9
Advances in Blood Flow Imaging
Susan M. Daly
Department of Physics & Energy, University of Limerick, Ireland
Martin J. Leahy
Tissue Optics and Microcirculation Imaging Group, School of Physics, National University of Ire-
land, Galway, Ireland
9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
9.2 Review of Pioneering Modalities towards Dynamic Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328
9.3 Optical Sectioning Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338
9.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
9.5 Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359
This chapter describes the application of optical imaging techniques to biological tissue, to yield
both qualitative and quantitative metrics of morphological and functional information. An in-depth
narrative proffers reasoning for the diagnostic and prognostic value of such techniques via compa-
rable descriptions of its invasive predecessors. Optical sectioning techniques of both the scattering
and absorption based variety are described. The inherent need for non-invasive imaging modalities
in modern medicine is discussed, in addition to the advantageous applications of their use and cur-
rent limitations affecting performance.
Key words: biophotonics, circulation, correlation, flow, microvasculature, optical imaging, optical
sectioning
9.1 Introduction
The analysis of light interactions with biological tissue facilitates a non-invasive morphological
and functional “optical biopsy” [1], both of which are of outward importance diagnostically and
prognostically. A biopsy of this form may be juxtaposed to its core or excisional biopsy precursor,
wherein the procedure involves the surgical removal of a sampling of cells or tissues for examina-
tion via microscopy or chemical analysis. The medical removal of tissue from a living subject to
determine the presence or extent of a disease is a commonplace procedure in clinical practice.
In addition to gleaning structural data, vascular imaging makes it possible to quantify the num-
ber and spacing of blood vessels, assess blood flow and permeability [2, 3], analyse cellular and
molecular abnormalities and vessel wall shear stresses [4]. Structural and functional parameters
may be elucidated by methods ranging from fluorescence to confocal and multiphoton micros copy.
Magnetic resonance imaging, computed tomography, positron emission tomography, ultrasonogra-
phy and optical imaging have been shown to provide non-invasive, functionally relevant images of
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