title: Real-time magnetic resonance imaging (MRI) during active wrist motion--initial observations.
abstract: BACKGROUND
  Non-invasive imaging techniques such as magnetic resonance imaging (MRI) provide the ability to evaluate the complex anatomy of bone and soft tissues of the wrist without the use of ionizing radiation. Dynamic instability of wrist--occurring during joint motion--is a complex condition that has assumed increased importance in musculoskeletal medicine. The objective of this study was to develop an MRI protocol for evaluating the wrist during continuous active motion, to show that dynamic imaging of the wrist is realizable, and to demonstrate that the resulting anatomical images enable the measurement of metrics commonly evaluated for dynamic wrist instability.
  
  
  METHODS
  A 3-Tesla "active-MRI" protocol was developed using a bSSFP sequence with 475 ms temporal resolution for continuous imaging of the moving wrist. Fifteen wrists of 10 asymptomatic volunteers were scanned during active supination/pronation, radial/ulnar deviation, "clenched-fist", and volarflexion/dorsiflexion maneuvers. Two physicians evaluated distal radioulnar joint (DRUJ) congruity, extensor carpi ulnaris (ECU) tendon translation, the scapholunate (SL) interval, and the SL, radiolunate (RL) and capitolunate (CL) angles from the resulting images.
  
  
  RESULTS
  The mean DRUJ subluxation ratio was 0.04 in supination, 0.10 in neutral, and 0.14 in pronation. The ECU tendon was subluxated or translated out of its groove in 3 wrists in pronation, 9 wrists in neutral, and 11 wrists in supination. The mean SL interval was 1.43 mm for neutral, ulnar deviation, radial deviation positions, and increased to 1.64 mm during the clenched-fist maneuver. Measurement of SL, RL and CL angles in neutral and dorsiflexion was also accomplished.
  
  
  CONCLUSIONS
  This study demonstrates the initial performance of active-MRI, which may be useful in the investigation of dynamic wrist instability in vivo.
authors.affiliation: Department of Radiology, University of California Davis School of Medicine, Sacramento, California, United States of America.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Boutin
authors.affiliation: Department of Radiology, University of California Davis School of Medicine, Sacramento, California, United States of America ; University of California Davis Imaging Research Center, Sacramento, California, United States of America.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Buonocore
authors.affiliation: Department of Orthopedic Surgery, University of California Davis School of Medicine, Sacramento, California, United States of America.
authors.forename: Igor
authors.initials: I
authors.lastname: Immerman
authors.affiliation: Department of Radiology, University of California Davis School of Medicine, Sacramento, California, United States of America.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Ashwell
authors.affiliation: Department of Orthopedic Surgery, University of California Davis School of Medicine, Sacramento, California, United States of America.
authors.forename: Gerald J
authors.initials: GJ
authors.lastname: Sonico
authors.affiliation: Department of Orthopedic Surgery, University of California Davis School of Medicine, Sacramento, California, United States of America.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Szabo
authors.affiliation: Department of Radiology, University of California Davis School of Medicine, Sacramento, California, United States of America.
authors.forename: Abhijit J
authors.initials: AJ
authors.lastname: Chaudhari
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007593:Joint Instability / Q000517:prevention & control; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D011403:Pronation / Q000502:physiology*; D011446:Prospective Studies; D013484:Supination / Q000502:physiology*; D014953:Wrist / Q000502:physiology*; D014955:Wrist Joint / Q000502:physiology*