Research Grants 1997-1998

Development of Brain Phantom Models for Head Injury Research

William W. Orrison, Jr., MD
New Mexico Reg. Federal Medical Center, Albuquerque, New Mexico

According to the Brain Injury Association, 2 million individuals in the United States sustain a traumatic brain injury (TBI) each year. Of those, 100,000 individuals die as a result of the trauma and approximately 80,000 suffer lifelong debilitation. There is a pressing need for improved understanding of the mechanisms of TBI and the development of tools to combat its occurence. This requires research into the basic types of head injury for which there are limited models other than animals.

Currently, TBI research is conducted on animals in the form of pre-planned brain lesion studies to determine predictive factors, and human subjects who have suffered TBI. Post-TBI studies on humans yield little information about what happens to the brain during traumatization. Through animal modeling of specific brain trauma, information can be obtained about particular consequences of experimentally identified forms of TBI. However, in addition to the inhumaneness of such forms of analysis, there are still severe limitations on the ability to visualize the brain during the act of traumatization. Due to these limitations, TBI remains extremely difficult to research.

The New Mexico Institute of Neuroimaging (NMIN) has performed extensive CT and MR evaluations of consequences of TBI. Additionally, NMIN staff are recognized leaders in the field of functional brain imaging. To begin study on what occurs during the event of human brain trauma, we have developed a prototype phantom brain model made of silicone mixtures which looks, feels and acts strikingly similar to real brain tissue.

We are requesting support to further modify the composition of the brain phantom so that it accurately mimics physical properties and MR analyses of real brains. While these phantoms would not approximate real brains in function, we feel that they could be very useful in the research of TBI through controlled analysis of the dynamics of trauma as it occurs. That data would then be compared to existing data on brain structure and that would in turn be analyzed against what we know about functional aspects of the brain. Our long range objective is for this technology to be used to alleviate the use of animals in lesion studies and to assist in the development of more functional protective devices and preventive strategies, as well as providing better diagnostic and treatment capabilities for patients suffering TBI.

Specifically, in the first year of the program, we propose to add to our existing brain models materials such as calcium and gadolinium to give the model physical properties similar to real brain tissue and to enhance the ability to obtain accurate MR and CT images. We will apply measurements of basic mechanical properties of stress and strain to the phantoms in order to determine if they possess similar physical properties of real brains, including shape memory. We will also conduct a review of the relaxation literature for the different types of brain tissue so that other properties can eventually be introduced into the phantom matrix.

Later phases of the program will include the addition of damage indicators, such as synthetic bruises in the form of microscopic vesicles of material that when disrupted, mix to form colors as with Ph sensitive dyes. Other augmentations will include the addition of more complicated structures including a brainstem and nuclei. In order to conduct these experiments we will also be developing clear skull models that will contain the brain in a closed system surrounded by synthetic cerebrospinal fluid and comprise accurate suspensions points. We anticipate that by using photolithography of real data we will be able to create accurate matches of real brain/skull systems. The models can then be used to investigate the dynamics as well as the physical effects of TBI, through evaluation by MRI and possibly high speed photographic techniques.