MR evaluation of flow in a ventricular shunt phantom with in vivo correlation.

The ability of magnetic resonance (MR) imaging to potentially distinguish areas of fluid in motion from areas of static fluid would seem to make it possible to differentiate functioning ventriculoperitoneal shunts from non-functioning shunts in hydrocephalic patients. To test this hypothesis, a standard adult ventricular shunt system including tubing and flow control valve was tested and imaged in vitro in a flow phantom on a 1.5 T magnet with flow rates of 0, 22, 1.00, 0.50, and 0.25 ml/min. A flow void sign was present in the flow control valve on mildly and heavily T2-weighted images at all four flow rates and absent when the flow rate was 0 ml/min. In addition, we were able to image a flow void sign in the flow control valve of a patient with a functioning ventricular shunt, as well as to demonstrate absence of the flow void sign in the flow control valve in a patient with an obstructed ventricular shunt. This data suggest that MR imaging of the flow control valve in patients with ventricular shunts could yield valuable information on shunt patency.