Feature - In this case, it is brain surgery

New, grid-based imaging technology has the potential to change neurosurgery. Image courtesy of Phil Beard, sxc.hu

To the edge

Branching through your brain, a complex system of arteries, capillaries and veins feeds the organ that allows you to think. While the shape of each person’s network is similar in the basics to everyone else’s, it is unique in the particulars. This presents a challenge for neurosurgeons.

A new type of three-dimensional imaging and processing tool, based upon grid-computing, stands ready to change the way doctors perform neurosurgery. Called HemeLB, it won the Transformational Science Challenge Award at TeraGrid ’08 in Las Vegas, US, last month.

The current technology neurologists use allows for a patient’s vasculature to mapped by the processing of MRI scans. These scans, created with magnetic resonance imaging, use magnetic fields and radio waves to create pictures of bodily tissues. Typically these are two-dimensional images: just a slice. Images in three dimensions are cutting-edge. Just beyond that ‘edge’ is a new type of imaging and processing that stands ready to change the way doctors perform neural surgery.

Funded by both the EPSRC in the UK and the NSF in the US,  the HemeLB blood flow fluid solver is at the heart of a larger infrastructure project known as GENIUS, or “Grid Enabled Neurosurgical Imaging Using Simulation,” run by a group of British computational scientists and neurologists working out of University College London, University of Manchester and the National Hospital for Neurology and Neurosurgery, London.

Using HemeLB, it is now possible to visualize and predict changes in patient-specific cerebral blood flow.

“We are taking static MRI images and adding value to them. This will enhance the tools that doctors base their decisions on,” says Peter Coveney, University College London.

Progress made with HemeLB, starting with (top left) a 2D MRI slice of a human head and then the images derived from it. Top right: first, a 3D map of vasculature is created, in which  parameters—velocity and pressure—are set. Next (bottom left), a simulation of blood pressure, yellow areas show higher pressue blood received from the neck.  Third and last (bottom right), a detailed, interactive visualization of blood velocity. Illustration courtesy of Peter Coveney, University College London

Map-making

HemeLB processes MRI images, reconstructs a patient’s vasculature and builds a map. This map shows blood vessels topography, blood velocity and pressure, and which vessels are likely stressed—possible sites of a future aneurysm. An area of abnormally low pressure is likely a site of blockage. The tool is also interactive and able to predict how these parameters change in the event of a surgical embolisation (a therapeutic procedure where an obstruction is placed in a blood vessel to redirect the flow).

“When a surgeon blocks the site of a malformation in surgery, it is not possible to know how this will affect all regions of the brain,” says Steven Manos, also of University College London. “What you would like to do is perform virtual surgery to see how pressure and blood flow are affected elsewhere. This will aid in surgical planning.”

The tool is not in clinical use yet; it is still being tested and validated. However it may be launched in production quite soon.

“We would love to see it in use by the end of 2008,” says Coveney. “The infrastructure to use HemeLB is in place: the tool is developed and we have the computing power.” 

GENIUS uses grid power and, in the spirit of interoperability, is a trans-Atlantic project: computing resources come both from TeraGrid in the US and from the National Grid Service in the UK.

—Danielle Venton, iSGTW