Purpose

Mixed reality (MR) is being evaluated as a visual tool for surgical navigation. Current literature presents unclear results on intraoperative accuracy using the Microsoft HoloLens 1^®. This study aims to assess the impact of the surgeon’s sightline in an inside-out marker-based MR navigation system for open surgery.

Methods

Surgeons at Akershus University Hospital tested this system. A custom-made phantom was used, containing 18 wire target crosses within its inner walls. A CT scan was obtained in order to segment all wire targets into a single 3D-model (hologram). An in-house software application (CTrue), developed for the Microsoft HoloLens 1, uploaded 3D-models and automatically registered the 3D-model with the phantom. Based on the surgeon’s sightline while registering and targeting (free sightline /F/or a strictly perpendicular sightline /P/), 4 scenarios were developed (FF-PF-FP-PP). Target error distance (TED) was obtained in three different working axes-(XYZ).

Results

Six surgeons (5 males, age 29–62) were enrolled. A total of 864 measurements were collected in 4 scenarios, twice. Scenario PP showed the smallest TED in XYZ-axes mean = 2.98 mm ± SD 1.33; 2.28 mm ± SD 1.45; 2.78 mm ± SD 1.91, respectively. Scenario FF showed the largest TED in XYZ-axes with mean = 10.03 mm ± SD 3.19; 6.36 mm ± SD 3.36; 16.11 mm ± SD 8.91, respectively. Multiple comparison tests, grouped in scenarios and axes, showed that the majority of scenario comparisons had significantly different TED values (p < 0.05). Y-axis always presented the smallest TED regardless of scenario tested.

Conclusion

A strictly perpendicular working sightline in relation to the 3D-model achieves the best accuracy results. Shortcomings in this technology, as an intraoperative visual cue, can be overcome by sightline correction. Incidentally, this is the preferred working angle for open surgery.

中文翻译：

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外科医生视线对全息图配准和混合现实瞄准的价值。

目的

混合现实（MR）正在作为外科手术的视觉工具进行评估。目前文献介绍了关于使用Microsoft HoloLens 1术精度不明确的结果^®。这项研究的目的是评估在开放式手术的基于内而外标记的MR导航系统中，外科医生视线的影响。

方法

阿克斯胡斯大学医院的外科医生对该系统进行了测试。使用定制的幻像，在其内壁内包含18个线靶十字。为了将所有导线目标分割成单个3D模型（全息图），需要进行CT扫描。为Microsoft HoloLens 1开发的内部软件应用程序（CTrue）上传了3D模型，并自动向幻像注册了3D模型。根据外科医生在注册和瞄准时的视线（自由视线/ F /或严格垂直视线/ P /），开发了4种情况（FF-PF-FP-PP）。在三个不同的工作轴（XYZ）上获得了目标误差距离（TED ）。

结果

招募了六名外科医生（5名男性，年龄在29-62岁之间）。在4种情况下，总共进行了864次测量，两次。场景PP显示XYZ轴上的最小TED，轴平均值= 2.98 mm±SD 1.33；2.28毫米±SD 1.45; 分别为2.78毫米±SD 1.91。场景FF在XYZ轴上显示最大的TED ，平均值= 10.03 mm±SD 3.19；6.36毫米±SD 3.36; 分别为16.11毫米±SD 8.91。按情景和坐标轴分组的多次比较测试表明，大多数情景比较的TED值均显着不同（p  <0.05）。无论测试的场景如何，Y轴始终显示最小的TED。

结论

与3D模型相关的严格垂直的工作视线可实现最佳的精度结果。作为术中视觉提示的这项技术的缺点可以通过视线矫正来克服。顺便提及，这是开放手术的首选工作角度。