Intricate images of our innards from MR machines have been amazing us for decades. Get set to be wonderstruck once more: specialised magnetic-resonance imaging is creating detail so fine that the function of fibres of the white matter of brains can be studied, a breakthrough that scientists hope will help revolutionise psychiatric diagnosis and treatment.
Depression is among the conditions scientists hope to unravel using diffusion MR, high-tech imaging that enables those white matter fibres to be visualised down to a single voxel (and beyond), the 3D measurement unit used for the scans. Diffusion MR techniques enable detailed examination of how a brain network is functioning and the integrity of its connectivity. So far, it has been used for research into a variety of psychiatric conditions, now the hope is to advance that to individual examinations.
“My dream is that this work will lead to more accurate diagnosis of depression and other disorders,” says Dr Jerome Maller, an MRI clinical science specialist with GE Healthcare based in Melbourne who, with the University of Sydney’s Professor Stuart Grieve, recently published an article on the topic in Molecular Psychiatry.
As the article states, this new level of imaging could potentially create for psychiatrists “a tool the equivalent of the coronary angiogram in the cardiovascular world”.
Standard MRI scans show structural information of organs, and information such as where there is a bleed or a tumour. Looking at such MRIs of the brains of concussion patients versus control patients, “generally speaking you don’t find any differences in the MR scans between the structure of brains … everything looks and measures the same,” says neuroscientist Maller.
But many studies have shown that concussion can lead to depression, a discovery that has led to closer examination of a wide spectrum of patients, from football players to the military. “We now know that the development of depression is a functional thing; there’s something going on with the function of the brain, not the structure of the brain.”
That’s where pushing the MR information to the nth voxel comes in. “With this technique, which we call tractography, we can measure how strong the connections are,” says Maller, who has published many papers around the topic and was previously a senior research fellow at the Monash Alfred Psychiatry research centre in Melbourne. “That’s where the difference will be, and that’s where the diagnosis will be: being able to predict which patients will go on to develop depression after concussion.”
Maller is using GE prototype software on the MRI console to get both better images and more information from those images than had previously been possible. Trials using diffusion MR in this way are beginning all the round the world and Maller says a new term has recently been coined: psycho-radiology. “Instead of just saying, there’s a tumour here, there’s a stroke here, there’s a haemmorhage here, we can say, ooh, that aspect is related to behaviour.”
The studies will focus on predicting which concussion patients will develop depression, and then “the next step will be to use the information to predict who will respond to which treatment and therefore vastly improve prognosis. It’s an exciting time to be in MR.”