special MRI techs

voltatab · Joined: 09 Jul 2007 Posts: 1

hello,
i had a friend who told me about specific MRI techs who only operate on older machines...ones that newer MRI techs dont work on because they dont have the proper training for it.
Is this true? Are there MRI techs who have special training on only certian types of older models?If so, what school would you go to, to learn about it? I would appreciate any information on how to be specially trained in the early models so that i can be a specialist with certian models. thanks

MagnetMan · Joined: 05 Jan 2007 Posts: 22 Location: Belpre, Oh

An MRI tech is an MRI Tech. I am a Registered ARRT MRI Tech and I can do any MRI on any MRI machine with some light training. Alot of places cross train X-Ray Techs to do MRI. Anyone can train to do MRI and there is no machine that any MRI Tech cannot do without training. I was trained on a GE and currently work on an Hitachi. I can do Siemens and Toshiba with a day or two of getting use to the system itself. MRI exams are the same at all facilities as far as anatomy and sequence selection. Its just like driving different makes of cars, you can drive a toyota everyday and use the windshield wipers and light, but get into a ford and you have to know where the controls are located and to familiarize yourself with the change of scenery.

creber · Joined: 09 Apr 2008 Posts: 2

hello, MagnetMan. I met a problem on GE and hope you can show me the method to get phase images and magnitude images, instead of common images, after scanning. The scanner is a GE 1.5T Signa Excite.

MagnetMan · Joined: 05 Jan 2007 Posts: 22 Location: Belpre, Oh

Magnitude images are most common in MRI because they avoid the problem of phase artifacts by deliberately discarding the phase information. The signal is measured through a quadrature detector that gives the real and the imaginary signals. We will assume the noise in each signal to have a Gaussian distribution with zero mean and each channel will be assumed to be contaminated with white noise.

The magnitude images are formed by calculating the magnitude, pixel by pixel, from the real and the imaginary images. This is a nonlinear mapping and therefore the noise distribution is no longer Gaussian.

Phase images, which are commonly used in flow imaging, are reconstructed from the real and the imaginary images by calculating pixel by pixel the arctangent of their ratio. This is a nonlinear function and therefore we no longer expect the noise distribution to be Gaussian.
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Chief MRI Technologist, Radiation Safety Officer, ACR Coordinator. Proficient on GE and Hitachi MRI Scanners.

creber · Joined: 09 Apr 2008 Posts: 2

Thank you for the introduction. Is there any direct methods to acquire phase/magnitude images or real/imaginery images after scanning? I mean, maybe there is an opition somewhere I should check before scanning, so I will get phase/magnitude images or real/imaginery images. For example, to a GRE sequence, how should I set up the parameters in a GE 1.5T scanner?

Thanks again.