The Wonderful World of MRI

Brain image acquired by diffusion tensor imaging. Licensed by Google creative commons.

For my final blog post I though it was fitting (and about time) I wrote about my research! Brains. I’ve always loved them. I am a sucker for analyzing and interpreting human behaviour but unfortunately I did not come across much neuroscience in my undergraduate degree. I am pleased to finally pursue my interests with a research project at the Melbourne Brain Centre @ RMH.

The brain is made up of many connections and up until recently, there was no method to visualize the intricate arrangement of neurons in the brain. In 1990 the concept of diffusion tensor imaging was introduced and this field of neuroimaging is rapidly expanding. The pretty picture above represents the powerful nature of the information obtained from a Magnetic Resonance Imaging (MRI) brain scan. By understanding the simple concept of water diffusion in tissues, an MRI scanner can generate a visual arrangement of neurons in the brain.

Licensed by Google creative commons

This image represents the concept behind diffusion imaging. The idea is that water diffuses along an axon (long blue fibers), as opposed to randomly (colourful dots). Anistropy is the measure of how strong a molecule will diffuse ALONG a surface, rather than randomly (e.g. Brownian motion). By calculating the diffusion, or pull, of water in a certain direction – we can infer how neurons are arranged in the brain – and what direction they are likely to follow.

“Diffusion Tensor Imaging in Alzheimer’s Patients”

On my end of the scale, I am looking at the diffusion tensor images of patients with mild-moderate Alzheimer’s disease. Alzheimer’s disease (AD) is a neurodegenerative condition that is characterized by a decline in cognitive function. The American census bureau estimated that AD affects 1/8  people aged 65 and over and a 1/4 people over the age of 85. With an ageing population in hand, the number of cases is expected to dramatically increase in the future as life expectancies increase and the baby boomers age. There is an abundance of literature on Alzheimer’s disease and many hypotheses are present which try to justify the ‘hallmark’ of the condition, however there is no consensus as to what causes this fatal disease.

Normal brain (left) compared with AD brain (right). Licensed by Google creative commons.

I will be specifically evaluating the integrity of brain structure over time. As seen in the above picture, brain volume and integrity significantly deteriorates with Alzheimer’s disease (AD), compared with a normal brain. Patients with AD typically have a life span of generally about 10 years after diagnosis and in some cases up to 20 years. This demonstrates the debilitating nature of the disease and the requirement for interventions to be made.

Diffusion tensor imaging is currently being researched for:

  • Mapping out tracts (neural fibres) for patients with dementia
  • Mapping tracts for patients with schizophrenia
  • Defining paths for surgical tumour removal to minimize brain injury

Hopefully by the end of this two year Master’s program I would’ve mastered (pun intended) the art of neuroimaging. As well as pursuing science communication of course!

Thanks to everyone for reading my posts and contributing to the discussion, I wish you all the best in your future endeavours 🙂

Sila