Researchers at the University of Massachusetts Amherst have developed an advancedtype of ergometer which can be used inside the strong magnetic fields of a magnetic resonance imaging (MRI) machine to study how human muscles function.
The research team is headed by Frank C. Sup, assistant professor of mechanical and industrial engineering, and Jane A. Kent, professor of kinesiology. They will use the new ergometer, a device that measures muscle power, to investigate the energetic mechanisms for changes in muscle function in old age and chronic disease, which can yield 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,” says Sup.
Kent says, “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.” Previous systems typically had capabilities for only one or two of these modes, she says.
The project is a collaboration within the Institute for Applied Life Sciences’ Center for Personalized Health Monitoring, a UMass Amherst research center designed to translate fundamental discoveries into novel medical devices, biomolecules, and delivery vehicles that benefit human health. The work is being done on the new, high-field imaging system in the Human Magnetic Resonance Center. This system is capable of obtaining both MR imaging (MRI) and spectroscopy (MRS) data on essentially any body tissue.
Kent’s Muscle Physiology Laboratory has been working ona project to study thigh muscle energetics when working near its physical limits and are thus pursuing new knowledge about how aging or chronic disease affect human muscle function and fatigue.To perform this sort of research, the researchers needed a customized non-magnetic ergometer capable of controlling muscle contraction velocity and operating 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.
Kent contacted Sup’s Mechatronics and Robotics Research Laboratory to develop such a device. Youssef Jaber, one of Sup’s graduate students, says a magnetic-resonance-compatible design must account for the presence of the strong electromagnetic fields generated by the MR scanner. That includes both the effect of the magnetic field on the device in terms of safety and functionality, and the effect of the device on the magnetic field itself, which can lower scan quality. This electromagnetic relationship is called “mutual interference,” Jaber says.
“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.
Kent says, “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 MRI scanner. This setup removes many of the impacts of the magnetic fields on actuator and sensor selection.