Guest opinion courtesy of Daniel R. Baker, Ph.D., CPE
At the recent meeting of the North American Spine Society (NASS), a new magnetic resonance imaging (MRI) was one of the highlights. But what’s so different about a new MRI? This one considers human factors and ergonomics, both for the patient and for the doctor. But the most exciting aspect of the new MRI may be its potential for the ergonomist.
MRIs provide three-dimensional views inside the body; for the viewer, an MRI image can highlight specific tissues, fluids, muscle groups or almost anything that the viewer desires. Until now, MRI scanners required patients to lie down and be placed in a long narrow closed tube. Unfortunately, when only a horizontal position is available for viewing, MRIs don’t serve too much of purpose for the ergonomist. But a company named FONAR (Mellville, NY, www.fonar.com) may be changing this with its “upright” MRI system.
For the ergonomist, many of the current models of how various body parts get loaded (during lifting or sitting, for example) are based on horizontal imaging, cadaveric work and some logical assumptions about how the body adjusts to various body configurations. Three-dimensional imaging of live humans in various positions or while performing similar work tasks could offer a great means to validate and improve the current biomechanical models.
For instance, when designing a new tool, product or task, an ergonomist with a three-dimensional view of a person using the tool (chair, drill, hammer) or performing a task (lifting) can actually get a look inside the body of the person to see how the tissues or the spine are aligned while performing the task. Ultimately, the ergonomist could then see the impact and, if necessary, modify the design. Horizontal MRIs don’t offer this subject flexibility.
Specifically, the new scanner allows placement of the subject, be it a worker, model or patient, in many different positions. This is accomplished by changing the magnet configurations on the MRI so there is an open gap where the subject is positioned. The subject positioning table not only slides horizontally in and out of the field as in conventional MRIs but it also rotates to afford a standing position, or it can be modified to accommodate various seated positions.
Another bonus to designers is the size of the subject that can be scanned. Tube models typically limit patient size to approximately 350 pounds. The FONAR MRI can accommodate a subject up to 650 pounds.
And aside from the ergonomics ramifications of an MRI that allows a subject to take on almost any feasible position, there are additional ergonomics benefits for other users of the FONAR MRI as well. Medical MRI operators and doctors who interpret and use the images may find that, in diagnosing musculoskeletal problems and other conditions that aren’t overtly apparent on a horizontal MRI, having a patient in a non-horizontal position is beneficial. For the subject of the MRI, being placed in the quieter FONAR model rather than older MRI models with their knocks, pings, clangs and pops may make a somewhat stressful situation more relaxing. Plus, putting the patient through a less claustrophobic imaging process increases the patient comfort and reduces extraneous movements and stress. And, as an additional distraction against unwanted movements, a large screen television is provided in the patient’s field of view.
FONAR representatives at NASS indicated that presently over 20 of these MRIs have been installed throughout the United States, but to date, none are known to be in use for ergonomic or biomechanical evaluations. Perhaps it will not be long until they are.
About the author:
Daniel R. Baker, Ph.D., CPE (firstname.lastname@example.org) runs a Seattle-based medical device development company that specializes in implants and instrumentation. He also teaches a course on human factors in medical product design at the University of Washington. He has no ties to FONAR.