PURPOSE: In the operating theatre surgeons are accustomed to using spatially navigated tools in conjunction with
standard clinical imaging during a procedure. This gives them a good idea where they are in the patients’ anatomy but
doesn’t provide information about the type of tissue they are dissecting. In this paper we demonstrate an integrated
system consisting of a spatially navigated surgical electrocautery combined with real-time molecular analysis of the
dissected tissue using mass spectrometry.
METHODS: Using the 3D Slicer software package, we have integrated a commercially available neurosurgical
navigation system with an intra-operative mass spectrometer (colloquially referred to as the intelligent knife, or iKnife)
that analyzes the charged ions in the smoke created during cauterization. We demonstrate this system using a simulated
patient comprised of an MRI scan from a brain cancer patient deformably registered to a plastic skull model. On the
skull model we placed porcine and bovine tissues to simulate cancerous and healthy tissue, respectively. We built a
PCA/LDA model to distinguish between these tissue types. The tissue classifications were displayed in a spatially
localized manner in the pre-operative imaging, in both 2D and 3D views.
RESULTS: We have demonstrated the feasibility of performing spatially navigated intra-operative analysis of tissues by
mass spectrometry. We show that machine learning can classify our sample tissues, with an average computed
confidence of 99.37 % for porcine tissue and 99.36% for bovine tissue.
CONCLUSION: In this paper we demonstrate a proof of concept system for navigated intra-operative molecular
analysis. This system may enable intra-operative awareness of spatially localized tissue classification during dissection,
information that is especially useful in tumor surgeries where margins may not be visible to the unassisted eye.
Keywords: image guided therapy, intra-operative mass spectrometry, iKnife, 3D Slicer, open-source, rapid evaporative
ionization mass spectrometry (REIMS)