Functional MRI creates a series of images that capture blood oxygen levels in parts of the brain that are responsible for movement, perception, and cognition. Functional MRI, which reveals the brain in action, differs from standard MRI, which provides a static image.
"This is a quantum leap in what we're able to do", stated Dr. James Leach, a brain-imaging specialist - neuroradiologist - with UC Radiology and the Neuroscience Institute. "It has significantly affected how neurosurgeons plan to do neurosurgery and how much tumour they can remove while still avoiding critical areas of brain function." Stated Christopher McPherson, M.D., a neurosurgeon with the Neuroscience Institute: "It's easier and safer for the patient, and it can reduce the length of surgery."
The fMRI technology is manufactured by BrainLAB and marketed as iPlan BOLD - blood oxygen level dependent - MRI Mapping. It has been used successfully in 12 surgical cases so far at University Hospital.
The technology involves collaboration between the Mayfield Clinic, one of the United States' major physician organisations for clinical care, education, and research of the spine and brain, and UC Radiology, which purchased the BrainLAB planning station hardware. Both physician practices are closely affiliated with the Neuroscience Institute, an international centre of excellence located at University Hospital and UC.
Neurosurgeons have never simply guessed at where critical areas of the brain begin and end. First and foremost, they are trained to understand the fundamentals of the brain's anatomy. But boundaries are not always clear, and the growth of a tumour can cause functional areas to shift from their original locations. Large tumours can cause these critical regions to shift dramatically.
To identify functional areas of the brain that should not be harmed, neurosurgeons traditionally have applied a small electrical stimulation with a wand-like instrument during surgery. If a motor area is stimulated, for example, the patient's hand will move. Electrical stimulation has had drawbacks, however. "Stimulating the brain with an electrode can cause a seizure", Dr. McPherson stated. "And to accurately identify language areas in some cases we had to keep the patient awake. We also were forced to make a larger opening of the skull and expose more areas."
The need for electrical stimulation also can lengthen a surgical procedure by 30 to 60 minutes. While neurosurgeons make the transition to the fMRI-assisted navigation technology, they are continuing to perform brain stimulation to double-check for accuracy. Thus far, Dr. McPherson said, the double checks have confirmed the technology's accuracy while suggesting that the technology may make brain stimulation unnecessary for many surgeries in the future.
The new BrainLAB equipment also enables physicians to integrate diffusion tensor imaging (DTI), which provides a map of critical white-matter tracts in the brain. "White-matter tracts", stated Dr. Leach, "are like the electrical connections between different parts of a house. If you disrupt that connection, you have no communication between those two areas."
FMRI scans are performed several days prior to surgery on a 3 Tesla scanner at West Image, a Cincinnati imaging facility owned by Set Shababian, M.D. "We perform various language, motor and vision tasks with the patient in the MRI scanner", Dr. Leach explained. FMRI scanning takes approximately 75 minutes, about 30 minutes longer than traditional MRI. The DTI scan, which takes five minutes, is performed in the same setting.
Dr. Leach processes those images, highlighting the location of speech and movement areas and white matter tracts. He also highlights the tumour location, then imports all of the information into BrainLAB's navigation software at University Hospital.
The Neuroscience Institute, a regional centre of excellence at the University of Cincinnati and University Hospital, is dedicated to patient care, research, education, and the development of new treatments for stroke, brain and spinal tumours, epilepsy, multiple sclerosis, trauma, Alzheimer's disease, and Parkinson's disease.
The Mayfield Clinic, which is affiliated with UC's Department of Neurosurgery, includes 21 neurosurgeons and treats 20.000 patients from 35 states and a dozen countries in a typical year. Mayfield's neurosurgeons are active participants in important clinical trials and have pioneered surgical procedures and instrumentation that have revolutionized the medical art of neurosurgery for brain tumours and neurovascular diseases and disorders.
UC Radiology is affiliated with UC's Department of Radiology and Division of Radiation Oncology and is a member of UC Physicians. Staffed with 40 radiologists and five radiation oncologists, UC Radiology takes part in more than 200.000 procedures each year.