title: Molecular MR imaging of human thrombi in a swine model of pulmonary embolism using a fibrin-specific contrast agent.
abstract: OBJECTIVE
  Molecular targeted MR imaging of human clots material in a model of pulmonary embolism using a fibrin-specific magnetic resonance imaging contrast agent (EP-2104R, EPIX Pharmaceuticals, Cambridge, MA).
  
  
  METHODS
  Fresh ex vivo engineered thrombi (human blood) and human clots removed from patients were delivered in 11 swine. Molecular MR imaging with a 3D gradient-echo [3D fast field echo (3DFFE)] sequence and a navigator-gated and cardiac-triggered 3D inversion-recovery black-blood gradient-echo sequence (IR) was performed before thrombus delivery, after thrombus delivery but before contrast media application, and 2 hours after i.v. administration of 4 micromol/kg EP-2104R. MR images were analyzed by 2 investigators and contrast-to-noise ratio (CNR) was assessed. Thrombi were removed for assessment of gadolinium (Gd) concentration.
  
  
  RESULTS
  Only after contrast media application were pulmonary emboli [freshly engineered thrombi (n = 23) and human clot material removed from patients (n = 25)] visualized as white foci on MR images. CNR was 13 +/- 3 (ex vivo engineered clot) and 22 +/- 9 (patient clot material) for the fast field echo (FFE)-sequence and 29 +/- 9 (ex vivo engineered clot) and 43 +/- 18 (patient clot material) for the IR-sequence, respectively. A high Gd concentration in the clots was found (82 +/- 43 microM for the freshly engineered and 247 +/- 44 microM for the clots removed from patients, respectively).
  
  
  CONCLUSIONS
  EP-2104R allows for molecular MR imaging of human clot material in the pulmonary vessels of a swine model.
authors.affiliation: Departments of Diagnostic Radiology, Aachen Technical University, Aachen, Germany. spuenti@rad.rwth-aachen.de
authors.forename: Elmar
authors.initials: E
authors.lastname: Spuentrup
authors.forename: Marcus
authors.initials: M
authors.lastname: Katoh
authors.forename: Arno
authors.initials: A
authors.lastname: Buecker
authors.forename: Bernd
authors.initials: B
authors.lastname: Fausten
authors.forename: Andrea J
authors.initials: AJ
authors.lastname: Wiethoff
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Wildberger
authors.forename: Patrick
authors.initials: P
authors.lastname: Haage
authors.forename: Edward C
authors.initials: EC
authors.lastname: Parsons
authors.forename: Rene M
authors.initials: RM
authors.lastname: Botnar
authors.forename: Philip B
authors.initials: PB
authors.lastname: Graham
authors.forename: Manfred
authors.initials: M
authors.lastname: Vettelschoss
authors.forename: Rolf W
authors.initials: RW
authors.lastname: Günther
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000737:chemistry*; D004195:Disease Models, Animal; D005337:Fibrin / Q000737:chemistry* / Q000378:metabolism; D005682:Gadolinium / Q000737:chemistry*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000378:metabolism; D013552:Swine
chemical_list: D003287:Contrast Media; C503783:EP-2104R; D010455:Peptides; D005337:Fibrin; D005682:Gadolinium