Research Portfolio: Image-Guided Surgery and Brain Mapping
Principle Investigator: Alexandra J. Golby M.D, of Brigham and Women’s Hospital
Goals and Objectives:
Functional brain mapping techniques used before and during neurosurgical procedures ensure the safest possible therapy for meningioma, including neurosurgical treatment for tumors located in eloquent areas. Neurosurgeons and their teams will increasingly use these techniques to perform less invasive and more effective operations. With funding from the BSF, Dr. Alexandra Golby has hired a team of extraordinary scientists working collaboratively to advance the field of image-guided surgery and functional brain imaging. By developing brain mapping techniques to better understand the functional anatomy of the brain and applying these techniques to surgical planning and in the operating room, Dr. Golby and her team are ensuring healthier outcomes and improving the quality of life for patients of meningioma and other brain tumors.
Several techniques exist that are able to take detailed pictures of the brain’s anatomy and of the brain in action. These functional brain mapping techniques include functional MRI (fMRI), Magnetoencephalography, diffusion tensor imaging, transcranial magnetic stimulation, electrocorticography, and others. Using these techniques, a road map revealing some of the critical areas of the brain, such as areas responsible for movement, sensation, and speech, can be made. The goal of Dr. Golby’s project is to continue developing these techniques so that they can be useful clinically. For example, for patients with meningiomas or other tumors or lesions in or next to the brain, brain mapping helps doctors determine the relationship between the critical brain areas and the tumor(s) prior to surgery.
Over the last decade, mapping techniques, like neurosurgery techniques, have become progressively less invasive, that is, less risky and less painful for patients, Along with this trend has come the opportunity to obtain images from more areas of the brain, in more types of patients (including children), under a greater variety of circumstances. As part of their work, Dr. Golby’s team combines information from multiple brain mapping methods to obtain the most reliable and complete data, overcoming the strengths and weaknesses intrinsic to different methods capturing different types of information.
Project Summary and Update as of 9/30/06
Presurgical brain mapping: Dr. Golby’s team has preformed presurgical brain mapping on approximately 90 patients using fMRI paradigms (including language, memory, visual, and motor) tailored to the individual’s clinical need. These studies have helped Dr. Golby’s team localize eloquent cortical areas pre-surgery. This progress along with the development of new protocols for the acquisition of more detailed DTI images and the implementation of new algorithms is making complex data more easily interpretable to the clinician. Study results were published this year in the International Journal of Medical Robotics and Computer Assisted Surgery.
Computer programming and translational biomedical engineering: Work performed last year by Dr. Golby’s team using surface normals at electrode sites to extrapolate the positions of intracranial electrodes that are positioned beyond the extent of the craniotomy and out of the reach of the hand-held tracking probe were presented at the IEEE International Symposium on Biomedical Imaging. Currently, Dr. Golby’s team is engaged in a collaborative effort to measure and compensate for intraoperative brain shift, which would allow the accurate registration of pre-operative data to the intraoperative position of the brain, making this data much more useful. Results from this study have been published in Medical Image Computing and IEEE Trans Med Imaging.
Functional MRI studies of memory for surgical planning. In a study demonstrating a new way to assess altered laterality of memory encoding, Dr. Golby’s team was able to differentiate patients with altered lateralization from healthy subjects. Published in Neuroimage, these results can be useful for surgical planning of epilepsy and tumor patients. Dr. Golby’s team will continue investigating the effect of successful encoding and of language lateralization on memory encoding lateralization in the MTL.
Studies in healthy subjects to develop and validate protocols
Dr. Golby’s group has also collected 20 fMRI and DTI datasets from healthy controls to develop protocols and paradigms that can eventually be used in patients. These include developing language mapping paradigms (see below) and diffusion tensor imaging techniques (see below).
Computer programming and translational biomedical engineering
The team completed a study correlating fMRI results with direct cortical stimulation sites via integration in the 3D Slicer application. The group is also exploring ways to integrate DTI tractography within the GE instatrak neuronavigation system, the most recent approach involving the creation of labelmaps describing the 3D models, which can then be loaded by the system and fused with the clinical data. A study has been conducted demonstrating how the use of surface normals at electrode sites can be used to extrapolate the positions of intracranial electrodes that are positioned beyond the extent of the craniotomy and out of reach of the hand-held tracking probe (Figure 1).
Figure 1. Three-dimensional model of the brain shows estimated location of electrodes collected during surgery (in red) and corrected location (in blue) using an algorithm developed by the Golby Lab team.
Multi-modality Language mapping
The project is collecting and analyzing MRI, fMRI, DTI, EEG, and MEG data to study language function. The group designed and tested custom data acquisition paradigms for the functional mapping of language—intended for use in both non-invasive and invasive technologies. We have collaborated closely with Dr. Steve Stufflebeam, the director of the MEG laboratory at MGH, designing, testing, and implementing data acquisition protocols for the collection of non-invasive functional EEG and MEG data. Data from fMRI was collected and language analysis was completed on approximately 14 normal volunteers, and 4 patients. The Golby group has also collected and analyzed language MEG in approximately 8 normal volunteers, and 2 patients.
From these data, we have submitted abstracts for 3 scientific poster presentations, all of which were accepted for presentation. Including the Winner of 2005 Excellence Award, 2005 M.E.G. Clinical Applications Conference, Xylocastro, Greece.
Figure 2. In this figure blue models represent MEG language localizations, red models represent fMRI language localizations, brown cords represent white matter tractography by DTI, yellow models represent MEG interictal discharge foci, the green model represents a tumor lesion, and the red tags represent intra-operative language mapping sites ascertained by intra-operative testing in the operating room. The results illustrated in these two patients represent state-of-the-art visualization and integration of a wide variety of functional and structural imaging techniques.
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