Planning MRI suites

The purpose of this post is to share some basic information about MRI units, so you will have an understanding of its principles of operation. It is a crucial role for a medical equipment planner, or anyone responsible for the medical equipment planning of a healthcare project to understand the operation of an MRI unit.

First, the MRI is not an x-ray device. While it is often found in departments called x-ray, radiology, or imaging, it is actually a "listening" device. Much like a video camera can capture an image of a person, the MRI unit captures an image of the body. But instead of light, it uses very faint radio-frequency waves. Here is an excellent video explaining how an MRI works:





MRI stands for magnetic resonance imaging. This is a very accurate acronym for how an MRI works. First, the "M": Magnets are measured by their field strength in tesla. The most common MRI units in US hospitals seem to be 1.5 tesla, but they range from .3 to 3.5 depending upon the application. The "R" resonance, refers to the RF signal emitted by the hydrogen atoms. Finally, "I" is for Imaging. Much more friendly terminology than oto/ophthalmoscope or sphygmomanometer.

So now that you know just enough to be dangerous, let's look at the planning criteria:

1) The room is shielded. Some folks mistakenly think the room is shielded to protect people outside of the room, as is the case with Radiation Therapy and X-ray rooms. The MRI is actually being shielded to ensure an accurate image. The shielding is usually a thin screen of copper. The purpose is to screen OUT any ambient RF signals from other sources. Think of every other electro-magnetic device in the area as offering the potential to create static on the image. The MRI room is shielded to keep out all other RF signals except those being generated by the patients body. This will ensure a clear image.

2) The magnet must be kept cool. Cryogens (Extremely cold liquids) are used to keep the magnet cool. If the magnet ever overheats, the cryogens heat up and expand, creating tremendous pressure. (Same as when a radiator overheats). MRI units are vented to the building exterior in the event the unit overheats, causing the cryogen to do an emergency pressure release. (This is a called a "quench".) The following video is more sensational than educational, but is does show the rapid venting occur. If the unit had been properly installed in the facility, the venting would have been directed safely through duct work to the building exterior. In this instance, it was outside being vented for transport and when it "quenched" it blew the insulation material inside the cabinet everywhere. Very surprising to the folks, but nobody was injured.




3) The magnet is very powerful. While the MRI doesn't produce anything dangerous to humans, the introduction of anything ferrous (Containing iron) is of great concern. Anything small, such as a staple, nail or screw could penetrate the skin of a patient if he or she were between the object and the magnet. Being inside of the MRI tube is certainly a bad place to be if a metal object is being accelerated toward the magnet. Large objects also represent a significant threat. Oxygen cylinders, IV poles, chairs, etc. can cause great harm if slammed into the patient. (See video)



4) The magnet is very heavy. Many range from 12,000 to 20,000 pounds. This means that floors must be reinforced. And not just the room, but also the route they traverse to arrive at the room. Usually a roof hatch or a knock-out wall allows a crane to set the MRI into place. Make sure you do not damage the flooring, or more importantly the building structure if the unit must be rolled into place.

5) Ferrous metal is bad for the image. The magnet field is defined by gauss lines that emanate from the unit in concentric rings. Any movement of a metal object within these fields will affect the image quality. Make sure to study the manufacturers site planning guide and ensure that vehicles (Is the MRI located at an exterior wall?), Elevators (Is the MRI located near an elevator or other vertical transport shaft?) and other moving or transported metal items are outside of the recommended zones.

If you can provide a room that is properly shielded from outside RF "static", provide a hard-ducted vent in the event your MRI should "quench", keep all metal objects out of the room, and, of course, prevent any damage to the floors or structure from its weight, you are freed to focus on the more aesthetic pursuits of lighting, music and patient comfort.

Do you have any suggestions or clarifications? Maybe an interesting picture or video? Please submit your insights and I will supplement this post for others to learn from.

Form following function

It seems on some projects the medical equipment information becomes an important part of the design process only AFTER the floor plan is set. My experience has shown that hiring an equipment planner often becomes a priority when the MEP (mechanical/electrical/plumbing) folks start asking for additional details to complete their late DD or early CD submittal. This is late enough in the design process that the information provided is being used reactively, rather than pro-actively.

Said another way, the design team is plugging the equipment into the room, rather than designing the room around the equipment. I have always been a proponent of form following function. When medical equipment is driving much of the function in a room, it seems prudent for the equipment planner to be available in the initial design sessions. Too often our initial insertion into the project is responding to RFI's in the final push to complete the mechanical, electrical and plumbing specifications.

I'd like to hear your experiences.

Medical Equipment Planning

Welcome.

My objective is to share my knowledge of medical equipment planning and to foster open discussions on topics that relate to the field of medical equipment planning. If you are involved in a healthcare construction project, whether it is a new facility, replacement, expansion or renovation, the equipment planning process will be critical to its success.

Medical equipment planners are sometimes simply called equipment planners, because they plan a more diverse mix of items than just "medical". Kitchen equipment, computers, office machines and just about anything else an architect or interior designer will shrug their shoulders at.

While these other professions will focus on the design, materials, colors and lighting of the interior spaces, about 70% of the infrastructure costs will be driven by what the medical equipment planner does. When planning a fume hood in the lab, it it ducted to the exterior of the building. When planning a surgical light, it receives structural support, electrical and a conduit run to a wall mounted intensity controller. The sterilizer will need steam, water, drain, electrical, data and plenty of ventilation to control the humidity and temperature. So clearly, equipment planning drives much of the detail work on the mechanical, electrical, plumbing, and structural engineering. The better the design teams members understand how items function and their reliance or impact on infrastructure, the more successful the project outcome will be.

I encourage everyone to participate in this blog by passing along any questions they may have or sharing the insights they've gained from past project experience. My aim is to improve the design of healthcare spaces by educating the project team. Hopefully these posts will serve as an easy reference for those who need information, insight, or suggestions. Happy planning!