title: Unsuspected lower extremity deep venous thrombosis simulating musculoskeletal pathology.
abstract: OBJECTIVE
  The purpose of this study was to highlight the critical role that MRI may play in diagnosing unsuspected lower extremity deep venous thrombosis and to stress the importance of scrutinizing MRI studies of the lower extremity showing apparently non-specific muscle edema for any evidence of intramuscular venous thrombosis.
  
  
  METHODS
  The imaging studies of four patients in whom deep venous thrombosis was unsuspected on clinical grounds, and first diagnosed on the basis of MRI findings, were reviewed by two musculoskeletal radiologists in consensus. In all four patients the initial clinical suspicion was within the scope of musculoskeletal injuries (gastrocnemius strain, n=3; ruptured Baker cyst, n=1), explaining the choice of MRI over ultrasound as the first diagnostic modality.
  
  
  RESULTS
  All patients showed marked reactive edema in the surrounding soft tissues or muscles. Three patients showed MR evidence of branching rim-enhancing structures within intramuscular plexuses characteristic of venous thrombosis (gastrocnemius, n=1; sural, n=2); one patient showed a distended popliteal vein. Ultrasound was able to duplicate the MRI findings in three patients: one patient showed above-the-knee extension on ultrasound; neither of the two patients with intramuscular thrombosis demonstrated on ultrasound showed extension to the deep venous trunks.
  
  
  CONCLUSIONS
  Intramuscular venous thrombosis can present as marked edema-like muscle changes on MRI, simulating primary musculoskeletal conditions. In the absence of clinical suspicion for deep venous thrombosis, only the identification of rim-enhancing branching intramuscular tubular structures will allow the correct diagnosis to be made.
authors.affiliation: DII - Diagnostic Imaging, Inc., Department of Radiology, Frankford Hospitals, Torresdale Campus, Red Lion and Knights Roads, Philadelphia, PA 19114, USA. aparellada@diiradiology.com
authors.forename: Antoni J
authors.initials: AJ
authors.lastname: Parellada
authors.forename: William B
authors.initials: WB
authors.lastname: Morrison
authors.forename: Sean B
authors.initials: SB
authors.lastname: Reiter
authors.forename: John A
authors.initials: JA
authors.lastname: Carrino
authors.forename: Peter L
authors.initials: PL
authors.lastname: Glickman
authors.forename: Linda A
authors.initials: LA
authors.lastname: Kloss
authors.forename: Pinecca
authors.initials: P
authors.lastname: Patel
mesh_terms: D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009140:Musculoskeletal Diseases / Q000175:diagnosis; D020246:Venous Thrombosis / Q000175:diagnosis*