Intraoperative imaging, navigation and monitoring

Neurosurgery involves significant risks due to the intricate anatomy and delicate structures of the brain and spine. Developing techniques to improve surgical accuracy, thereby minimizing these risks, has been a key focus throughout the evolution of neurosurgery. This thesis explores intraoperative navigation, imaging and monitoring technologies designed to enhance accuracy, efficiency and seamless integration into the surgical workflow.

Study I was a systematic review on the use of hybrid operating rooms in neurosurgery. It was found that publications on hybrid operating rooms mainly focus on vascular and spinal uses, the main advantages being the possibility to easily acquire pre-, intra- and postoperative images, thereby increasing surgical precision.

Study II aimed to evaluate the feasibility of performing intraoperative MRI by using a non- dedicated MRI scanner in the radiology department and to outline the workflow. The study showed that this method is feasible, safe and only adds about an hour to the surgical procedure. This extra time is no longer than that reported in studies with a dedicated MRI scanner.

In Study III the registration accuracy between traditional surface matching and automatic image registration was compared in patients undergoing cranial surgery. The mean accuracy for surface match registration was 6.6 + 3.1 mm and for automatic image registration 1.0 + 0.3 mm. Thus, automatic image registration was found to be superior to surface matching.

In Study IV the registration accuracy between surface matching and automatic image registration was compared in patients undergoing spinal surgery. Automatic image registration at 1.20 + 0.42 mm was not found to be inferior to surface matching at 1.94 + 0.64 mm. The accuracy of both methods was clinically acceptable for spinal surgery, but automatic image registration minimized user errors and provided a more standardized workflow.

Study V was a feasibility and accuracy study, in which augmented reality navigation was used in combination with a conventional navigation system to place pedicle screws in a spine phantom. An augmented reality head mounted device was used to plan and place 48 screws with a clinical accuracy of 94%. The addition of the augmented reality device is feasible and contributes benefits in the planning and minimally invasive placing of pedicle screws. The accuracy achieved is in line with conventional navigation systems and other publications on augmented reality devices.

Study VI was a retrospective study describing our workflow when conducting intraoperative neurophysiological monitoring for intramedullary spinal tumor surgery. In addition, intraoperative neurophysiological data from 70 patients were analyzed for correlation between intraoperative signal change and postoperative neurological outcome. A highly trained neurophysiologist was responsible for monitoring our workflow and always present in the operating room. A complete loss of somatosensory evoked potential response intraoperatively was significantly associated with sensory deficits and lower modified McCormick scores at short and long-term follow-up. Intraoperative loss of motor evoked potential correlated with a significant decline in modified McCormick scores at long-term follow up.

List of scientific papers

I. Gharios M*, El-Hajj VG*, Frisk H*, Ohlsson M, Omar A, Edström E, Elmi-Terander A. The use of hybrid operating rooms in neurosurgery, advantages, disadvantages, and future perspectives: a systematic review. Acta Neurochir (Wien), 2023, 165, 2343-2358. https://doi.org/10.1007/s00701-023-05756-7

II. Frisk H, Persson O, Fagerlund M, Jensdottir M, El-Hajj VG, Burström G, Sunesson A, Kits A, Majing T, Edström E, Kaijser M, Elmi-Terander A. Intraoperative MRI without an intraoperative MRI suite: a workflow for glial tumor surgery. Acta Neurochir (Wien), 2024, 166, 292-300. https://doi.org/10.1007/s00701-024-06165-0

III. Frisk H, Jensdottir M, Coronado L, Conrad M, Hager S, Arvidsson L, Bartek J Jr, Burström G, El-Hajj VG, Edström E, Elmi-Terander A, Persson O. Automatic image registration provides superior accuracy compared to surface matching in cranial navigation. Sensors (Basel). 2024 Nov 18;24(22):7341. https://doi.org/10.3390/s24227341

IV. Frisk. H, Burström. G, Persson. O, El-Hajj. V.G, Coronado. L. Hager. S, Edström. E, Elmi-Terander. A. Automatic image registration on intraoperative CBCT compared to Surface Matching registration on preoperative CT for spinal navigation: accuracy and workflow. Int J Comput Assist Radiol Surg, 2024, 19, 665-675. https://doi.org/10.1007/s11548-024-03076-4

V. Frisk H, Lindqvist E, Persson O, Weinzierl J, Bruetzel LK, Cewe P, Burström G, Edström E, Elmi-Terander A. Feasibility and Accuracy of Thoracolumbar Pedicle Screw Placement Using an Augmented Reality Head Mounted Device. Sensors (Basel), 2022, 22, 522. https://doi.org/10.3390/s22020522

VI. Frisk H*, Margaryan G*, Buwaider A*, Sargsyan D, El-Hajj VG, Majing T, Singh A, Fletcher- Sandersjöö A, Persson O, K.E. Persson J, Edström E, Elmi Terander A. Intraoperative Neurophysiological Monitoring in Intramedullary Spinal Surgery - Workflow, Setup and Outcomes. [Manuscript]
*Shared first authorship