Evaluation of the precision of operative augmented reality compared to standard neuronavigation using a 3D-printed skull

Abstract

OBJECTIVEAugmented reality (AR) in cranial surgery allows direct projection of preregistered overlaid images in real time on the microscope surgical field. In this study, the authors aimed to compare the precision of AR-assisted navigation and standard pointer-based neuronavigation (NV) by using a 3D-printed skull in surgical conditions.METHODSA commercial standardized 3D-printed skull was scanned, fused, and referenced with an MR image and a CT scan of a patient with a 2 × 2–mm right frontal sinus defect. The defect was identified, registered, and integrated into NV. The target was physically marked on the 3D-printed skull replicating the right frontal sinus defect. Twenty-six subjects participated, 25 of whom had no prior NV or AR experience and 1 with little AR experience. The subjects were briefly trained in how to use NV, AR, and AR recalibration tools. Participants were asked to do the following: 1) “target the center of the defect in the 3D-printed skull with a navigation pointer, assisted only by NV orientation,” and 2) “use the surgical microscope and AR to focus on the center of the projected object” under conventional surgical conditions. For the AR task, the number of recalibrations was recorded. Confidence regarding NV and AR precision were assessed prior to and after the experiment by using a 9-level Likert scale.RESULTSThe median distance to target was statistically lower for AR than for NV (1 mm [Q1: 1 mm, Q3: 2 mm] vs 3 mm [Q1: 2 mm, Q3: 4 mm] [p < 0.001]). In the AR task, the median number of recalibrations was 4 (Q1: 4, Q3: 4.75). The number of recalibrations was significantly correlated with the precision (Spearman rho: −0.71, p < 0.05). The trust assessment after performing the experiment scored a median of 8 for AR and 5.5 for NV (p < 0.01).CONCLUSIONSThis study shows for the first time the superiority of AR over NV in terms of precision. AR is easy to use. The number of recalibrations performed using reference structures increases the precision of the navigation. The confidence regarding precision increases with experience.

Holographic mixed-reality neuronavigation with a head-mounted device: technical feasibility and clinical application

“…In contrast, in augmented reality, users observe virtual objects in a physical environment. 3 Mixed reality, derived from augmented reality, refers to the input of physical scene information into a virtual environment and enables interactive digital data to be displayed over the physical environment. Commercial head-mounted devices (HMDs), such as HoloLens (Microsoft Corp.), make these imaging technologies more applicable to many fields, including healthcare, 4 education, 5 and psychology.…”

Evaluation of the effect of standard neuronavigation and augmented reality on the integrity of the perifocal structures during a neurosurgical approach

“…The tasks were performed in a standard surgical condition as previously described, 2 with the aim to mimic a minimally invasive surgical approach through a limited craniotomy size. The wire box was held in a Mayfield head clamp with the reference array affixed to it.…”

“…The development of preoperative image-based neuronavigation systems have allowed a reduction in postoperative patient morbidity due to the abil-ity to adapt the surgical strategy intraoperatively to respect healthy tissues. [1][2][3][4][5] Although standard neuronavigation (NV) offers a permanent localization of structures of interest intraoperatively, it has several disadvantages; the neurosurgeon must look at dedicated NV screens, transpose 2D images onto 3D real images through the surgical microscope, and turn his or her focus away from the surgical field. 2,6 The use of ABBREVIATIONS AR = augmented reality; NV = neuronavigation; Q1 = first quartile; Q3 = third quartile.…”

“…[1][2][3][4][5] Although standard neuronavigation (NV) offers a permanent localization of structures of interest intraoperatively, it has several disadvantages; the neurosurgeon must look at dedicated NV screens, transpose 2D images onto 3D real images through the surgical microscope, and turn his or her focus away from the surgical field. 2,6 The use of ABBREVIATIONS AR = augmented reality; NV = neuronavigation; Q1 = first quartile; Q3 = third quartile.…”

“…Therein, we showed the superiority of AR over NV regarding the precision-to-target, due to the permanent possibility to recalibrate the AR according to the signature structures. 2 Although precision is an integral component of surgical safety, our experiment did not analyze the integrity of the perifocal structures with the use of NV and AR.…”