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Brain injury brain functioning imaging

There are also three exciting imaging studies that focus on brain "function" rather than just on "structure". These techniques allow one to show the effect of a TBI on the brain without having to rely solely on the testimony of experts. Of course, expert testimony would be needed to try to lay the evidentiary foundation for these imaging studies. Admissibility is much more challenging than for the Structural Imaging Studies

Imaging Studies

PET scans (positron emission tomography)
fMRI (functional MRI)
SPECT scans (single photo emission computed tomography)

1. PET scans:

PET is an acronym for "positron emission tomography." This technique has been available since the 1970's but has undergone a good deal of advancement in quality since then. It relies on a small amount of radionuclide (a tracer or isotope) that is injected into the body. The tracer is chemically mixed into a biologically active molecule which means that is one the body will absorb and use. The most common molecule used is FDG which is a sugar analogue (i.e. a cousin) of glucose. The goal is to wait and see how the brain absorbs and metabolizes the glucose. If the brain does not absorb or metabolize the glucose at all or does so poorly, there is abnormal metabolism (hypometabolism) and that is significant because it is evidence that the brain in the area being studied either is not functioning or not functioning efficiently.

PET scans provide dynamic information about the working brain which can help illustrate brain injury that might be missed by less sensitive structural imaging like CT or MRI scans.

The scanner creates 3D colored images of the brain with excellent resolution. PET scans can show deficits in areas of the brain responsible for attention, memory, mood regulation etc. For example, CT scans of anoxic brain injuries (lack of oxygen) or hypoxic brain injuries (reduced oxygen) due to carbon monoxide poisoning (COI), anesthesia or birth injuries are often negative. Often the only way to visualize these brain injuries is with a PET scan.

The admissibility of a PET scan into evidence at trial depends on a strong expert foundation. Opponents of admissibility argue that the PET scan is not a generally accepted or scientifically reliable method of measuring brain function. They cite Daubert v. Merrell Dow Pharmaceuticals, Inc, 509 U.S. 579 (1993) and Frye v. United States, 54 App. D.C. 46, 47, 293 F. 1013, 1014 (1928). Frye held that scientific evidence can be admitted onl if it has gained a general acceptance in a particular field. Daubert held that Federal Rules of Evidence, Rule 702 superseded Frye as the proper standard for determining the admissibility of scientific evidence in the federal courts. Rule 702's two part test for determining admissibility of an expert opinion is:

  1. Does the opinion of the expert relate to a matter of scientific, technical or specialized knowledge? and
  2. Will the expert's testimony be helpful to the trier of fact in determining a fact in issue in the case?

As PET scanning continues to advance, it will be easier to establish that this imaging technique is admissible. The highest resolution available is HRRT (high resolution research tomography). There are only five in the US and thirteen in the world. A resource for HRRT PET scanning is the University of California, Irvine Brain Imaging Center in Irvine, California (949-824-7867). Anyone attempting to admit a PET scan into evidence should make sure to retain a knowledgeable expert to lay the proper foundation.

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2. fMRI:

This is the acronym for the "functional MRI." CT and MRI scanning can give one a 3D model of organ structure or anatomy but fMRI takes this a step further. It measures brain activity and is based on the same technology as the MRI. Both techniques use a strong magnetic field and radio waves (signals) to create detailed images. Whereas traditional MRI creates images only, fMRI looks at blood flow in the brain to detect areas of activity i.e. changes in blood flow otherwise known as hemodynamics.

Oxygen rich blood and oxygen poor blood behave differently in a magnetic field. They have different magnetic resonances. Contrast in blood oxygen response enable the scanner to map images of brain activity to tell physicians which parts of the brain are more or less active. Increased blood flow translates to increased brain activity and vice versa.

fMRI has been around since the 1990's and is primarily used as a research tool. It has dominated the brain mapping field because changes in blood flow and blood oxygenation are closely linked to brain activity. Its advantages are that is uses no radiation like X-ray,CT, PET and SPECT scans and has no risks. It produces very high resolution images. It also can record signals from all regions of the brain unlike EEG (electroencephalogram) which focuses mainly on the surface of the brain.

Although it is a revolutionary technique it is not without disadvantages. It is expensive. It only looks at blood flow and not the activity of individual brain cells (neurons). Because a brain area "lights up" on an fMRI scan for decreased blood flow, is not conclusive proof that a particular type of brain activity is being compromised. One has to deduct this because individual neurons are not visualized.

fMRI scans are not routinely admitted into evidence at trial. The challenge is that this scan is not yet generally accepted and reliable reliable scientific evidence as discussed above with the admissibility of PET scans.

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3. SPECT scans:

This is an acronym for "single photo emission computed tomography." It is essentially a CT scanner and a radioactive tracer. It provides information regarding blood flow to the brain. The tracer is injected and then is absorbed as it is circulated in the blood stream. A camera detects the photos and this information is transmitted to a computer and cross-sectional images are converted to 3D format. The study shows how the blood flows through the brain.

SPECT scans have been available since the 1970's. They are cheaper than PET scans but PET has higher resolution. fMRI is a similar measurement and is safer because no isotopes are used.

The experienced Lakeland personal injury attorneys at Allen & Abaray, P.A. aggressively pursue accident injury cases throughout the state of Florida. If you or a loved one has been injured in an auto accident, truck accident, slip and fall accident, or have suffered any type of injury because of someone else's negligence, call 1-863-669-9999 today for a free consultation.

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