OBJECTIVEPlacement of a ventricular drain is one of the most common neurosurgical procedures. However, a higher rate of successful placements with this freehand procedure is desirable. The authors’ objective was to develop a compact navigational augmented reality (AR)–based tool that does not require rigid patient head fixation, to support the surgeon during the operation.METHODSSegmentation and tracking algorithms were developed. A commercially available Microsoft HoloLens AR headset in conjunction with Vuforia marker-based tracking was used to provide guidance for ventriculostomy in a custom-made 3D-printed head model. Eleven surgeons conducted a series of tests to place a total of 110 external ventricular drains under holographic guidance. The HoloLens was the sole active component; no rigid head fixation was necessary. CT was used to obtain puncture results and quantify success rates as well as precision of the suggested setup.RESULTSIn the proposed setup, the system worked reliably and performed well. The reported application showed an overall ventriculostomy success rate of 68.2%. The offset from the reference trajectory as displayed in the hologram was 5.2 ± 2.6 mm (mean ± standard deviation). A subgroup conducted a second series of punctures in which results and precision improved significantly. For most participants it was their first encounter with AR headset technology and the overall feedback was positive.CONCLUSIONSTo the authors’ knowledge, this is the first report on marker-based, AR-guided ventriculostomy. The results from this first application are encouraging. The authors would expect good acceptance of this compact navigation device in a supposed clinical implementation and assume a steep learning curve in the application of this technique. To achieve this translation, further development of the marker system and implementation of the new hardware generation are planned. Further testing to address visuospatial issues is needed prior to application in humans.
Patient tracking is an essential part in a surgical augmented reality system for correct hologram to patient registration. Augmented reality can support a surgeon with visual assistance to navigate more precisely during neurosurgical interventions. In this work, a system for patient tracking based on infrared markers is proposed. These markers are widely used in medical applications and meet the special medical requirements such as sterilizability. A tracking accuracy of 0.76 mm is achieved when using the near field reflectivity and depth sensor of the HoloLens. On the HoloLens a performance of 55–60 fps is reached, which grants a sufficiently stable placement of the holograms in the operating room.
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