Computed tomography based assessment of programmable shunt valve settings

Introduction: Programmable shunt valve settings can sometimes be difficult to assess using classic read-out tools, warranting a skull X-ray.

Research question: Can we use available head computed tomography (CT) scans to determine the valve settings, in order to obviate the need for additional skull X-rays?

Material and methods: The valve setting of two different programmable shunts (Codman Certas Plus® and Sophysa Polaris®) were assessed by two blinded observers in 24 patients using 65 head CT scans (slice thickness ≤2 ​mm). Using multi-planar reconstruction (MPR) tools, images were resliced according to the direction of the valve, allowing a direct readout of the valve settings. We validated our CT based method against 32 available skull X-rays.

Results: For all CT scans it was possible to assess the valve setting. No interobserver variability was found and there was a 100 ​% concordance between the CT based method and skull X-rays.

Discussion: CT based assessment of programmable shunt valve settings is feasible and reliable. It may obviate the need for additional skull x-rays when a head CT scan is available.

Conclusions: This technique can reduce radiation exposure and can be applied to historical CT imaging with unknown valve settings.