title: Utility of balanced steady-state free precession MR venography in the diagnosis of lower extremity deep venous thrombosis.
abstract: OBJECTIVE
  The purpose of this study was to determine the sensitivity and specificity of balanced steady-state free precession MR venography in the diagnosis of lower extremity deep venous thrombosis.
  
  
  METHODS
  After undergoing lower extremity ultrasound because of suspicion of deep venous thrombosis, 64 patients were prospectively recruited to undergo balanced steady-state free precession MR venography with ultrasound as the reference standard. Ultrasound images were independently interpreted by two blinded ultrasound radiologists, and MR venograms were independently interpreted by two blinded MRI radiologists. The sensitivity, specificity, positive predictive value, and negative predictive value of MR venography were calculated for the diagnoses of all deep venous thrombosis, acute thrombi, and thrombosis of the popliteal, femoral, and common femoral veins individually. Proximal extent, thrombus age, ancillary findings, and interobserver agreement calculated with the Cohen kappa test were evaluated for ultrasound and MRI. The McNemar test was used to evaluate for statistical differences in diagnostic accuracy.
  
  
  RESULTS
  MR venography had a sensitivity of 94.7%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 97.7% for the diagnosis of all thrombi. For acute thrombi, the MR venography and ultrasound results were completely concordant. MR venography depicted greater proximal extent in five of 18 cases in which thrombosis was found. The MR venographic findings agreed completely with the ultrasound findings in determination of thrombus age. For both ultrasound and MR venography, interobserver agreement was 100% on a per-patient basis. No statistical difference was identified in the diagnostic performance of the two techniques.
  
  
  CONCLUSIONS
  Balanced steady-state free precession MR venography is highly accurate in the diagnosis of lower extremity deep venous thrombosis.
authors.affiliation: Faculty of Medicine, University of Manitoba, 727 McDermot Ave, Winnipeg, MB R3P 1X1, Canada. umlindqu@cc.umanitoba.ca
authors.forename: Chris M
authors.initials: CM
authors.lastname: Lindquist
authors.forename: Fern
authors.initials: F
authors.lastname: Karlicki
authors.forename: Patrick
authors.initials: P
authors.lastname: Lawrence
authors.forename: Jacek
authors.initials: J
authors.lastname: Strzelczyk
authors.forename: Neal
authors.initials: N
authors.lastname: Pawlyshyn
authors.forename: Iain D C
authors.initials: ID
authors.lastname: Kirkpatrick
mesh_terms: D000328:Adult; D000465:Algorithms; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D035002:Lower Extremity / Q000098:blood supply* / Q000473:pathology*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D010690:Phlebography / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D020246:Venous Thrombosis / Q000473:pathology*