Neuroimaging

Introducing the Neuroimaging Team

As part of our Melbourne Brain Centre Feature Week series, we were able to provide an insight into the research being undertaken by their Neuroimaging team.  To begin the week, Professor Roger Ordidge (Chair of Imaging Science at The University of Melbourne) explained how the Neuroimaging team uses cutting-edge technology to investigate a variety of neurological disorders, including multiple sclerosis.

While Professor Ordidge provides a high-level overview of the team’s work, the following research summaries, provided by Dr Scott Kolbe and Dr Anneke Van der Walt, go into greater detail about the types of research projects being undertaken.

UNDERSTANDING THE REASONS BEHIND DIFFERENT OUTCOMES OF OPTIC NEURITIS

Optic neuritis (inflammation of the optic nerve) is a common side-effect of multiple sclerosis (MS) and leads to many sight-related difficulties, including blurriness, impaired colour recognition and problems with contrast sensitivity. In the majority of these cases, vision spontaneously improves within the first few months. However, in some cases, chronic visual disability is observed following the initial optic neuritis. The reasons behind this are poorly understood.

In this study by Kolbe et al, visual disability and the correlation with white matter injury was studied amongst 23 people, who had both MS and optic neuritis affecting one eye. Results were compared between both the affected and unaffected eye, as well as against 14 neurologically healthy, age and sex matched controls. White matter injury was assessed specifically in the area of the brain associated with the visual pathway, as well as the whole brain.

The results indicated that long-term visual disability after optic neuritis was correlated with white matter injury outside of the visual pathway, most commonly in the frontal lobe. On the other hand, visual problems observed in eyes not affected by optic neuritis were most commonly associated with white matter injury in the visual pathway. It is hoped that a better understanding of the underlying causes of visual disability in people with MS could lead to more accurate prognoses and in the long-term, the development of better treatment options.

This is a summary of “Diffusion Tensor Imaging Correlates of Visual Impairment in Multiple Sclerosis and Chronic Optic Neuritis” by Kolbe et al, published in Investigative Ophthalmology & Visual Science, Feb 2012.

A NEW TECHNIQUE TO ASSESS OUTCOMES OF OPTIC NEURITIS

Optic neuritis (inflammation of the optic nerve, (ON)) causes visual loss and is a common early symptom of multiple sclerosis (MS). Patients with ON present to hospital early and identifying measurements of optic nerve function that can be used to predict clinical and neurological outcomes has become a major focus of research. Recently, an MRI technique known as diffusion tensor imaging (DTI) has been shown to identify differences in the earliest stages of optic neuritis. DTI can be used as a measure of the extent of nerve damage (Axonal loss) after ON.

To assess the effectiveness of early changes in DTI to predict long-term outcomes for people with ON, Van der Walt et al undertook a study of 40 people with ON and 10 healthy controls and assessed them within 48 hours of presenting to hospital, and again at 1,3, 6 and 12 months. Early changes in DTI as well as the initial visual loss, retinal swelling and loss of conduction of nerve signals were measured and compared against neurological, clinical and visual outcomes at 12 months after the episode of ON. DTI was markedly reduced in the affected optic nerve at 1 month after onset and this reduction corresponded to the extent of axon damage at 6 and 12 months after ON. In addition, a prolonged recovery time in DTI markers for up to 3 months was able to predict the degree of visual recovery at 12 months after ON. The investigators concluded that treatment to normalise the level of this marker could improve both axon survival and visual outcomes. Early reduction in DTI markers could be used to select patients with a likely poor recovery who would best benefit from new treatments targeting nerve protection in MS.

This summary comes from “Optic Nerve Diffusion Tensor Imaging after Acute Optic Neuritis Predicts Axonal and Visual Outcomes” by Van der Walt et al, published in PLOS One, December, 2013.

The week finished with another two videos presented by Professor Roger Ordidge.  The first provided an explanation of Magnetic Resonance Imaging (MRI) and addressed some of the most commonly asked questions about this medical imaging technique.

The second was focussed more specifically on the Melbourne Brain Centre’s new Siemens PET/CT scanner and explained how it may help people living with multiple sclerosis.