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UMass Researchers Invent MRI-compatible Ergometer to Study Human Muscle Function

Frank Sup

Frank Sup

Ergometer

Ergometer

Professor Frank Sup of the Mechanical and Industrial Engineering (MIE) Department is collaborating with Professor Jane Kent of the Kinesiology Department on a groundbreaking non-magnetic ergometer, which can be used in conjunction with a magnetic resonance (MR) machine to conduct pioneering MR imaging and spectroscopy studies of human muscle function.

The collaboration was formed within the Center for Personalized Health Monitoring at the Institute for Applied Life Sciences (IALS), a new organization within UMass Amherst that aims to translate fundamental discoveries on campus into novel candidate medical devices, biomolecules, and delivery vehicles that benefit human health.

The group of researchers will use the new ergometer to investigate the energetic mechanisms underpinning changes in muscle function, which can yield unique insights into mobility impairments with age. “It is essentially a precision, instrumented piece of exercise equipment that can work inside of a large magnet, or MRI,” said Sup.

According to Kent, “the device advances existing capabilities in that it is the first of its kind capable of quantifying human muscle force and power using three different modes of contraction while the person exercises in the bore of the MRI machine.”

In addition to Sup and Kent, the researchers involved in the study are Sup’s MIE M.S. student Youssef Jaber, as well as Kent’s doctoral students Miles Bartlett and Liam Fitzgerald in the Department of Kinesiology.

Kent’s Muscle Physiology Laboratory has been working on a project to study the biochemical and physical dynamics of the lower limb when working near its physical limits and are thus pursuing new knowledge about how aging or chronic disease affect human muscle function. To perform this sort of research, the Muscle Physiology Laboratory needed a customized non-magnetic ergometer capable of controlling muscle contraction velocity and operating compatibly with an MR machine.

Using magnetic resonance spectroscopy enables accurate, noninvasive measurements of the metabolic energy requirements of active muscles. However, for such a technique to be used on an exercising muscle, a magnetic-resonance-compatible exercise apparatus targeting those muscles needed to be created.

To develop such an ergometer, Kent asked Sup’s Mechatronics and Robotics Research Laboratory to develop an innovative and robust design.

Jaber explained that a magnetic-resonance-compatible design must account for the presence of the strong electromagnetic fields generated by the MRI scanner. That includes both the effect of the field on the device to be designed in terms of safety and functionality, and the effect of the designed device on the field, which can lower the scanning quality. This electromagnetic relationship is called “mutual interference,” and the purpose of magnetic-resonance-compatible design is to limit such interference to a point in which the device achieves the desired performance safely without greatly affecting the scanning quality.

“The goal of this project is to design a magnetic-resonance-compatible ergometer capable of applying controlled resistive loads on the lower limb and enabling the study of its tissue while the muscles are working under various conditions,” explained Jaber. “The loads will be controlled by the device’s motor to allow for isotonic, isometric, and isokinetic contractions.”  

Kent added that “This piece of equipment will allow precise, noninvasive quantitation of muscle bioenergetics, which can be tracked in the same individual over the course of disease progression, during aging, or in response to therapeutic interventions.”

The resulting design achieves magnetic-resonance-compatibility by locating all of the powered and sensing elements away from the MRI field and placing them in an adjacent room. Those elements are connected mechanically through a system of wires and pulleys to passive components inside the MR scanner. This setup removes many of the impacts of the magnetic fields on actuator and sensor selection.

Sup is the head of the Mechatronics and Robotics Research Laboratory, which focuses on the advancement of physical human-machine interaction. The core of the lab’s research is on human-centered mechatronic design in the development of rehabilitative technologies. The research topics span from wearable robotics, such as intelligent prosthetics and exoskeletons, to advanced control structures and methodologies.

Kent is the director of the Muscle Physiology Laboratory and the interim director of the new Human Magnetic Resonance Center at UMass, which houses the MR system these researchers are using. Professor Kent’s lab has been at the forefront of studying age-related declines in skeletal muscle function and mobility for the past 20 years. The lab’s goals are to understand how neuromuscular structure and function support mobility-related health, and how mobility can be maintained in the face of aging or morbidity.

IALS is advancing the UMass educational and economic development missions by training researchers skilled in the discovery, development, and manufacture of medical devices and biomolecules and in life science entrepreneurship. (February 2017)