An Ohio State University (OSU) Medical Center research team has designed equipment to enable exercise-based stress testing with MR imaging, enabling the acquisition of high-resolution cardiac images without pharmacologically-induced stress.
The images are obtained with a test lasting less than one hour, according to the researchers.
“In the past, we were constrained by the time lapse between the completion of exercise and capturing the images,” said Orlando Simonetti, PhD, associate professor of internal medicine and radiology at OSU. “We now have the ability to exercise patients to peak stress and obtain a high-definition image of their heart within 60 seconds, which helps us more accurately identify exercise-induced abnormalities.” He added that OSU Medical Center is the only place performing treadmill exercise stress tests inside the MRI scan room.
The design of treadmills has made exercise stress testing a challenge near the large magnetic field generated by the MRI equipment, according to the researchers. Simonetti and his team, working with graduate students from Ohio State’s College of Engineering and faculty from the OSU Agricultural Technical Institute, said they modified a treadmill for use in close proximity to the MRI exam table. Magnetic components were replaced with non-magnetic stainless steel and aluminum equivalents.
While patients perform the treadmill exercise test, they are monitored using a 12-lead electrocardiogram system that is disconnected after exercise, Simonetti and colleagues said. Heart rate and rhythm are then monitored with a wireless, MRI-compatible electrode unit, while patients undergo an imaging procedure that takes less than one minute.
“While current forms of stress testing have been helpful, combining exercise stress with cardiac MRI allows us to better measure the presence and extent of heart disease with a clarity not previously possible,” said Subha Raman, MD, associate professor of internal medicine in OSU Medical Center’s division of cardiovascular medicine.