Neuro Advances


Diffusion Tensor Imaging as a
Pre- and Intra-Operative Tool

 

Magnetic resonance imaging (MRI) has a wide variety of applications in the field of neuroimaging. The plasticity of MRI has resulted in ongoing development of many new applications utilizing this imaging modality, one of the latest of which is the technique of diffusion tensor imaging (DTI), now available for outpatients at the Cottage center for Advanced imaging and for inpatients within Santa Barbara Cottage Hospital.

 

DTI is related to diffusion weighted imaging (DWI), a widely used MRI sequence that is the most sensitive technique available for detection of early acute stroke. DWI maps the amount of random motion of water molecules within the brain. Areas of the brain undergoing infarction experience

•    Director's Letter
•    Saving the Brain 2009
•    Radiosurgery
•    Stroke Center Certification
•    AVM Case Study
•    Diffusion Tensor Imaging
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  Intramedullary Tumors
  Hans Keirstead

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cellular changes that restrict the random motion of water molecules, and this change can be detected with the DWI technique. DTI goes a step further; it maps the net direction of the motion of water molecules within the brain.

 

“DTI is a technique that allows us to indirectly map white matter tracts—the information highways of the brain,” says Sean Snodgress, MD, neuroradiologist at Cottage Center for Advanced Imaging. “Imagine a large number of ping-pong balls moving in random directions in a box. Because the movement is random, no net direction of movement exists. If a series of dividers are placed within the box, however, the motion becomes less random—the balls now preferentially move parallel to the dividers. If we can detect the net direction of movement three dimensional diffusion tensor images are created to demonstrate the course of white matter tracts within the brain. DTI allows for surgical planning designed to avoid white matter tracts, which convey neural signals crucial for movement, speech, vision and other important brain functions. Of the ping pong balls, we can infer the orientation of the dividers.

 

“The ping pong balls are analogous to water molecules in the brain, and the dividers to the white matter tracts that connect neurons in the brain and spinal cord,” continues Dr. Snodgress. “DTI identifies the direction of movement of those water molecules in high detail, and from that motion we can infer and map the course of the white matter tracts in the brain.”

 

DTI is performed on the 3T magnet at the Cottage Center for Advanced Imaging. The DTI sequence adds approximately five minutes of imaging time to a routine brain MRI.

 

 

Sean Snodgress, MD, neuroradiologist

 

Once a DTI scan has been completed, the information is transferred to a workstation in the hospital operating room, where the images can be reviewed and manipulated by the neurosurgical staff prior to and during surgeries.

 

   
 

Three-dimensional diffusion tensor images are created to demonstrate the course of white matter tracts within the brain. DTI allows for surgical planning designed to avoid white matter tracts, which convey neural signals crucial for movement, speech, vision, and other important brain functions.

 

 

“By using DTI images pre- and intra-operatively, a neurosurgeon can localize the white matter tracts in the area of a tumor or other lesion to be resected,” says Dr. Snodgress. “The surgical approach can be altered to spare the white matter tracts responsible for vital functions, such as speech and movement. This can have a very significant effect on the patient’s level of functioning following surgery.”

 

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DTI has been available at Cottage for approximately six months.

 

“The push to get DTI at Cottage was initiated by Dr. Zauner,” says Dr. Snodgress, referring to Alois Zauner, MD, neurosurgeon. “It is his goal to equip Cottage with the most advanced technologies in neuroimaging.”

 

The addition of this new technology represents one of many ways radiologists and surgeons at Cottage collaborate to provide the safest and most effective therapy.

 

“DTI allows us to visualize anatomy that cannot be characterized using any other imaging technique,” says Dr. Snodgress. “It provides a tool which can significantly impact patient outcomes.”

 

For more information about DTI and other imaging services available at Cottage Center for Advanced Imaging, visit www.cottageadvancedimaging.com.