Understanding the Role and Importance of Diffusion Tensor Imaging in Personal Injury Cases

DTI Basics

Diffusion Tensor Imaging (DTI) is a type of magnetic resonance imaging (MRI) technique that is able to detect brain injuries that affect the integrity of white matter tracts, which are the lines of communication in your brain. Without white matter, the brain would consist of four different sections, or lobes, that are responsible for various functions, but could not work together. Imagine you’re a remote employee working on an important team project, but your internet is down and you are unable to communicate with anyone else in your office. You have all the files necessary to complete your part of the project, but you can’t share them with the rest of your team.  White matter tracts are like your brain’s internet connectivity – allowing all the sections of the brain to communicate with each other. When these are damaged, the different lobes of your brain cannot talk to each other, leading to common symptoms such as memory problems, mood changes, and balance issues.

DTI works by measuring the diffusion of water molecules within the white matter tracts, which means it looks towards the molecules’ movements. In normal white matter, water diffuses in the direction of a specific white matter tract. When the molecules encounter barriers, such as cell membranes, DTI can map the directionality of white matter tracts. It can detect when these water molecules move in a more chaotic manner which would indicate damage caused by a brain injury. These disruptions to the normal organization of white matter tracts can indicate issues such as traumatic brain injury, stroke, or multiple sclerosis.

For example, in a TBI, the impact can cause damage to axons (the long, thin projections of nerve cells that form the white matter tracts). This damage can disrupt the directional diffusion of water molecules (what we touched on above), leading to changes in the DTI signal that can be visualized on a DTI map. These changes can help identify the location and extent of the injury, as well as the severity of the damage.

Think of marbles rolling down a track. A stick is placed in front of them and does not allow the marbles to flow down as they should. Now they start bouncing all over the place. DTI can locate that bouncing and tell us that there was likely an injury to the track. The severity of that bouncing tells us how severe the injury is. Where the bouncing and chaos starts tells us where the injury is.

Overall, DTI has become a valuable new tool to not only to detect brain injuries and their severity, but also monitor their progression.

DTI in Legal Cases

In legal cases, DTI can be used as a tool to provide evidence of brain injury or damage, particularly in cases of traumatic brain injury (TBI). What sets DTI apart from, say, MRI, is that it can be used to demonstrate how an injury has affected an individual’s cognitive or motor functions, which is extremely relevant in personal injury cases. For example, suppose an individual has suffered a TBI as a result of a car accident. In that case, DTI could be used to demonstrate how the injury has affected their ability to drive or perform other tasks.

When it comes to minor brain injuries, often an MRI will not reveal any noticeable structural damage. On the other hand, DTI’s intricate dive further into the inner workings of the brain can detect such minor brain injuries. And remember, just because a brain injury is minor, does not mean it does not affect one’s everyday life and potentially come with lifelong side effects.

Admissibility of DTI Evidence in Personal Injury Cases

The State of Colorado follows what is called the Daubert standard in determining the admissibility of scientific evidence into trial. The case, Daubert v. Merrell Dow Pharmaceuticals Inc., 509 U.S. 579 (1993), was a United States Supreme Court Case that held that the admissibility of scientific evidence is based on determining whether there is valid methodology based on: (1) whether the theory or technique in question can be and has been tested; (2) whether it has been subjected to peer review and publication; (3) its known or potential error rate; (4) the existence and maintenance of standards controlling its operation; and (5) whether it has attracted widespread acceptance within a relevant scientific community. In order for the scientific evidence to be admitted, all five of those elements must be met.

In personal injury cases, defense attorneys will spend a lot of energy on fighting the admissibility of scientific evidence because it can hold a whole lot of weight with a jury, especially if it can prove that an “invisible injury” is much more extensive than it seems on its surface. That is why these relatively new technologies such as DTI are so integral to the legal field  – it gives the injured party’s trial team more ammo to present to the jury. So, it is almost inevitable that a defense attorney will attack DTI because of the damning evidence that it can present. They may go after its reliability by trying to present various outlier studies to bar its admission. Or they may attack how it is relatively new and there is not enough evidence to understand DTI’s true effectiveness.

Fortunately for the good guys, DTI is already gaining a lot of traction as an acceptable method to determine the extent of brain injuries. Courts across the country have admitted DTI into evidence leaving the defense to try and counter it at trial. However, a knowledgeable, properly trained, and well-spoken expert for the plaintiff will generally have minimal issues convincing a jury of DTI’s effectiveness in diagnosing and understanding the severity of brain injuries.