Article
Magnetic guided neuronavigation: A reliable method for tracking ventricular catheter tip
Magnetisch geführte Neuronavigation: Eine verlässliche Methode zur Navigation der Spitze von Ventrikelkathetern
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Published: | April 23, 2004 |
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Outline
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Objective
Free-hand accurate placement of ventricular catheters can be difficult in cases of small ventricels, abnormal ventricular anatomy or occipital placement. Misplacement of the catheter due to deviation at the rigid ventricular ependyma cannot be controlled by conventional neuronavigation systems during insertion. The aim of this study was to evaluate the accuracy of a magnetic tracking system of the catheter tip compared to conventional optical guided neuronavigation systems.
Methods
The sensor (4 mm magnetic coil, diameter 0.95 mm) of the flexible stylet, placed at the tip of the instrument, was tracked by a 3D magnetic system (AURORA Tracking System, Northern Digital Inc controller®), based on a Kolibri® (Brainlab AG, Munich) Image Guidance System. The accuracy of the magnetic tracking system was compared to optical tracking by geometrical analysis, cadaver studies and in 30 patients with hydrocephalus of different origins. Possible intraoperative magnetic fields and metallic instruments were tested for their influence on the navigation system.
Results
In cadaver tests, the accuracy of the system was very similar to optical tracking systems (which only track the proximal end of the probe). Tracking the sensor at the tip of the instrument also enabled the system to control correct placement of the catheter even when the stylet bends during insertion. The influence of magnetic fields and metallic instruments in the operating theatre was low and could be easily avoided. In 30 patients with hydrocephalus the accuracy of magnetic neuronavigation was estimated to be below 5mm. Even in patients whose heads were not fixed in a rigid mayfield pin fixation, accuracy of the system was maintained.
Conclusions
Magnetic guided neuronavigation proved to be a very reliable method for the control of catheter tip, particularly in difficult cases. It represents a valuable addition to the present navigation systems that already exist.