title: Modular MR-compatible lower leg exercise device for whole-body scanners.
abstract: OBJECTIVE
  To develop a modular MR-compatible lower leg exercise device for muscle testing using a clinical 3 T MR scanner.
  
  
  METHODS
  An exercise device to provide isotonic resistance to plantar- or dorsiflexion was constructed from nonferrous materials and designed for easy setup and use in a clinical environment. Validation tests were performed during dynamic MR acquisitions. For this purpose, the device was tested on the posterior lower leg musculature of five subjects during 3 min of exercise at 30% of maximum voluntary plantarflexion during 31-phosphorus MR spectroscopy ((31)P-MRS). Measures of muscle phosphocreatine (PCr), inorganic phosphate (Pi), and pH were obtained before, during, and after the exercise protocol.
  
  
  RESULTS
  At the end of exercise regimen, muscle PCr showed a 28% decrease from resting levels (to 21.8 ± 3.9 from 30.4 ± 3.0 mM) and the average PCr recovery rate was 35.3 ± 8.3 s. Muscle Pi concentrations increased 123% (to 14.6 ± 4.7 from 6.5 ± 3.3 mM) and pH decreased 1.5% (to 7.06 ± 0.14 from 7.17 ± 0.07) from resting levels.
  
  
  CONCLUSIONS
  The described MR-compatible lower leg exercise was an effective tool for data acquisition during dynamic MR acquisitions of the calf muscles. The modular design allows for adaptation to other whole-body MR scanners and incorporation of custom-built mechanical or electronic interfaces and can be used for any MR protocol requiring dynamic evaluation of calf muscles.
authors.affiliation: Musculoskeletal Imaging and Intervention, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, YAW 6048, Boston, MA 02114, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Hosseini Ghomi
authors.forename: Miriam A
authors.initials: MA
authors.lastname: Bredella
authors.forename: Bijoy J
authors.initials: BJ
authors.lastname: Thomas
authors.forename: Karen K
authors.initials: KK
authors.lastname: Miller
authors.forename: Martin
authors.initials: M
authors.lastname: Torriani
mesh_terms: D000328:Adult; D004867:Equipment Design; D015444:Exercise / Q000502:physiology; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*