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1.5T MRI Gradient Slew Rates Compared

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Thumping 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

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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

Make

Model

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/HarmonyTurbo 20 25
Siemens Symphony/HarmonyUltra 20 50
Siemens Symphony/HarmonySprint 30 75
Siemens Symphony/HarmonyQuantum 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 ratecertainly 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