Introduction

The study investigated whether intra-operative 3D hologram, a computer graphics model of the brain, with mixed reality (MR) technique based on computed tomography-magnetic resonance imaging (CT-MRI) fusion images could be helpful during brachytherapy for brain metastasis.

Material and methods

A patient with relapsed brain metastasis was reported. Pre-operative CT and MRI image fusion was performed, with software developed by our center and the Chinese University of Hong Kong. 3D polygon data segmented from pre-operative CT-MRI fusion images were registered into HoloLens (Microsoft Corporation, Redmond, WA, USA). 125I seed implantation was performed under MR guidance.

Results

Interventional surgeons could share the same hologram and move the hologram from their respective angles, while wearing the HoloLens without any monitors. The intra-operative hologram offered good visualization of the skull, tumor location, and main vessels around the tumor during brain brachytherapy of a patient with brain metastasis. The interventional surgeons could easily compare the patient’s actual anatomy with the hologram before and during the brain brachytherapy procedure. D90 and V100 of post-operative plan and pre-operative plan were 131.8 Gy vs. 132.0 Gy and 94.8% vs. 94.0%, respectively. The patient’s imaging findings together with clinical symptoms were greatly improved at 3 and 6 months after the implantation.

Conclusions

This initial experience suggests that the use of the intra-operative hologram with MR technique based on CT-MRI fusion images helped in brachytherapy guidance. Further research is needed to explore the potential of this approach in neuro-navigation.