Effect of marker position and size on the registration accuracy of HoloLens in a non-clinical setting with implications for high-precision surgical tasks

Abstract

Purpose Emerging holographic headsets can be used to register patient-specific virtual models obtained from medical scans with the patient’s body. Maximising accuracy of the virtual models’ inclination angle and position (ideally, ≤ 2° and ≤ 2 mm, respectively, as in currently approved navigation systems) is vital for this application to be useful. This study investigated the accuracy with which a holographic headset registers virtual models with real-world features based on the position and size of image markers. Methods HoloLens® and the image-pattern-recognition tool Vuforia Engine™ were used to overlay a 5-cm-radius virtual hexagon on a monitor’s surface in a predefined position. The headset’s camera detection of an image marker (displayed on the monitor) triggered the rendering of the virtual hexagon on the headset’s lenses. 4 × 4, 8 × 8 and 12 × 12 cm image markers displayed at nine different positions were used. In total, the position and dimensions of 114 virtual hexagons were measured on photographs captured by the headset’s camera. Results Some image marker positions and the smallest image marker (4 × 4 cm) led to larger errors in the perceived dimensions of the virtual models than other image marker positions and larger markers (8 × 8 and 12 × 12 cm). ≤ 2° and ≤ 2 mm errors were found in 70.7% and 76% of cases, respectively. Conclusion Errors obtained in a non-negligible percentage of cases are not acceptable for certain surgical tasks (e.g. the identification of correct trajectories of surgical instruments). Achieving sufficient accuracy with image marker sizes that meet surgical needs and regardless of image marker position remains a challenge.

Mixed-Reality-Assisted Puncture of the Common Femoral Artery in a Phantom Model

“…Considering that CFA puncture was performed repetitively on an immobile phantom model and in an experimental setting using an advanced navigation system, the results of this study demonstrate the necessity of further improvements in positional accuracy of the registration process before transfer of this technology into clinical practice can be suggested. Previous studies have demonstrated that the number, size, and position of the radiopaque markers may play an important role for accurate pattern recognition [34]. Other factors, such as calibration errors, are also known to have an influence on positional error and these sources of error should be subject to systematic investigation in the future [34,35].…”

“…Previous studies have demonstrated that the number, size, and position of the radiopaque markers may play an important role for accurate pattern recognition [34]. Other factors, such as calibration errors, are also known to have an influence on positional error and these sources of error should be subject to systematic investigation in the future [34,35]. Furthermore, not only could technological improvements advance the applicability of MR technology in surgical guidance, but also the use of creative synergies of existing technology.…”

Mixed Reality in der Gefäßchirurgie – ein Scoping Review

“…Auch der Einsatz von MR-assistierter Navigation am Patienten wurde bereits beschrieben. Lu et al [24] [23,26,30]. Sollen anschließend in der MR-Umgebung ohne Einsatz von Röntgenstrahlung Katheter navigiert werden, so ist darüber hinaus ein Tracking der einzelnen zur Anwendung kommenden chirurgischen Instrumente notwendig.…”

P‐58: Measurement of AR Displays in Positioning Accuracy

“…Perez-Pachón et al, 2021 [10] investigated the effect of marker positioning and size on the registration accuracy of HoloLens in a non-clinical environment with applications for high-precision surgical tasks. In surgery, image-pattern-recognition tools recognize the images and compute registration using image markers.…”