title: MR imaging of pulmonary embolism: diagnostic accuracy of contrast-enhanced 3D MR pulmonary angiography, contrast-enhanced low-flip angle 3D GRE, and nonenhanced free-induction FISP sequences.
abstract: OBJECTIVE
  To evaluate relative detection of pulmonary embolism (PE) with standard bolus-triggered contrast-enhanced breath-hold magnetic resonance (MR) pulmonary angiography, contrast-enhanced recirculation-phase breath-hold low-flip angle three-dimensional (3D) gradient-echo (GRE), and nonenhanced free-induction cardiac- and respiratory-triggered true fast imaging with steady-state precession (FISP) MR sequences.
  
  
  METHODS
  The study was HIPAA compliant and institutional review board approved. Twenty-two patients with a computed tomographic (CT) angiography diagnosis of PE underwent MR imaging within 48 hours of CT. MR included three complementary techniques: MR pulmonary angiography, 3D GRE, and triggered true FISP. Each sequence was analyzed separately by two independent reviewers who recorded presence of emboli in categorized pulmonary artery anatomic territories. CT angiography results were analyzed by a third independent reviewer, who retrospectively recorded presence of emboli using the same format; these results served as the reference standard. Sensitivity, specificity, and positive and negative predictive values for PE detection were calculated for each MR technique on a per-embolus basis, and 95% confidence intervals were calculated according to the efficient-score method. A two-sample t test was used to compare values among MR techniques.
  
  
  RESULTS
  Sensitivities for PE detection were 55% for MR pulmonary angiography, 67% for triggered true FISP, and 73% for 3D GRE MR imaging. Combining all three MR sequences improved overall sensitivity to 84%. Specificity was 100% for all detection methods except for MR pulmonary angiography (one false-positive). Agreement between readers was high (κ = 0.87). Embolus detection rates were lowest in the lingula branch for all MR sequences compared with remainder of the vascular territories (P = .07).
  
  
  CONCLUSIONS
  There are complementary benefits to combining standard MR pulmonary angiography, 3D GRE, and triggered true FISP MR examinations for evaluation of PE.
authors.affiliation: Department of Radiology, Emory University School of Medicine, Atlanta, GA, USA.
authors.forename: Bobby
authors.initials: B
authors.lastname: Kalb
authors.forename: Puneet
authors.initials: P
authors.lastname: Sharma
authors.forename: Stefan
authors.initials: S
authors.lastname: Tigges
authors.forename: Gaye L
authors.initials: GL
authors.lastname: Ray
authors.forename: Hiroumi D
authors.initials: HD
authors.lastname: Kitajima
authors.forename: James R
authors.initials: JR
authors.lastname: Costello
authors.forename: Zhengjia
authors.initials: Z
authors.lastname: Chen
authors.forename: Diego R
authors.initials: DR
authors.lastname: Martin
mesh_terms: D000368:Aged; D000792:Angiography / Q000379:methods*; D055424:Cardiac-Gated Imaging Techniques; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011655:Pulmonary Embolism / Q000175:diagnosis*; D055425:Respiratory-Gated Imaging Techniques; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media