title: Thrombus characterization with intravascular ultrasound: potential to predict successful thrombolysis.
abstract: OBJECTIVE
  To define analysis methods using radiofrequency (RF) data from intravascular ultrasound (IVUS) to characterize thrombus so that the success or failure of thrombolysis can be predicted.
  
  
  METHODS
  Experimentation was done in 2 phases: first, 40 clots created from platelet-rich (n=20) and platelet-poor (n=20) plasma were imaged with 20 and 30-MHz IVUS probes. The digitized RF signals were analyzed to determine the attenuation and slope of attenuation characteristics as a reference standard for the second part of the study. In this phase, 20 perfusion trials were performed with 10 platelet-rich and 10 platelet-poor samples in an in vitro arterial perfusion model; the composition of the samples was blinded during interrogation with IVUS. Alteplase (0.1 mg) was then infused directly into the thrombus for 1 hour; restoration of flow and amount of lysis were quantified.
  
  
  RESULTS
  Significant differences were detected for the integrated attenuation value (p<0.001) between platelet-poor and platelet-rich clots interrogated with a 30-MHz probe, but no differences were noted using the 20-MHz catheter. However, both transducers were capable of differentiating platelet-rich and platelet-poor clots using a slope of attenuation analysis, which was successful in identifying all 20 (100%) of the blinded clots in the in vitro model. The speed and completeness of lysis were significantly higher (p<0.05) for platelet-rich (78%) than platelet-poor (21%) clots.
  
  
  CONCLUSIONS
  IVUS preprocessed imaging is capable of differentiating various types of thrombus. This information can be used to predict the success or failure of pharmacological lysis techniques.
authors.affiliation: Department of Vascular Surgery, The Cleveland Clinic Foundation, Ohio 44195, USA.
authors.forename: Damon
authors.initials: D
authors.lastname: Kwan
authors.forename: Andrew
authors.initials: A
authors.lastname: Dries
authors.forename: Tamara
authors.initials: T
authors.lastname: Burton
authors.forename: Guru
authors.initials: G
authors.lastname: Bhandari
authors.forename: Daniel
authors.initials: D
authors.lastname: Young
authors.forename: Richard
authors.initials: R
authors.lastname: Green
authors.forename: Kenneth
authors.initials: K
authors.lastname: Ouriel
authors.forename: Roy K
authors.initials: RK
authors.lastname: Greenberg
mesh_terms: D004867:Equipment Design; D011237:Predictive Value of Tests; D015912:Thrombolytic Therapy; D013927:Thrombosis / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D014159:Transducers; D018084:Ultrasonography, Interventional