Stanford White Matter and Fiber Tractography Lab
White matter forms the “wiring” of the brain, allowing communication between distant regions. Before the introduction of magnetic resonance imaging (MRI), our knowledge of white matter structure and function came from patients with neurological disorders and dissection of post-mortem specimens. The introduction of MRI-based tractography methods in the early 2000’s permitted researchers and clinicians to visualize living white matter structure in healthy and diseased brains at a level of detail previously unheard of.
Tractography for Anatomical Studies
The human brain’s white matter structure was originally described in the 19th century by pioneers including Broca, Wernicke and Dejerine. Their descriptions often came from post-mortem dissections and remained unchanged for approximately 100 years. This lack of advancement was largely technological and in contrast to other fields of medicine which saw a Golden Age of knowledge during the 20th century. The introduction of tractography at the beginning of the 21st century permitted neuroscience researchers to conduct studies of living human white matter across large numbers of subjects with healthy and diseased brains. Furthermore, tractography allowed specific white matter structures to be isolated from surrounding tissues, permitting detailed study of their connectivity and composition. Though tractography is barely 20 years old, we have been at the forefront of implementing it in neuroanatomical studies and are working toward ushering in a new “Golden Era” of neuroscience knowledge.
A primary goal of neuroanatomical research is to correlate structure with function. Understanding the function of both gray and white matter is critical for neurosurgeons who must operate on these areas. Unnecessary damage to any of these functional regions may produce deficits of function which may severely affect a patients’ quality of life. Though tractography alone does not give functional information there are various ways for tractography to contribute to functional understanding:
- By correlating the known cortical terminations of white matter with functional data derived from functional magnetic resonance imaging (fMRI), magnetoencephalography, lesion data, positron emission tomography (PET) or other functional methods.
- By correlating white matter anatomy with evidence gained from electrical stimulation of brain regions during surgery.
We have pioneered use of tractography for pre-surgical planning and have conducted pre-operative tractography in over 150 tumor cases. Pre-surgical tractography allows the surgeon to visualize how a tumor (or other lesion) disrupts surrounding white matter structures, causing clinical symptoms. By visualizing white matter structures affected by tumors, the surgeon is able optimize their surgical approach and maximize removal of diseased tissue while minimizing “collateral” damage to surrounding tissues. This leads to fewer post-operative complications for the patient.
Tractography for Stroke Research
Strokes affect 795,000 people each year in the United States and are a leading cause of disability. The speech-production area of the brain is often affected and many stroke patients suffer from long-term speech problems (aphasia).
The brain is an ever-changing organ, and its cells constantly undergo structural alterations - a phenomenon known as plasticity. We have applied our tractography techniques to trace white matter changes in stroke patients undergoing intensive speech and language therapy.