Multiphoton Excitation Imaging of the Arterial Vascular Bed
Multiphoton excitation microscopy provides a powerful means to study the macromolecular microstructure of the arterial vascular bed. e multiphoton eect restricts excited light to the focal spot, allowing optical sectioning without the need for a confocal pinhole. is provides greatly improved photon collection eciency (compared with single-photon confocal imaging), while maintaining threedimensional submicrometric spatial resolution. Moreover, owing to the reduced tissue scattering of near-infrared excitation beams, deeper tissue penetration with minimal tissue damage can be attained. ough second-and higher-order harmonic generation (HG) is the major focus of this book, other nonlinear optical contrast mechanisms are simultaneously generated such as multiphoton excitation uorescence (MEF), and with a second excitation laser, coherent anti-Stokes Raman scattering (CARS). ese nonlinear optical microscopy techniques can be used to record three-dimensional, fully registered images of the major macromolecular elements of the arterial wall without stains or dyes. ese three readout mechanisms, together with appropriate exogenous probes, can provide a wealth of information concerning the three major elements of the diseased vascular wall, collagen (HG), elastin (MEF), and fat (CARS). ese imaging technologies provide en face imaging of wall structures relative to the blood, allowing for improved evaluation of interactions of wall structures with the vascular space, and, in specialized cases, can provide information in vivo.