title: Imaging and quantitative analysis of atherosclerotic lesions by CARS-based multimodal nonlinear optical microscopy.
abstract: OBJECTIVE
  The purpose of this study was to assess the ability of label-free multimodal nonlinear optical (NLO) microscopy to characterize, and thus enable quantitative in situ analyses of, different atherosclerotic lesion types, according to the original scheme suggested by the AHA Committee.
  
  
  RESULTS
  Iliac arteries were taken from 24 male Ossabaw pigs divided into lean control and metabolic syndrome groups and were imaged by multimodal NLO microscopy where sum-frequency generation (SFG) and 2-photon excitation fluorescence (TPEF) were integrated on a coherent anti-Stokes Raman scattering (CARS) microscope platform. Foam cells, lipid deposits, matrices, and fibrous caps were visualized with submicron 3D resolution. Starting from the adaptive intimal thickening in the initial stage to the fibrous atheroma or mineralization in the advanced stages, lesions were visualized without labels. Histological staining of each lesion confirmed the lesion stages. Lipid and collagen contents were quantitatively analyzed based on the CARS and SFG signals. Lipid accumulation in thickened intima culminated in type IV whereas the highest collagen deposition was found in Type V lesions. Luminal CARS imaging showed the capability of viewing the location of superficial foam cells that indicate relatively active locus in a lesion artery.
  
  
  CONCLUSIONS
  We have demonstrated the capability of CARS-based multimodal NLO microscopy to interrogate different stages of lesion development with subcellular detail to permit quantitative analysis of lipid and collagen contents.
authors.affiliation: Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Ind., USA.
authors.forename: Han-Wei
authors.initials: HW
authors.lastname: Wang
authors.forename: Ingeborg M
authors.initials: IM
authors.lastname: Langohr
authors.forename: Michael
authors.initials: M
authors.lastname: Sturek
authors.forename: Ji-Xin
authors.initials: JX
authors.lastname: Cheng
mesh_terms: D000818:Animals; D050197:Atherosclerosis / Q000378:metabolism / Q000473:pathology*; D003094:Collagen / Q000032:analysis; D004195:Disease Models, Animal; D018450:Disease Progression; D005355:Fibrosis; D005487:Foam Cells / Q000473:pathology; D007083:Iliac Artery / Q000737:chemistry / Q000473:pathology*; D021621:Imaging, Three-Dimensional; D008055:Lipids / Q000032:analysis; D008297:Male; D024821:Metabolic Syndrome / Q000378:metabolism / Q000473:pathology*; D036641:Microscopy, Fluorescence, Multiphoton; D017711:Nonlinear Dynamics; D013059:Spectrum Analysis, Raman; D013552:Swine; D013556:Swine, Miniature
chemical_list: D008055:Lipids; D003094:Collagen