title: Noninvasive detection of intimal xanthoma using combined ultrasound, strain rate and photoacoustic imaging.
abstract: BACKGROUND
  The structure, composition and mechanics of carotid artery are good indicators of early progressive atherosclerotic lesions. The combination of three imaging modalities (ultrasound, strain rate and photoacoustic imaging) which could provide corroborative information about the named arterial properties could enhance the characterization of intimal xanthoma.
  
  
  METHODS
  The experiments were performed using a New Zealand white rabbit model of atherosclerosis. The aorta excised from an atherosclerotic rabbit was scanned ex vivo using the three imaging techniques: (1) ultrasound imaging of the longitudinal section: standard ultrasound B-mode (74Hz frame rate); (2) strain rate imaging: the artery was flushed with blood and a 1.5Hz physiologic pulsation was induced, while the ultrasound data were recorded at higher frame rate (296Hz); (3) photoacoustic imaging: the artery was irradiated with nanosecond pulsed laser light of low fluence in the 1210-1230nm wavelength range and the photoacoustic data was recorded at 10Hz frame rate. Post processing algorithms based on cross-correlation and optical absorption variation were implemented to derive strain rate and spectroscopic photoacoustic images, respectively.
  
  
  RESULTS
  Based on the spatio-temporal variation in displacement of different regions within the arterial wall, strain rate imaging reveals differences in tissue mechanical properties. Additionally, spectroscopic photoacoustic imaging can spatially resolve the optical absorption properties of arterial tissue and identify the location of lipid pools.
  
  
  CONCLUSIONS
  The study demonstrates that ultrasound, strain rate and photoacoustic imaging can be used to simultaneously evaluate the structure, the mechanics and the composition of atherosclerotic lesions to improve the assessment of plaque vulnerability.
authors.affiliation: Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Iulia M
authors.initials: IM
authors.lastname: Graf
authors.forename: Seungsoo
authors.initials: S
authors.lastname: Kim
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.forename: Richard
authors.initials: R
authors.lastname: Smalling
authors.forename: Stanislav
authors.initials: S
authors.lastname: Emelianov
mesh_terms: D000465:Algorithms; D000818:Animals; D001011:Aorta / Q000000981:diagnostic imaging / Q000473:pathology; D050197:Atherosclerosis / Q000000981:diagnostic imaging* / Q000473:pathology; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000473:pathology; D003952:Diagnostic Imaging; D061088:Photoacoustic Techniques; D011817:Rabbits; D013057:Spectrum Analysis; D017539:Tunica Intima / Q000000981:diagnostic imaging / Q000473:pathology; D014463:Ultrasonography; D014652:Vascular Diseases / Q000000981:diagnostic imaging / Q000473:pathology; D014973:Xanthomatosis / Q000000981:diagnostic imaging / Q000473:pathology*