MRI - Well that was an experience.....

[fossyant]

Well, needles and electodes stuck into me in two weeks time for Electromyography and Nerve Conduction Tests - funking car drivers......

Anyone an expert on these ? - should have asked Mags before I had the MRI - knew he played with them.......

 

[magnatom]

Well, needles and electodes stuck into me in two weeks time for Electromyography and Nerve Conduction Tests - funking car drivers......

Anyone an expert on these ? - should have asked Mags before I had the MRI - knew he played with them.......

I'm don't know much about these, but a chap down the corridor does!

Actually my mother had this done to test for her MND (did I mention I was doing a 100 mile ride for charity). My mother didn't have any problems, so I'm sure you'll be fine.

 

[ufkacbln]

CAT or Computerise Axial Tomography Scanners use a rotating beam of xrays that pass through the body in thesame way as an ordinary xray. The computer then uses this data to build a 3D image of the body that can be "sliced" into th cross sectional images we are so familiar with.

The PET or Positron Emission Tomography Scanner is a ring of detectors that detects radiation. Instead of being produced by the machine it is injected (usually in the form of "FDG") in a glucose like substance that is taken up by the body. Flourine 18 emits a small unstable positron that meets an electron and annihalates itself into two high energy particles that are detected and make up the image. Again the data is recondtruccted into a 3D model that can be sliced. Typically tumours are hungry and take up lots of glucose and hence show up. Typically scans take 30 - 40 minutes.

What you have missed out so far is SPECT Single Photon Emission Computerised Tomography where a radioactive tracer is labelled to go to a certain organ. The activity is detected by two rotating heads that again allow a 3d image to be built.

The SPECT and PET are brilliant in showing the way an organ works, but bad at showing detailed anatomy. It is common now to combine PET or SPECT with CT to get fused images that show both.

The amount of radiation dose varies and each method contributes differently to diagnosis.

I am a radiographer and am at present installing a SPECT CT and PET CT in our new department!

I got one of these:

.....and one of these arriving shortly!

 

[Cathryn]

This is a surprisingly interesting thread.

Forgive my ignorance but why can't you have an MRI with metal in your leg, for example?

 

[Black Sheep]

This is a surprisingly interesting thread.

Forgive my ignorance but why can't you have an MRI with metal in your leg, for example?

because of the strength of the magnet in the MRI scanner

if for example you had a metal in you thats magnetic you'd get stuck to the wall of the scanner, perhaps.

 

[Cathryn]

Oooh...nasty. Thanks for explaining.

 

[magnatom]

Thanks Cunobelin. I have a dedicated head SPECT scanner around the corner from my office. Hopefully I benifit from the positive effect of small amounts of radiation (true) !

Cathryn,

You almost always can have an MRI with metal in your leg. I know this for a fact as I have two metal pins in my leg and have had numerous MRI scans!

It's not as simple as completely excluding all metal. For example the pins in my leg are not ferromagnetic (attracted to magnets) and so will not move in the scanner. They are also firmly attached to my leg. This adds to their 'weight', i.e. it would take greater force to move the pins and my legs (and body) so the more weight a metal is attatched stronlgy to, the less likely it will be able to move.

A complication comes from the fact that metals that can conduct electricity can be a problem. The radiofrequency waves that we pulse in, can induce currents in such metals. However, this depends on the length of the metal, where it is in the magnet, what the magnet field strength is, etc. In general the longer the metal the worse it is.

It's quite a complicated business, luckily for me. That's why physicists are needed! B)

 

[magnatom]

I should also add, and I am sure Cunobelin would agree, that CT, MRI, SPECT, PET etc are more often than not, complimentary. They rarely look at the same things, so despite what people think we don't compete against each other.B)

 

[papercorn2000]

Which hospital do you work in?

My friend is a senior Radiographer at the Southern. You may know her.

 

[magnatom]

Which hospital do you work in?

My friend is a senior Radiographer at the Southern. You may know her.

I might well know her. I'm at the neurological scanner.

 

[papercorn2000]

This is a surprisingly interesting thread.

Forgive my ignorance but why can't you have an MRI with metal in your leg, for example?

There was an episode of Messiah where one guy - with a metal plate or some such stuck in his head - was killed by being put in an MRI. The magnets ripped his head apart.

Would that happen?

 

[papercorn2000]

I might well know her. I'm at the neurological scanner.

Her names Kirsty, she's married to the guy who was my best man! He was, incidentally featured in the 'injuries' section of last month's MBR!

 

[magnatom]

There was an episode of Messiah where one guy - with a metal plate or some such stuck in his head - was killed by being put in an MRI. The magnets ripped his head apart.

Would that happen?

B) No. He could be pulled into the magnet with some force, although even this would be unlikely. Most implants these days are not ferromagnetic. However, you certainly wouldn't wan't to scan someone with a metal plate in their head. It could heat and and cause burns, or more likely, it will cause significant problems with the images, i.e. it would appear that there is a huge hole in his head (which isn't really there).

 

[magnatom]

Her names Kirsty, she's married to the guy who was my best man! He was, incidentally featured in the 'injuries' section of last month's MBR!

I think I might know her (she isn't always in MR is she? sometimes CT?)

Next time I see her, I'll ask her if her husband is into mountain biking!B)

 

[papercorn2000]

She does all kinds of scanning stuff, so I wouldn't know. It was her birthday on Tuesday y'know.

It's a small world - but you wouldn't really want to cut all the grass.