title: Low Cost Magnetic Resonance Imaging-Compatible Stepper Exercise Device for Use in Cardiac Stress Tests.
abstract: Cardiovascular disease is the leading cause of death worldwide. Many cardiovascular diseases are better diagnosed during a cardiac stress test. Current approaches include either exercise or pharmacological stress echocardiography and pharmacological stress magnetic resonance imaging (MRI). MRI is the most accurate noninvasive method of assessing cardiac function. Currently there are very few exercise devices that allow collection of cardiovascular MRI data during exercise. We developed a low-cost exercise device that utilizes adjustable weight resistance and is compatible with magnetic resonance (MR) imaging. It is equipped with electronics that measure power output. Our device allows subjects to exercise with a leg-stepping motion while their torso is in the MR imager. The device is easy to mount on the MRI table and can be adjusted for different body sizes. Pilot tests were conducted with 5 healthy subjects (3 male and 2 female, 29.2 ± 3.9 yr old) showing significant exercise-induced changes in heart rate (+42%), cardiac output (+40%) and mean pulmonary artery (PA) flow (+%49) post exercise. These data demonstrate that our MR compatible stepper exercise device successfully generated a hemodynamically stressed state while allowing for high quality imaging. The adjustable weight resistance allows exercise stress testing of subjects with variable exercise capacities. This low-cost device has the potential to be used in a variety of pathologies that require a cardiac stress test for diagnosis and assessment of disease progression.
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison , Engineering Centers Building, 1550 Engineering Drive, Madison, WI 53706 e-mail:  forouzan@wisc.edu.
authors.forename: Omid
authors.initials: O
authors.lastname: Forouzan
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison , Engineering Centers Building, 1550 Engineering Drive, Madison, WI 53706 e-mail:  ewflink@gmail.com.
authors.forename: Evan
authors.initials: E
authors.lastname: Flink
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison , Engineering Centers Building, 1550 Engineering Drive, Madison, WI 53706 e-mail:  jaredwarczytowa@gmail.com.
authors.forename: Jared
authors.initials: J
authors.lastname: Warczytowa
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison , Engineering Centers Building, 1550 Engineering Drive, Madison, WI 53706 e-mail:  nthate@gmail.com.
authors.forename: Nick
authors.initials: N
authors.lastname: Thate
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison , Engineering Centers Building, 1550 Engineering Drive, Madison, WI 53706 e-mail:  ahanske@epic.com.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hanske
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison , Engineering Centers Building, 1550 Engineering Drive, Madison, WI 53706 e-mail:  leto@seas.upenn.edu.
authors.forename: Tongkeun
authors.initials: T
authors.lastname: Lee
authors.affiliation: Department of Medical Physics, Wisconsin Institutes for Medical Research , 1111 Highland Avenue, Madison, WI 53705-2275 ;
authors.forename: Alejandro
authors.initials: A
authors.lastname: Roldan-Alzate
authors.affiliation: Department of Radiology, University of Wisconsin , School of Medicine and Public Health, E3/366 Clinical Science Center, 600 Highland Avenue, Madison, WI 53792-3252 e-mail:  cfrancois@uwhealth.org.
authors.forename: Chris
authors.initials: C
authors.lastname: François
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison , Engineering Centers Building, 1550 Engineering Drive, Madison, WI 53706 ;
authors.forename: Oliver
authors.initials: O
authors.lastname: Wieben
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison , Engineering Centers Building, 1550 Engineering Drive, Madison, WI 53706 e-mail:  chesler@engr.wisc.edu.
authors.forename: Naomi C
authors.initials: NC
authors.lastname: Chesler