What's the catch with this amazingly silent MRI?

So, GE’s released a new line of MRI scanners (or maybe just an update for their software and internal hardware) hat are supposedly some 30 decibels quieter than the previous generation. They’ve even posted a youtube video showing the difference. GE Healthcare's Silent Scan Technology Quiets MRI Noise - YouTube .

So, what are the ways they could fake (or “enhance”) the video or results without doing actually lying? (which could make them liable for fraud)?

Given the statements at the end of the video I’m inclined to believe them. Unfortunately, my cynical skeptic side doesn’t give up that easily.

Moved to General Questions from Great Debates.

What would be the motive for GE, a corporation highly protective of their reputation for medical devices, to lie about something as trivial as the amount of sound reduction? Sure it’s trivial to fake a video like the one you linked-- I could do it in 10 seconds using their original footage and a copy of Sony Vegas or Adobe Premiere, why would they?

I don’t have a factual answer to your question, other than to say I find it quite believable that with some effort they could reduce the loudness of an MRI.

EDIT: If you’re really concerned (and in a position to actually influence a purchase order for MRI scanners), call up your local GE rep and ask for him to reproduce the results with you observing. I’m sure they’d arrange that, if it meant a sale.

MRIs are loud because of magnetostrictive effects.
When the imaging coils are pulsed, the coils change shape (minutely) and make noise.
This is an unwanted effect - presumably, GE has figured out a way to make the coils stiffer and less likely to deform under load, making the machine quieter.

I’m guessing the catch is in the low to mid six figures, as compared to louder models with otherwise equivalent capabilities.

All technologies advance with time, and making things quieter is one of the most straightforward ways in which a technology can be advanced. Which makes the GE claims perfectly believable, especially coming from a long-established company that’s long been making machines of this sort.

It could also (or additionally) be due to new insulating and damping materials which impede sound transmission. They could even be doing clever acoustical things within the machine to direct sound away from the chamber.

there isn’t the same switching on and off but continuous change.

I saw a MRI scanner promoted a few years ago which claimed to be silent. They said they had encased the magnet in a vacuum. I haven’t heard of it since. I suspect that this technique probably significantly narrowed the bore of the scanner, which would then significantly increase the number one patient complaint about MRI scanners.

I believe noise complaints are a distant second to claustrophobia complaints from patients. (Not to mention that some folks just won’t fit, even if they want to…) The trend in recent years has been to increase bore size whenever possible. Also, there is a constant push to increase gradient strength and slew speed, which adds to the noise.

Today 01:20 PM
johnpost there isn’t the same switching on and off but continuous change.
This sounds like it should help a lot. I wonder what the tradeoff is…

I had an MRI scan a few weeks ago. The staff were making a really big deal beforehand about how loud and unpleasant it was going to be. (Yeah thanks!) As it turned out? Not actually very loud at all, really, with earphones on. Certainly not unpleasantly loud. And a nice comfy bed to lie on for 15 minutes. I could have stayed there quite happily for an hour or two. Probably had a nice nap.

I’m pretty sure this was a bog standard MRI unit, not a quiet one. Is this new reduction in noise meant to be for the benefit of the patient or the staff?

Edit: also I didn’t find it claustrophobic. There was an angled mirror above my face which meant I could see along the length of my body quite easily, and out the end of the tunnel to the booth where the operator was drinking a cup of tea and occasionally pushing buttons.

If you search for “Silenz Sequence” it appears the secret sauce is primarily software-based.

The sound is the gradient coils being driven. In order to get an image you need to drive the field strength at every point in the imaged volume through a range of different strengths, hit the volume with a RF pulse, and record the resulting RF energy. A simple scanner design steps the field, and the steps cause the noise. It would be quite reasonable for a more advanced sequencing to be created, at the cost of more complex recovery of the image.

The basic design assumes a linear ramp of field strength in each dimension, and a 2D fft recovers the image. (That was 20 years ago.) Once the field has non-linear variations it becomes much messier. With modern compute power it is quite reasonable that a more benign profile of field changes could be created, analysed with appropriate changes to the recovery algorithms, and the loudness could be reduced.

Magnetic Resonance imaging involves very complex sequences of magnetic field gradients and radio frequency pulses. The design space is enormous and people are always inventing new sequences with fancy acronyms. These sequences are typically optimized for the best signal to noise ratio, minimum computational requirements and so forth.

GE’s Silenz Sequence is a new pulse sequence that has been optimized in an entirely different way, i. e. to minimize the noise. The claim is that the signal reconstruction is more computationally intensive, but that there is no performance hit in terms of the image quality. This sounds like a brilliant application of the increasing computational power that is affordable. The beauty is that it works on the standard hardware, it is merely a software upgrade.

I would assume the only “catch” is that they cost a million dollars more than the “typical” MRI.

On the consumer side, the problem is that will be many years before enough existing equipment will age out and need replacement before these enhanced machines will be common. In the mean time, there will be a few boutique imaging companies that will offer the service (Similar to the “Open MRI” places seen around). It will be difficult to get appointments to these places, because you may have to pay out of pocket, or there will be long waits for insurance customers.

Good point there. These things endure longer than you might expect. Keep them full of helium and electricity, and they can apparently run for decades.

A few months ago, I was in a mobile MRI, and the main workstation was a Silicon Graphics Indigo, which is a roughly 20 year old Unix box. When my eyes popped out at the sight of the old beast, the tech said “yeah, it’s old, but I think we’re replacing this rig later this year.”

I guess it worked then.

I’ve had 2 MRI’s this year, at different locations. Both times the techs warned me about how loud it was going to be. And my reaction afterwards was “it wasn’t really that loud” – which I think was what they intended. Making the customers more comfortable.

Note that they both offered a wide range of choices for music in the headphones. I;ve now heard that one place is allowing you to bring in your own CD music to listen to, in addition to all their choices. I expect by winter that all the other places will have that option, too.