findings with final outcome after shunting in 7 out of 8 patients. This pilot study, therefore, support the need to further evaluate flow with MR imaging techniques to select patients with shunt responsive NPH.