title: MDCT evaluation of pulmonary embolism in children and young adults following a lateral tunnel Fontan procedure: optimizing contrast-enhancement techniques.
abstract: BACKGROUND
  Pulmonary embolism (PE) is a life-threatening thromboembolic complication in patients who have undergone a Fontan procedure for augmenting pulmonary blood flow in the setting of single-ventricle physiology. In patients following a Fontan procedure, lack of proper contrast agent mixing in the right atrium and sluggish, low-velocity blood flow within the Fontan circulation often results in suboptimal contrast enhancement within the pulmonary artery for evaluating PE. Unfortunately, there is a paucity of information describing the optimal contrast-enhancement technique with multidetector CT (MDCT) for evaluating PE in children and young adults following a Fontan procedure.
  
  
  OBJECTIVE
  We illustrate the MDCT imaging findings of suboptimal contrast enhancement within the pulmonary artery, which can be mistaken for PE, in patients following a lateral Fontan procedure, and we discuss MDCT techniques to optimize contrast enhancement within the pulmonary artery in these patients for evaluating PE.
  
  
  METHODS
  The MDCT imaging findings in pediatric and young adult patients following a lateral Fontan procedure and with clinically suspected PE are illustrated. We describe intravenous contrast agent injection techniques that can be used to optimize the contrast enhancement in the pulmonary artery in patients following a lateral Fontan procedure.
  
  
  RESULTS
  The use of a suboptimal contrast-enhancement technique led to initial misdiagnosis and incomplete evaluation of PE in the three patients following a lateral Fontan procedure. Imaging in two patients showed that optimal evaluation of thrombosis in the Fontan pathway and PE in the pulmonary arteries can be successfully achieved with simultaneous upper- and lower-limb injections of contrast agent.
  
  
  CONCLUSIONS
  This series demonstrates that suboptimal contrast enhancement can result in misdiagnosis or incomplete evaluation of PE in children and young adults following a lateral Fontan procedure. Careful attention to optimizing contrast enhancement during MDCT examination for evaluation of PE in these patients is essential to prevent misdiagnosis and incomplete evaluation.
authors.affiliation: Department of Radiology, Children's Hospital Boston and Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Sanjay P
authors.initials: SP
authors.lastname: Prabhu
authors.forename: Soran
authors.initials: S
authors.lastname: Mahmood
authors.forename: Laureen
authors.initials: L
authors.lastname: Sena
authors.forename: Edward Y
authors.initials: EY
authors.lastname: Lee
mesh_terms: D000328:Adult; D000792:Angiography / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D005260:Female; D018729:Fontan Procedure / Q000009:adverse effects*; D006801:Humans; D008297:Male; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging* / Q000209:etiology*; D011856:Radiographic Image Enhancement / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
chemical_list: D003287:Contrast Media