Open AccessLabel-free assessment of hemodynamics in individual cortical brain vessels using third harmonic generation microscopy
Author(s) -
Sung Ji Ahn,
Nancy E. Ruiz-Uribe,
Baoqiang Li,
Jason Porter,
Sava Sakadžić,
Chris B. Schaffer
Publication year - 2020
Publication title -
biomedical optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.362
H-Index - 86
ISSN - 2156-7085
DOI - 10.1364/boe.385848
Subject(s) - optical coherence tomography , materials science , dextran , microscopy , biomedical engineering , femtosecond , fluorescence microscope , two photon excitation microscopy , optics , fluorescence , laser , chemistry , medicine , chromatography , physics
We show that third harmonic generation (THG) microscopy using a 1-MHz train of 1,300-nm femtosecond duration laser pulses enabled visualization of the structure and quantification of flow speed in the cortical microvascular network of mice to a depth of > 1 mm. Simultaneous three-photon imaging of an intravascular fluorescent tracer enabled us to quantify the cell free layer thickness. Using the label-free imaging capability of THG, we measured flow speed in different types of vessels with and without the presence of an intravascular tracer conjugated to a high molecular weight dextran (2 MDa FITC-dextran, 5% w/v in saline, 100 µl). We found a ∼20% decrease in flow speeds in arterioles and venules due to the dextran-conjugated FITC, which we confirmed with Doppler optical coherence tomography. Capillary flow speeds did not change, although we saw a ∼7% decrease in red blood cell flux with dextran-conjugated FITC injection.