title: Chronic thrombus detection with in vivo magnetic resonance imaging and a fibrin-targeted contrast agent.
abstract: BACKGROUND
  Arterial thrombosis plays a critical role in acute coronary syndromes and stroke. Therefore, the ability to detect thrombus in vivo has a significant clinical implication. Magnetic resonance imaging (MRI) has shown promise in noninvasive thrombus detection. However, thrombus characterization and age definition remain difficult. We sought to evaluate the use of a fibrin-targeted peptide (EP-2104R) for MR thrombus detection and to compare this modality with non-contrast-enhanced (NCE) MRI and with Gd-DTPA injection at various ages and time points after thrombus generation.
  
  
  RESULTS
  Carotid artery thrombosis was induced by external injury and stasis in 18 rabbits. T1-weighted MRI was performed before and after contrast agent injection, within 6 hours of thrombus induction, at 48 hours, at 1 week, and every week up to 8 weeks after injury. Correlation with histopathology was performed. The fibrin-targeted contrast agent accurately detected all thrombi, regardless of their size, location, and age. Although thrombus signal intensity after injection decreased with thrombus age (P<0.001), enhancement at 8 weeks was still present. Gd-DTPA injection was not associated with an improvement of thrombus detection. EP-2104R was superior to both NCE and Gd-DTPA injection (P<0.001). Histopathologic examination showed thrombus organization over time. Fibrin was gradually replaced by fibrous tissue. A strong correlation was found between thrombus enhancement and collagen content of the organizing thrombus with time (R=-0.89; P<0.001).
  
  
  CONCLUSIONS
  In an experimental animal model of carotid thrombosis, we have demonstrated the superiority of a fibrin-targeted MR contrast agent for in vivo detection of chronic or organized thrombus, compared with NCE MRI and Gd-DTPA injection.
authors.affiliation: Department of Cardiology, Hôpital Lariboisière, Paris, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Sirol
authors.forename: Valentin
authors.initials: V
authors.lastname: Fuster
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Badimon
authors.forename: John T
authors.initials: JT
authors.lastname: Fallon
authors.forename: Pedro R
authors.initials: PR
authors.lastname: Moreno
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Toussaint
authors.forename: Zahi A
authors.initials: ZA
authors.lastname: Fayad
mesh_terms: D000818:Animals; D002340:Carotid Artery Diseases / Q000175:diagnosis* / Q000473:pathology; D002908:Chronic Disease; D003287:Contrast Media; D005682:Gadolinium; D019786:Gadolinium DTPA; D008279:Magnetic Resonance Imaging; D010455:Peptides; D011817:Rabbits; D013927:Thrombosis / Q000175:diagnosis* / Q000473:pathology
chemical_list: D003287:Contrast Media; C503783:EP-2104R; D010455:Peptides; D005682:Gadolinium; D019786:Gadolinium DTPA