Objective: Augmented-reality (AR) has appeared in almost every area of industry and science in recent years.

At the University of Debrecen we have been working on digital radiography and 3D holographic visualisation of neurosurgical images since 2018. Our aim was to transform the familiar orthogonal plane imagery into a more realistic, easier to understand 3D structure, and display it on a 3D playback device (Hololens2). Subsequently, the next objective was so-called “non-rigid” navigation. Our goal was to “fit” the displayed 3D hologram onto the patient’s head under surgical conditions.

Findings: Our experience has shown that studying individual patient anatomy in 3D in preoperative preparation has made the surgical preparation exponentially easier. With see-through holographic imaging, craniotomy planning has been made accurate, giving the opportunity for minimal invasiveness.

Compared to existing navigation or desktop software, with the help of Hololens2 we can plan in real 3D. Moreover, in the software we have written (Holospital), we can pre-mark anatomical points, annotations and reminders that can be used in the intraoperative environment.

In the operating room circumstances, “non-rigid” navigation involves projecting the scaled preoperative radiological images onto the patient’s head without the patient’s head being fixed: the camera of the Hololens finds the spatial position of the patient based on a QR code fixed near the patient’s head.

The Holospital system can also be used in a sterile environment after the preoperative setting. By placing the device on the surgeon’s head, using sterile hand gestures, all the functions of the system can be used.

The system has been used most in vascular and tumor-surgery cases. The 3D data was most helpful in the management of complex structural arteriovenous malformations.

Conclusion: In the 21st century and with the current technological advances, it is imperative that 3D augmented reality is also gaining ground in neurosurgery. Preoperative preparation and intraoperative use increase surgical precision and safety, ultimately improving morbidity statistics.