5 ms·

MRI operator here: the false alarms from all the metal that’s fine are an issue. Most people have some in/on them and it’s usually fine.

int_19h 1y ago
Given the rather spectacular failure mode, isn't this rather a case of "better safe than sorry"? i.e. even if it's technically safe, why not require people to remove everything that triggers the detector just to be sure?
- lostlogin 1y ago
  You’d be surprised what people won’t do. Unlike many facilities, we insist everyone strips down to underpants (no bra) and wears a gown. We push quite hard to remove all jewellery (including piercings), but many places do not. It removes a whole category of problems, but is also slow, has an extra cost (laundry) and still patients leave things on, covered up by the gown. But the percentage of people with something in them is very very high. We are dealing with a population that by definition has health issues, and I’d estimate that 75%+ have something metal in them. Sternal wires, fillings, clips, biopsy markers, screws, plates, braces, joint replacements (x6), ports, mesh, vascular stent, urinary stents, breast implants. These are conditionally safe implants from yesterday. If we expanded it to a week we could add heart valves, hearing implants, vsd closure devices and about 20 other implants I’m sure. We have either memorised or looked up the conditions for each. We pay techs well because we want good staff. Minimum staffing levels include using healthcare assistants and suchlike. There are potential downsides to this approach, particularly around safety.
  - userbinator 1y ago
    and still patients leave things on, covered up by the gown A strong but still relatively weak "test magnet" seems like it might be a good idea to use on patients --- if it has any effect on any metal pieces they're wearing, tell them the MRI is going to pull on it with a thousand times or more force.
    - lostlogin 1y ago
      We have a handheld one for this. Some piercings really won't come out. The set of pliers, tweezers and the enthusiastic radiographer can't manage it.
xrcyz 1y ago
What distinguishes fine from not fine? During COVID a tech asked me to get in the MRI machine wearing a face mask with a metal wire across the nose. They seemed exasperated when I refused.
- aaronmdjones 1y ago
  Ferromagnetism. A 24-carat gold necklace would not be sucked into the machine for example, while a 7-carat gold necklace would (that contains steel, which contains iron). However, any kind of metal can be less dangerous for other reasons. For example, (pure, 24 Ct) gold, while not ferromagnetic, is an electrical conductor (like almost all metals), and so will heat up with the eddy currents passing through it. This could cause burn injuries if you are wearing it.
- lostlogin 1y ago
  wise - some face masks become projectiles and are a risk to eyes. This was tested during covid. Some masks are ok. Some also have ferrous staples that attach the elastic straps, and these are also a problem.

int_19h 1y ago

Given the rather spectacular failure mode, isn't this rather a case of "better safe than sorry"? i.e. even if it's technically safe, why not require people to remove everything that triggers the detector just to be sure?

lostlogin 1y ago
You’d be surprised what people won’t do. Unlike many facilities, we insist everyone strips down to underpants (no bra) and wears a gown. We push quite hard to remove all jewellery (including piercings), but many places do not. It removes a whole category of problems, but is also slow, has an extra cost (laundry) and still patients leave things on, covered up by the gown. But the percentage of people with something in them is very very high. We are dealing with a population that by definition has health issues, and I’d estimate that 75%+ have something metal in them. Sternal wires, fillings, clips, biopsy markers, screws, plates, braces, joint replacements (x6), ports, mesh, vascular stent, urinary stents, breast implants. These are conditionally safe implants from yesterday. If we expanded it to a week we could add heart valves, hearing implants, vsd closure devices and about 20 other implants I’m sure. We have either memorised or looked up the conditions for each. We pay techs well because we want good staff. Minimum staffing levels include using healthcare assistants and suchlike. There are potential downsides to this approach, particularly around safety.
- userbinator 1y ago
  and still patients leave things on, covered up by the gown A strong but still relatively weak "test magnet" seems like it might be a good idea to use on patients --- if it has any effect on any metal pieces they're wearing, tell them the MRI is going to pull on it with a thousand times or more force.
  - lostlogin 1y ago
    We have a handheld one for this. Some piercings really won't come out. The set of pliers, tweezers and the enthusiastic radiographer can't manage it.

xrcyz 1y ago

What distinguishes fine from not fine? During COVID a tech asked me to get in the MRI machine wearing a face mask with a metal wire across the nose. They seemed exasperated when I refused.

aaronmdjones 1y ago
Ferromagnetism. A 24-carat gold necklace would not be sucked into the machine for example, while a 7-carat gold necklace would (that contains steel, which contains iron). However, any kind of metal can be less dangerous for other reasons. For example, (pure, 24 Ct) gold, while not ferromagnetic, is an electrical conductor (like almost all metals), and so will heat up with the eddy currents passing through it. This could cause burn injuries if you are wearing it.
lostlogin 1y ago
wise - some face masks become projectiles and are a risk to eyes. This was tested during covid. Some masks are ok. Some also have ferrous staples that attach the elastic straps, and these are also a problem.