Diffusion Tensor Imaging, or DTI, was first introduced by Peter Basser in 1994. It is a non-invasive, magnetic resonance imaging (MRI) technique that analyzes the anatomy of nerve cells and the complex neuronal network of the brain. DTI provides a more detailed picture of the brain’s anatomy compared to a conventional MRI. It is a highly sensitive tool that investigates brain injury as well as congenital brain development disorders.
How Does Diffusion Tensor Imaging Work?
A look at the brain
To understand the physics of the machine, it’s helpful to know a little brain anatomy. The brain is a complex organ that controls thought, memory, emotion, touch, motor skills, vision, breathing, temperature, hunger, and every process that regulates our body. Together, the brain and spinal cord make up the central nervous system. Gray and white matter are two different regions of the central nervous system.
In the brain, white matter describes the innermost section. The primary function of the brain’s white matter is to transmit information within the brain and to other parts of the central nervous system. Sometimes referred to simply as the “brain’s wiring,” this white matter is composed of nerve cell axons. The axon fibers form connections between nerve cells and connect the cerebrum with different areas of the brain and spinal cord. These long thin nerve fibers of the brain’s white matter are the parts most subject to damage and disconnection.
DTI creates pictures of brain activity
DTI data is displayed using a tractography algorithm and basically maps out the course of the neural axons of the brain. This provides a more detailed picture of brain activity than the customary diffusion weighted imaging MRI where signals are solely generated from the movement of water molecules. DTI uses the diffusion, or motion, and direction of water molecules to determine the anatomy of a brain network. It permits a virtual dissection of the white matter as well as measures the functional integrity of the network. Information gathered provides data that is based on the brain’s static anatomy and not influenced by brain functions.
Why Is DTI Useful?
As noted previously, DTI is designed to show or examine the water or fluid pathways in the white matter of the brain — the deep tissues of the brain, which are the connecting pathways between different areas of the brain.
In the case of a stroke, for example, the injured area of the brain will experience local swelling which reduces molecular movement. In the past, diffusion weighted imaging (DWI) has been used to determine the extent of damage a brain has suffered because of a stroke. This MRI technique has proven beneficial as it can show evidence of damage within minutes of the event. However, the drawback of DWI is that it only shows whether there is diffusion restriction occurring. There is no information on the direction of molecular movement.
DTI maps out the course of the neural axons of the brain. The direction of the flow is coded in color. Up and down is blue. Front to back is green. Left to right is red. If the stroke victim, or perhaps someone involved in an accident, is experiencing motor coordination issues, difficulty with speech or word finding, or memory loss, a doctor may likely order a DTI to reveal any damage to those neurons affecting that part of the brain. This is a very important tool to identify the brain injury and therefore recommend appropriate treatment.
Why Is DTI Better Than a Standard MRI?
DTI can often reveal the actual injury that is oftentimes invisible on standard MRI because only DTI can show the internal connecting tracts of the brain. DTI can see the direction of diffusion flow in any part of the brain and see the fibers. When an injury occurs, the diffusion flow is disrupted at that location. DTI sees that disruption.
What Should I Expect When Undergoing Diffusion Tensor Imaging?
From the patient’s point of view, it is just like any other MRI. You will lie down and relax in the MRI scanner where an image is obtained. There is no injection, no pill to take, no preparation to drink.
If anxiousness or claustrophobia is a concern, please feel free to discuss options with the highly knowledgeable and compassionate staff at University Medical Imaging. Providing a comfortable experience, as well as the highest image quality available for diagnostic imaging purposes, is our mission.
Please contact us if you have any questions about medical imaging.