Interactive 3-D technology guides neurological surgeons through the brain during procedure

Aug 1 2007

Jefferson Hospital for Neuroscience is one of first medical centers in the U.S. to develop and begin using translational, interactive 3-D technology to map the human brain and help guide neurological surgeons during epilepsy surgery and procedures to remove malignant brain tumors.

This imaging technology can help surgeons better determine the location of tumors for removal. The 3-D mapping also helps guide surgeons during epilepsy procedures to see exactly where electrodes have been placed in the brain and portions of the brain that may have to be removed to help stop seizures.

"Neurosurgery is strongly dependent on image guidance, and in order to fully explore the massive amount of data provided by modern imaging devices, neuroscientists and neurosurgeons are steadily asking for improved visualization techniques, said radiologic researcher Song Lai, Ph.D, Associate Professor of Radiology and Director of MRI Physics, Jefferson Medical College of Thomas Jefferson University, whose team developed the software, dubbed MediCAD (computer assisted diagnostic), over the last few years.

"This multi-disciplinary project represents a unique combination of advanced imaging technology development with significant clinical applications, bringing together different but complementary expertise, including MRI physicists, computer scientists, neurosurgeons, and neuroradiologists," Dr. Lai noted.

DTI (diffusion tensor imaging) and fMRI (functional magnetic resonance imaging) images of the brain are integrated and downloaded, using the MediCAD software, onto PCs in the operating room (OR). This allows the surgeons to view almost real-time digital map of a patient's brain and better perceive brain activity information. MediCAD also allows the surgeons to virtual 'slice, the brain into sections, zoom in for close-ups of sections of the brain and even rotate the image in various directions.

"Therefore, incorporation of DTI and fMRI in pre-surgical planning holds great promise in advancing our ability to reach the main goal of neurosurgery, i.e., removing a targeted lesion while minimizing postoperative neurological deficits by avoiding damage to the involved functioning white matter fiber tracts and cortical gray matter," said Dr. Lai.

"This exciting technology also allows us to see the special relationship between the lesions and structures affected by the tumors," said neurosurgeon David Andrews, M.D. "We can see whether the tumors are infiltrating or displacing the white matter tracts and this information has both practical and prognostic significance.

'specific to brain tumor patients, it is important to be able to distinguish between infiltrative and expansive tumors, since the latter growth pattern allows a complete resection without neurologic compromise," Dr. Andrews noted. "We have also learned that the expansive tumors lead to a far better prognosis than the infiltrative tumors."

During a typical epilepsy surgery, neurological surgeons and neurologists would view conventional MRI or CATscan images of a patient's brain prior to surgery and then ,visualize where implanted electrodes were in the brain during the procedure," explained neurologist Christopher Skidmore, M.D., of the Jefferson Comprehensive Epilepsy Center. This technology allows us to better understand the relationship between areas where seizures are coming from and vital brain structures so that a safe and effective surgery can be performed with the goal of stopping the patient's seizures."

Patients who undergo epilepsy surgery have a number of advanced diagnostic imaging modalities; including MRI, fMRI, DTI, fcMRI, PET Scanning and implant electrodes, said Ashwini Sharan, M.D., neurosurgeon at the Jefferson Comprehensive Epilepsy Center

"The MediCAD technology will serve as a platform for integration and joint analysis of all this information in the future," Dr. Sharan said. Without such computer back-up, it's impossible for us to even comprehensively analyze the information which we have. This will, in the long run, only improve the care on epilepsy patients.

As part of this new 3-D imaging process, a patient's brain is typically scanned the day before surgery in order to obtain the most up-to-date imaging data.

"Due to the time constraint between scanning and the actual surgery, neurosurgeons require a tool that can provide detailed integrated information interactively in a timely fashion," said Dr. Andrews.

The images are then sent through an electronic archival system know as PACS (picture archiving and communication system) to computers in the OR.

The need for this technology was developed out of questions raised in the past by neurological surgeons and scientists, said Dr. Lai, about where tumors are located in juxtaposition to other parts of the brain including white matter fibers and at what points do these fibers go inside a tumor. The fibers carry signals back and forth between areas of the brain and the spinal cord and each fiber is crucial to a particular aspect of how the mind communicates with the body.

"With these questions in mind, a multi-modal visualization system was developed which allows for performing these query tasks in real time and produces quantitative results," said Dr. Lai. "Pilot studies on both healthy subjects and patients with brain tumors have suggested that our software package can provide intuitive and quantitative answers and further assist in neurosurgical planning."

The developed software is fast, does not require any pre-processing beyond standard fMRI analysis and is flexible enough to be incorporated into existing complex medical visualization systems, Dr. Lai noted.