Intra-operative 3D hologram support with mixed reality technique based on CT-MRI fusion images: operation guidance for brain brachytherapy

PURPOSE: 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). (125)I 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. D(90) and V(100) 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.