title: 99mTc-annexin-V functional imaging of luminal thrombus activity in abdominal aortic aneurysms.
abstract: BACKGROUND
  The mural thrombus of abdominal aortic aneurysms (AAA) is involved in aneurysm progression via several interdependent biological processes including platelet activation. 99mTc-annexin V (ANX) is a scintigraphic tracer that binds to phosphatidylserine exposed on activated platelets and apoptotic cells. Here, we evaluated the potential of ANX imaging to assess mural thrombus biological activity in an experimental AAA model. The clinical applicability was further tested ex vivo on human samples of excised AAA thrombi.
  
  
  RESULTS
  Experimental AAA was created by infusing elastase into infrarenal abdominal aorta in 17 rats, and 6 sham-operated rats were used as controls. Abdominal ANX scintigraphy was performed 2 weeks later followed by quantitative autoradiography and histological studies. Among the 13 rats which developed AAA, 11 displayed intense ANX uptake within AAA by scintigraphy. ANX uptake in the aneurysms on planar and single-photon emission computed tomography (SPECT) imaging was higher than that observed in infrarenal aorta of sham-operated controls (target/background ratio: 5.7+/-0.9 versus 1.33+/-0.21; P<0.005 for SPECT). Aneurysm-to-background activity ratios obtained by scintigraphy correlated with ANX activity in corresponding autoradiograms (R=0.69; P<0.02). This activity was located in the thrombus area where activated platelets and polymorphonuclear leukocytes accumulated. Similar patterns were also found in all of the 7 human AAA thrombi harvested during surgery.
  
  
  CONCLUSIONS
  ANX imaging may assess mural thrombus renewal activity linked to permanent flowing blood interface.
authors.affiliation: Service de Médecine Nucléaire, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France. sarda@bichat.inserm.fr
authors.forename: Laure
authors.initials: L
authors.lastname: Sarda-Mantel
authors.forename: Michèle
authors.initials: M
authors.lastname: Coutard
authors.forename: François
authors.initials: F
authors.lastname: Rouzet
authors.forename: Olivier
authors.initials: O
authors.lastname: Raguin
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Vrigneaud
authors.forename: Florence
authors.initials: F
authors.lastname: Hervatin
authors.forename: Geneviève
authors.initials: G
authors.lastname: Martet
authors.forename: Ziad
authors.initials: Z
authors.lastname: Touat
authors.forename: Pascal
authors.initials: P
authors.lastname: Merlet
authors.forename: Dominique
authors.initials: D
authors.lastname: Le Guludec
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Michel
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000493:pharmacokinetics; D017544:Aortic Aneurysm, Abdominal / Q000150:complications*; D001345:Autoradiography; D006801:Humans; D007158:Immunologic Techniques; D008297:Male; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics; D051381:Rats; D011917:Rats, Inbred Lew; D013927:Thrombosis / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D017304:Annexin A5; D015609:Organotechnetium Compounds; C417036:technetium Tc 99m annexin V