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1.5T MRI Gradient Slew Rates Compared

Posted by Steve Rentz

Jul 26, 2019 2:25:00 PM

MRI-Gradient-Slew-RatesThumping along at peak levels of 113 dB (just a couple ticks below a rock concert), MRI gradients are often unnerving and sometimes frightening. If you've ever wondered what it is inside an MRI scanner that makes the loud noise they are known for- gradients are the culprit.

Gradients are actually smaller magnets inside the main MRI magnet. Their job is to modify the magnetic field in the area being scanned so the system can “listen” for the resonance and create an image. It's difficult work to modify a magnetic field strong enough to lift a car (really), so the coils in these smaller magnets move and stress, literally vibrating. These vibrations are the source of the sound. 

In spite of being noisy, they drive MRI value on the secondary market and they come in many varieties. That being said, let's dig a bit deeper so you can:

  1. Be better informed when you are selling your used MRI on the secondary market
  2. Compare gradients across manufacturers when buying a 1.5T MRI

Already have an MRI model in mind? Click here to get a system quote!

MRI Gradient Slew Rate Comparison

The slew rate (AKA "rise time") is the speed at which the gradient reaches its maximum amplitude. Slew rate is measured in millitesla per meter per microsecond (mT/m/ms). The higher the slew rate, the thinner the anatomical slice, which means higher clarity in the image produced. 

Each manufacturer has three or four different gradients and they all have interesting names (see the table below). Because of this, the easiest way to keep your gradient packages straight is by comparing the slew rate.

Major OEM Gradients and Slew Rates 



Amplitude (mT/m)  

Slew Rate (mT/m/ms)

GE HiSpeed 23 (33 for Plus) 77
GE EchoSpeed 23 (33 for Plus) 120
GE  HD 33  120 
GE HDXT  33  120 
GE HDe 33  50 
GE Optima 450 34  150 
GE Optima 450w 34  150 
Siemens  Symphony/Harmony Turbo 20 25
Siemens  Symphony/Harmony Ultra   20   50 
Siemens  Symphony/Harmony Sprint   30   75 
Siemens Symphony/Harmony Quantum   30   150 
Siemens Avanto Q-Engine  33  125 
Siemens Avanto SQ-Engine  45  200 
Siemens Espree Q-Engine  33  125 
Siemens Espree SQ-Engine  45  200 
Siemens Aera XJ   33   125 
Siemens Aera XQ  45  200 
Philips  Power   30  75 
Philips  Master   30   150 
Philips  Pulsar   33  80 
Philips  Nova   33   160 
Philips Ingenia   45   200 
Toshiba  Excelart AG   30   50 
Toshiba  Vantage AGV   30   50 
Toshiba  Vantage XGV   30   130 


The Takeaway

Many first-time buyers are under the impression that they should get the system with the highest slew rate possible. To them we say: It's a nice thing to have, but you have to be willing to pay more for it. A higher slew rate certainly enhances the marketability of your MRI on the secondary market, but the initial cost of the machine will be significantly higher. Ultimately, the slew rate that is absolutely necessary for you to have will depend on the types of studies you intend to do on a routine basis. 

If you'd like more information or a consult on which MRI scanner slew rate might be the best for the work you plan to do, our team is ready to help. Give us a call, or check out our free MRI Buyer's Guide to learn more.

MRI Buyer's Guide

Topics: Buying Imaging Equipment, Selling Imaging Equipment, MRI

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