Magnetoencephalography/MRI Combo Offers Real-time Clues into Brain Functioning

Now, European scientists have effectively combined MRI scanning with the emerging imaging technology known as MEG. Researchers have bundled the two ways of imaging the brain in one helmet-like device. Because MEG records the magnetic fields generated by the brain, as brain cells fire off messages to one another, it provides scientists with a real-time insight into the brain as it processes its environment surrounding it. MRI, meanwhile, gives structural images of the brain by looking at blood flow and oxygenation levels. Combining these techniques is precisely what the MEG-MRI project, funded by the European Union (EU), did.

Ultimately, these new imaging developments could help physicians better determine what is occurring in the brains of patients, such as those with epilepsy. Another potential application would be in helping guide brain surgeons away from critical areas of a patient’s brain. It could help visualizing areas of the brain that light up when a patient talks, for example.

“You can look at streams of information as someone is reading or looking at visual images,” explained Risto Ilmoniemi, a professor of biomedical engineering at Aalto University (Finland), and the lead scientist in the project. “MRI gives the location, but not the sequence of when things happen.” For MEG to capture electrical currents, at least 1,000 neurons need to fire. “They are sending signals to each other and there are electrical currents involved, produced by neurons, and these currents can be measured. MEG measures what comes out of the brain, the electromagnetic field generated,” Prof. Ilmoniemi clarified. The MEG machine is formed like a bicycle helmet, but contains hundreds of sensors inside.

Other scientists have previously been using MEG, and separately followed up using functional MRI (fMRI) scanning. This modality gauges brain activity related to a specific function by identifying associated changes in blood flow. “We use a variety of imaging techniques for the brain, but I prefer to use MEG for a number of reasons,” said Thomas Elbert, professor of neuropsychology at the University of Konstanz (Germany). “First of all, the brain operates much faster than blood oxygen levels would indicate [which is what fMRI detects],” he told the European media company, youris.com (Brussels, Belgium), adding. “Also, fMRI is too slow and too gross when you are looking at activity, it just finds peaks of activities rather than the complex range of mountains.”

Therefore, the full range of peaks and valleys can be better seen through the use of MEG. Clinicians envision real advantages by combining the two imagine techniques. “Doing simultaneous recordings is often very valuable scientifically and clinically: measuring different types of signals at different times means you’re not sure if they’re measures of the same events,” stated Dr. Gregory Miller, a clinical psychologist at University of California, Los Angeles (USA). “When the machines are separate, the patient or research participant has to be removed from the equipment and the procedure repeated, which means the recordings are done under different circumstances. For example, there can be changes due to practice, boredom, or fatigue. Combining MEG and MRI in a single instrument would likely provide cost savings, which means not only saving money but making the technology more widely available. This is particularly important because MEG is severely underutilized, in clinical practice and in research. Second, the combination would greatly reduce the footprint in space-constrained labs and clinics, again making the capabilities available to more scientists, clinicians, and patients. Third, the combination would potentially allow near-simultaneous recordings of very different types of biological signals.”

Dr. Miller noted that MEG is safer than fMRI, provides vastly better temporal resolution than fMRI scanning, and sometimes can image more deeply in the brain than another method, called scalp electroencephalography (EEG). “So, having more access to MEG would let me study fast neural activity in deeper brain structures than I can with fMRI or EEG. This would help us address key issues about brain networks—brain circuitry—in depression, anxiety, and schizophrenia,” Dr. Miller said.

Controversy regarding whether electroencephalography (EEG), MEG, MRI, positron emission tomography (PET) imaging, or optical techniques are typically the best imaging modality is “silly,” according to Dr. Miller. “It’s been common to assume that a scientist has to choose which type of imaging method is best, but that’s like trying to decide whether a hammer or a chisel is better. For some jobs, one is clearly better. For other jobs, you need both.”

The European project has now produced a prototype that combines MEG and MRI. They hope to make improvements and have it suitable for the clinic in four to five years. The new technology should be helpful for patients, physicians, and brain researchers.

Youris dot com is a European Media Center that designs and implements media communication strategies for large research organizations and EU-funded projects.

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