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Dr. Terry Thompson


Dr. Terry Thompson Ph. D.

Brain Imaging

Brain injury is a significant problem for premature infants. In the past few years, there has been a great deal of interest in applying magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) to investigate brain pathology associated with neonatal brain injury. Such work should provide further insight into the way in which insults to the developing brain influence brain maturation and might impact upon the individual's function in later life. It may also provide a means of monitoring the early effects of therapeutic intervention.

Recent studies in animals and humans have demonstrated that a non-conventional MRI technique, known as diffusion imaging, has great potential for assessing brain injury. This technique measures the relative mobility of the intracellular and extra-cellular water. Potentially this diffusion imaging has the capability of delineating the orientation of white matter tracts within the brain. Thus, it should be ideal for investigating the influence of brain injury on the postnatal development of such tracts.

The objective of this research project is two-fold. Firstly, we plan to develop and implement a method of MRI, MRS and diffusion weighted MR suited for studies of neonates on our specialized neonatal MRI system that operates at 3 Tesla. (The higher magnetic field strength provides an improved image resolution and time). Secondly, we plan to apply these methods to study the effects of low-grade intraventricular hemorrhage (this is a result of blood leaking out of the blood vessels in the brain) in premature infants. Our hypothesis is that these small hemorrhages will produce subtle changes in the biochemistry of the brain, which can be detected by our techniques.

Cardiac Spectroscopy

Despite spending over seven billion dollars per year on the treatment and prevention of cardiac disease, heart attacks are still the leading cause of death among Canadians. Using Nuclear Magnetic Resonance (MR) techniques, it is possible to non-invasively assess the function and energy status of the heart muscle immediately following a heart attack. The effects of new drugs designed to minimize the amount of permanently damaged tissue can be monitored by these techniques.

MR Spectroscopy measures energy compounds and intracellular pH of the cardiac cells. These measurements allow us to monitor energy metabolism and potentially distinguish between viable and non-viable myocardium. Additionally, real time anatomical images of the beating heart can be produced using magnetic resonance imaging (MRI). From these images, the ejection fraction can be calculated. This is a measure of the ability of the left ventricle to perform the necessary function of supplying blood to the body. Using MRI the final extent of permanent heart muscle damage can be determined from contrast-enhanced images. Correlating the above measurements we can accurately assess the outcome following a heart attack.

The objective of this research project is two-fold. Firstly, we plan to develop and implement a method of MRI, MRS and diffusion weighted MR suited for studies of neonates on our specialized neonatal MRI system that operates at 3 Tesla. (The higher magnetic field strength provides an improved image resolution and time). Secondly, we plan to apply these methods to study the effects of low-grade intraventricular hemorrhage (this is a result of blood leaking out of the blood vessels in the brain) in premature infants. Our hypothesis is that these small hemorrhages will produce subtle changes in the biochemistry of the brain, which can be detected by our techniques.

A new cardiac drug has been tested with the expectation of increasing the amount of viable or healthy tissue following a heart attack. By using all of the above noninvasive MR techniques in an in vivo animal model, we have shown that this drug improves the immediate recovery of the heart (as measured by the ejection fraction), but the lack of corresponding metabolic improvement suggests that a higher and more frequent dose of the drug should be studied.

We will be improving the MR protocol by moving to our new 3T MR system and we will also be adding the capabilities of Positron Emission Tomography (PET) to study the energy utilization and viability of the heart. Both of these imaging modalities are (PET installed Spring of 2003) situated at the LHRI.

In-vivo Studies of Cellular Water Using Magnetic Resonance

Human beings are primarily made of water. In healthy individuals, the amount of water ranges from about 80% in utero to about 50% in the elderly. There are a variety of disease process, however, that alter the amount and distribution of water in our tissues, including cancer, diabetes, sepsis, and multiple sclerosis. A clear understanding of the amount and distribution of water is therefore important to assess healthy tissues and potentially diagnosis disease using Magnetic Resonance techniques.

This line of research is directed at (1) improving magnetic resonance (MR) techniques that measure tissue water non-invasively and (2) increasing our understanding of the distribution of water in healthy muscle. Conventional MR techniques that measure tissue water only obtain 2-12 data points. Our laboratory has developed a new technique and used it to collect 2000 data points in the forearm muscle. Interestingly, the results suggested that the majority of water was not only distributed between the extra- and intracellular environments as previously thought, but also among distinct regions within the cell. A subsequent study also showed that the amount of water within the cell appears to shift from one region of the cell to the other during intense exercise, demonstrating a new way to study muscle metabolism. Next, we used our technique to investigate the effects of creatine monohydrate, a popular dietary supplement, on water distribution in muscle. This study revealed that the 1-2 kg weight gain induced by short-term creatine supplementation is consistent with an increase in intracellular water in skeletal muscle. This work has demonstrated a new technique for in vivo water assessment and has brought us a step closer to understanding the distribution of water in living tissue.

Physics, Physics & Biology, Engineering, Medical Physics/Biophysics are typical undergraduate backgrounds of students involved with this project.

If you are interested in this project please contact .