title: Magnetic resonance pulmonary angiography and direct imaging of embolus for the detection of pulmonary emboli.
abstract: OBJECTIVE
  The authors developed a two-dimensional breathhold magnetic resonance (MR) technique for the direct imaging of pulmonary emboli.
  
  
  METHODS
  In vitro MR imaging was performed to demonstrate the potential generation of clot-blood contrast by in vivo pulmonary embolism (PE). A two-dimensional magnetization prepared gradient-echo (turbo-FLASH) breathhold technique was designed to directly image intravascular emboli by the selective nulling of the blood signal. A turbo-FLASH pulmonary angiographic breathhold sequence was used to provide spatial localization of detected emboli. Thirteen patients with suspected PE were studied; 6 patients underwent conventional pulmonary angiography (CPA) and the remaining 7 had diagnoses based on findings from other studies.
  
  
  RESULTS
  In vitro study of blood clot demonstrated an initial rise and then fall in T1 sufficient to generate clot-blood contrast after eight days of clot formation. All patients with CPA or alternative study evidence of PE were diagnosed as positive with direct embolus imaging MR. There were no false-positive diagnoses. Three additional emboli were detected using the MR technique compared with CPA. The MR pulmonary angiographic sequence provided a useful road map for localization of intravascular emboli but was less sensitive for PE detection than the embolus imaging technique.
  
  
  CONCLUSIONS
  The direct imaging of PE is feasible using a simple two-dimensional breathhold technique.
authors.affiliation: Department of Human Morphology, University Hospital, Queen's Medical Centre, Nottingham, United Kingdom.
authors.forename: A R
authors.initials: AR
authors.lastname: Moody
authors.forename: A
authors.initials: A
authors.lastname: Liddicoat
authors.forename: K
authors.initials: K
authors.lastname: Krarup
mesh_terms: D000328:Adult; D000368:Aged; D000792:Angiography; D005189:False Positive Reactions; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000473:pathology*; D011655:Pulmonary Embolism / Q000175:diagnosis*; D012680:Sensitivity and Specificity