A group of engineers recently set out to quiet down the noise of magnetic resonance imaging (MRI) systems at the source. They developed a combination of hardware and software called Silent Scan, a neuro acquisition application that brings MR scanner noise near background sound levels approximately 77 decibels.
An MR scanner can generate noise in excess of 110 decibels, enough to rival a rock concert. There is a good reason why this happens. “An MRI scanner is like a huge version of a speaker in your home,” said engineer Bryan Mock, who manages GE Healthcare’s (Chalfont St. Giles, UK) MRI products in Waukesha, IL, USA. “They both have magnets inside and a coil of wire that carries electric current,” Mr. Mock said.
The current that flows through the coil inside the MRI speaker creates a magnetic field that moves a magnet attached to a flexible membrane that creates sound. The MR scanner utilizes changes in the current to generate a magnetic field to image the body. Because the coil and the magnet inside the MRI scanner are fixed in place, the machine does not play classical music, but vibrates and makes noise. MRI manufacturers conventionally reduced the noise by snuffing it out with foam or rubber or foam. “But that’s just covering it up,” Mr. Mock remarked.
“It’s a completely new way to image,” Mr. Mock said. “It’s like going from techno beat to ambient music. They both make you feel good in the end, you just get there differently. Your speaker is still working but the membrane is not moving as much.”
The technology works by minimizing changes in the current during the imaging process. Smoother current means fewer vibrations and less noise. “How we change the magnetic field is really the breakthrough of the Silent Scan technology,” Mr. Mock explained. He noted that the software is altering the current “a tiny amount for every bit of information that we need.”
Newer, stronger hardware helps to reduce the vibrations even further and eliminate bad images and image artifacts. “You need both pieces to work correctly for the machine to be quieter and give good images,” Mr. Mock stated.
Hospitals in Europe and the United States are already working with Silent Scan. Spectrum Health (Grand Rapids, MI, USA) was the first hospital in the world to implement the technology. It also used the software as part of research collaboration with GE Healthcare. “The response from our patients has been very gratifying,” said Spectrum Health radiologist Dr. Mark DeLano. “The scans are essentially silent.”
With Silent Scan, patients and families will be able to experience a more relaxing scanning environment even being able to converse during the scan. Silent Scan is available on GE’s 1.5T and 3.0T systems currently available for routine head examinations.
Patients told Dr. DeLano that “the Silent Scans don’t make any noise are greatly preferred compared to the hammering sound of conventional MRI scans. This reduces their anxiety about the procedure.” He noted that that he is “particularly looking forward to providing this to our pediatric patients, claustrophobic patients, and our patients being scanned in the operating room where the noise of the traditional MRI can be disruptive.”