Sink or swim: Why a hand sink is crucial in the MR suite

Mar 13, 2008

A client of MRI-Planning.com, for whom we had designed an MRI suite nearly six years ago, recently told us how proud he was of a newly initiated breast MR program and the fact that image-guided breast biopsies were now being performed in the suite we helped create.

Back in 2002, breast MR and image-guided biopsy were not reimbursed procedures. In a shortsighted move on the part of everyone involved in planning this facility, we decided that the MRI suite would be strictly diagnostic and would not offer interventional applications.

I asked this client what the hospital's infection control officer had said about performing invasive procedures in the MRI suite. I knew from past experience with this infection control officer that she would disapprove of the biopsy procedures in the MR suite without appropriate provisions for handling blood product.

The client broke eye contact with me and stared sheepishly at the floor before admitting that the in-suite MRI breast program had begun without the knowledge of the infection control officer.

One of the reasons that this suite presented real challenges for breast biopsies was that it didn't include a hand sink. Sinks, which are ubiquitous in nearly every other patient care area in a healthcare setting, are conspicuously absent from most MRI facilities.

When we designed this particular MR suite, we relied on our preconceived notions of what the suite would be used for -- a misguided belief that continues to impair MRI providers' capabilities, even in suites designed more recently.

Stymied by pipes and porcelain

The chief excuse given for not including hand sinks in the MRI room is that installation is technically challenging. But it's difficult to accept that we can site a cryogen-cooled, superconducting magnet that is tens of thousands of times stronger than the earth's own magnetic field, yet are stymied by three pipes and a piece of porcelain!

Let's delve into the technical issues for a moment. MRI scanners are protected from interference through a radiofrequency (RF) shield. A key element of RF shield performance is that it has a single, effective electrical ground, shared with the MRI equipment itself. As everyone who has been ushered out of a swimming pool when a storm blows in knows, water is an excellent conductor of electricity.

So water piping into the MRI suite provides the opportunity for a ground loop. In short, a sink in the MRI suite might cause image problems. However, the same is true for incandescent light bulbs, fingered RF doors, the vendor penetration panels, and a host of other components of standard MRI suite construction. The right plumbing layout can mitigate the risks of image interference.

Pipe placement

Some MRI vendors recommend that you have the piping for the hand sink enter near the penetration panel, in order to tie into the common ground and minimize potential ground-loop issues. The piping should then be routed inside the RF shield enclosure to the final location. Other vendors allow the piping to enter the RF enclosure at the sink location, passing through appropriate dielectric breaks and RF waveguide filters.

Because all plumbing requires periodic maintenance -- and maintenance within MRI suites is often an invitation for disaster -- it's recommended that the plumbing inside the magnet room be minimized, whatever vendor-guidance is taken.

Also, these repairs may require the use of ferromagnetic tools. The hand sink should be located near the magnet room door and in the weakest area of fringe field available inside the room. Meeting this criterion will minimize the amount of time the repairperson spends inside the MR suite and keep them as far as possible from the areas of maximum missile-effect risk.

One strategy is to run the pipes outside the RF enclosure, just behind the location of the sink. Shutoffs and an access panel located outside the MRI room facilitate servicing the sink from an area of low hazard. To enhance the electrical conductivity from the water piping to the RF shield grounding point, electrical conductors can be soldered to the copper pipes, and run between the RF wall and the finished wall from the sink location to the penetration panel grounding point.

Inside the RF shield, copper piping can often give way to PVC piping. Many PVC connectors can be mated by hand, removing the need for ferrous wrenches and other tools.

Whine into water

So to those people who complain that hand sinks are difficult to install -- we say that you're right. Hand sinks inside the MR scanner room are more complicated than regular sink installations elsewhere, and require a level of coordination that even the most experienced plumber maybe not be familiar with.

However, we frequently run plumbing for sprinkler systems and piping for medical gas lines, so pipes for hand sinks can't be deemed impossible.

As with many other safety measures, one of the greatest obstacles to widespread adoption of MR suite hand sinks is a lack of awareness. MRI vendor templates universally fail to show hand sink options. And since many MRI suites wind up as little more than copy-and-paste iterations of the vendor template, hand sinks aren't even considered by the users or their designers.

Given the importance of infection control, it must become a priority. As MR is used for an increasing number of interventional applications, infection control provisions will continue to grow in importance. It is strongly recommended that MR suite providers plan for hand sinks for all future MRI installations.

By Tobias Gilk
AuntMinnie.com contributing writer
March 14, 2008

Reprinted from www.mri-planning.com by permission of the authors. If you would like more information on any aspect of MR facility design or safety, please contact Robert Junk or Tobias Gilk at MRI-Planning.com.

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