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 patient, 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, supports the need to futher evaluate flow with MR imaging techniques to select patients with shunt responsive NPH.