title: Incidental signal changes in the extensor carpi ulnaris on MRI.
abstract: BACKGROUND
  Magnetic resonance imaging (MRI) commonly finds musculoskeletal abnormalities incidental to the reason for ordering the test. The purpose of this study was to determine if the prevalence of extensor carpi ulnaris (ECU) signal changes on MRI varies between patients undergoing upper extremity MRI for assessment of clinically suspected ECU tendinopathy and those undergoing upper extremity MRI for other indications. Our secondary null hypotheses were that the prevalence of ECU signal changes on MRI does not vary based on patient age or sex and that the prevalence of ECU signal changes on MRI does not vary among other indications for MRI.
  
  
  METHODS
  We searched MRI reports of all patients undergoing MRI of the hand, wrist, or arm at our institution between 2001 and 2014 for signal changes in the ECU. The medical record was reviewed to determine the indication for the MRI and the presence of clinically suspected ECU tendinopathy.
  
  
  RESULTS
  ECU signal changes (overall prevalence of 13 %) were more common in patients undergoing MRI for a working clinical diagnosis of ECU tendinopathy or ulnar-sided wrist pain compared to patients evaluated for nonspecific pain and other indications. Age was independently associated with ECU signal changes on MRI. MRI signal changes are uncommonly associated with symptomatic tendinopathy (low positive predictive value).
  
  
  CONCLUSIONS
  ECU signal changes on MRI are common and often asymptomatic.
authors.affiliation: Orthopaedic Hand and Upper Extremity Service, Yawkey Center, Massachusetts General Hospital, Suite 2100, 55 Fruit St, Boston, MA 02114 USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Kuntz
authors.affiliation: Orthopaedic Hand and Upper Extremity Service, Yawkey Center, Massachusetts General Hospital, Suite 2100, 55 Fruit St, Boston, MA 02114 USA.
authors.forename: Stein J
authors.initials: SJ
authors.lastname: Janssen
authors.affiliation: Orthopaedic Hand and Upper Extremity Service, Yawkey Center, Massachusetts General Hospital, Suite 2100, 55 Fruit St, Boston, MA 02114 USA.
authors.forename: David
authors.initials: D
authors.lastname: Ring
keywords: Extensor carpi ulnaris; Incidental findings; Magnetic resonance imaging; Signal changes; Tendinopathy