The endonasal patient reference tracker: a novel solution for accurate noninvasive electromagnetic neuronavigation

Area of Science:

• Neurosurgery
• Medical Devices
• Surgical Navigation

Background:

• Electromagnetic (EM) navigation offers continuous guidance but relies on suboptimal patient reference trackers.
• Current trackers are either invasive (bone-screwed) or less accurate (skin-attached).
• A new approach is needed for precise, non-invasive patient referencing in EM navigation.

Purpose of the Study:

• To introduce and evaluate a novel, non-invasive electromagnetic (EM) reference method using a nasal tracker (NT).
• To assess the stability and accuracy of the NT compared to a standard skin-adhesive tracker (ST).
• To determine the feasibility of the NT for enhancing EM navigation in surgical procedures.

Main Methods:

• Developed a nasal tracker (NT) by integrating an EM coil array into a nasal tamponade for insertion into the inferior nasal meatus.
• Validated NT stability ex vivo on cadaveric skull bases under simulated surgical conditions (patient positioning, skin traction).
• Conducted a clinical feasibility study comparing NT and ST accuracy against a ground-truth reference tracker throughout routine surgeries.

Main Results:

• Ex vivo, the NT demonstrated high stability with median deviation of 0.4 mm (range 0.0-2.0 mm).
• In 13 clinical cases, the NT showed significantly greater stability than the ST (median deviation 1.3 mm vs 4.0 mm, p = 0.002).
• The standard tracker (ST) lost accuracy during draping and flap fixation, unlike the NT.

Conclusions:

• The endonasal EM patient tracker is feasible and offers high procedural stability, both ex vivo and clinically.
• This non-invasive innovation combines high precision with patient comfort.
• The NT has the potential to significantly improve EM navigation accuracy in future neurosurgical applications.